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Article

A Cascade Synthesis of Unsymmetrical Furanized Triarylmethanes via Gold Self-Relay Catalysis

by
Qian Rao
†,
Yan Zhang
†,
Xin-Yu Gu
†,
Yin-Ping Liu
,
Bo Jiang
* and
Wen-Juan Hao
*
School of Chemistry and Materials Science, Jiangsu Key Laboratory of Green Synthetic Chemistry for Functional Materials, Jiangsu Normal University, Xuzhou 221116, China
*
Authors to whom correspondence should be addressed.
†
These authors contributed equally to this work.
Catalysts 2023, 13(7), 1051; https://doi.org/10.3390/catal13071051
Submission received: 12 June 2023 / Revised: 27 June 2023 / Accepted: 28 June 2023 / Published: 29 June 2023
(This article belongs to the Special Issue Catalytic Annulation Reactions)
Browse Figures
Versions Notes

Abstract

:
In this paper, A new gold self-relay catalysis enabling intramolecular annulation and intermolecular Michael addition of 3-yne-1,2-diols with aurone-derived azadienes (or para-quinone methides) is reported, efficiently furnishing a range of unsymmetrical furanized triarylmethanes with substituent diversity in good yields. The overall process was governed by the π- and σ-Lewis acid capability of gold complexes, providing a catalytic strategy for constructing triarylmethane skeletons.

1. Introduction

Scaffolds with triaryl-substituted carbon, especially with a carbon atom linked to three different aryl rings, are frequently encountered in numerous functional materials, pharmaceutical agents, and biologically active molecules [1,2,3,4]. These appealing contributions advance the development of reliable and versatile synthetic strategies for the assembly of unsymmetrical triarylmethanes (TAMs). Traditionally, unsymmetrical triarylmethane synthesis is heavily dependent on Lewis-acid- or Brønsted-acid-catalyzed Friedel–Crafts reactions between nucleophilic electron-rich arenes and unsymmetrical diarylmethanols or related derivatives (Scheme 1a) [5,6,7,8,9,10]. The following catalytic strategies include transition-metal-catalyzed cross-coupling reactions [11,12,13,14,15,16] and C–H functionalization (Scheme 1b) [17,18,19,20], employing Pd [21,22,23], Cu [24,25], Ni [26,27,28,29], Fe [30], and Rh [31,32]. Recently, the organo- or metal-catalyzed 1,6-conjugate addition of p-quinone methides (p-QMs) with aryl electrophiles has emerged as an alternative method to synthesize these skeletons (Scheme 1c) [33,34,35,36,37]. Moreover, the catalytic 1,4-conjugate addition of o-quinone methides (o-QMs) with electronically rich arenes provides efficient access to unsymmetrical triarylmethanes (Scheme 1d) [38]. Despite great advances in this field, only limited examples are available for the synthesis of unsymmetrical TAMs with furan groups [23,25] because of the high sensitivity of furans to acids, bases, and partial metal salts. Therefore, developing a new and broadly applicable method using readily available starting materials and an environmentally benign catalyst for the generation of unsymmetrical furanized triarylmethanes is in great demand.
Homogeneous gold catalysis has attracted long-standing attention from organic chemists over the past two decades [39,40,41,42]. This is attributed to the fact that such catalysis can produce numerous natural products and bioactive functional molecules and provide great potential for drug discovery and biomedical research. Notably, the salient features of such catalysis include mild conditions, high efficiency and excellent selectivity, and even gold catalysts have lower toxicity and higher environmental compatibility than other transition metals [43,44,45,46,47]. Specifically, gold self-relay catalysis, which catalyzes two or more distinct elementary reactions under the same reaction conditions, extensively enhances synthetic efficiency and has attracted great interest in the organic community [48,49,50,51]. Many elegant gold self-relay catalysis reactions for the construction of complex cyclic structures have been documented [52,53,54]. A particularly attractive gold-catalyzed cyclodehydration of 3-yne-1,2-diols toward functionalized furans was recently demonstrated, showing the compatibility between gold catalysts and furans [55,56,57]. Along this line, we reasoned that the utilization of furans generated in situ from 3-yne-1,2-diols as soft pronucleophiles to react with suitable 1,4-Michael acceptors under the catalysis of gold catalysts may generate unsymmetrical furanized triarylmethanes. In an attempt to add to the literature on relay catalysis [58,59,60], in this paper, we describe the gold relay catalysis of 3-yne-1,2-diols 1 and aurone-derived azadienes 2, allowing catalytic annulation and subsequent 1,4-addition to give furanized triarylmethanes 3 in good yields (Scheme 1e). Exchanging aurone-derived azadienes for para-quinone methides (p-QMs) 4 resulted in skeletally different furanized triarylmethanes 5 with good yields through a cascade annulation and subsequent 1,6-addition sequence (Scheme 1d). It is worth noting that the present protocol demonstrates the simultaneous utilization of two robust π- and σ-acidity of gold catalysts, enabling their catalytic activation modes to sequentially govern a complex process consisting of annulation and nucleophilic addition.

2. Results

Initially, a model reaction of 3-yne-1,2-diol 1a with aurone-derived azadiene 2a in 1,2-dichloroethane (DCE) in the presence of 2.0 mol% JohnPhosAu(MeCN)SbF6 was investigated at room temperature under air conditions. To our delight, the targeted triarylmethane product 3a was obtained in 85% yield (Table 1, entry 1). Then, several other transition metal catalysts frequently encountered in catalytic transformations, such as IPrAuNTf2, AuCl3, AgNO3, PbCl2, and CuCl2, were tested (entries 2–6). The results revealed that the former one could drive the conversion of 1a with 2a into 3a but demonstrated lower catalytic capability and thus gave a lower yield compared with JohnPhosAu(MeCN)SbF6 (entry 2 vs. entry 1); in contrast, the latter four completely suppressed the generation of 3a (entries 3–6). The next step of our investigation was the determination of the solvent effect in the process, and several aprotic solvents, such as tetrahydrofuran (THF), acetonitrile, toluene, 1,4-dioxane, and dichloromethane (DCM), were examined (entries 7–11). After careful screening, it was found that the use of the former three solvents remained almost ineffective, as only a trace amount of product 3a was detected (entries 7–9); whereas the latter two could drive the transformation but decreased the efficiency compared to DCE (entries 10–11 vs. entry 1). Without a gold catalyst, the reaction could not proceed, and the starting materials were not consumed (entry 12), suggesting that the gold catalyst is crucial for this transformation.
With the optimized conditions established, a set of 3-yne-1,2-diols 1 and aurone-derived azadienes 2 were exploited to systematically investigate the generalization of this gold self-relay catalysis. As described in Scheme 2, the influence of substituents in the aromatic ring directly bound to the alkyne unit of 3-yne-1,2-diols, including their electronic and steric effects, was initially examined in combination with 2a and 1. A variety of functional groups, such as methyl (1b–1c), methoxy (1d), chloro (1e–1g), and bromo (1h), located at different positions (para, meta, or ortho) of the phenyl ring were probed to prove the tolerance of this protocol, and all these groups did not hamper the reaction process, furnishing products 3b–3h in 80–87% yields. Of these substituents, the counterparts of o-tolyl (1b) and o-chlorophenyl (1e) with strong steric congestion are highly reactive, demonstrating that the increase in steric hindrance had a negligible influence on the reactivity. As exemplified by substrates 1i and 1j, this gold self-relay catalysis is also adaptable to the alkynyl moiety linked by alkyl groups such as tert-butyl (3i, 78%) and n-pentyl (3j, 75%) in synthetically useful yields. Interestingly, the transformation of substrate 1k with a terminal alkyne enabled regioselective entry to access product 3k in 70% yield. Next, a brief survey of the possible variation in the arene ring (Ar) of substrates 2 was conducted by repeating the reaction with substrate 1k bearing two phenyl groups. The reaction was efficient in the presence of electronically neutral (H, 2a), rich (ortho-methyl 2b, meta-methyl 2c), and para-methl 2d) and poor (para-chloro 2e, 2,6-dichloro 2f, ortho-bromo 2g, meta-bromo 2h, and para-bromo 2i) groups located in the phenyl ring of 2, and the corresponding products 3l–3t were offered with comparable efficiency. In addition, arylsulfonyl groups tethered by imine functionality in substrates 2 were also examined. The results showed that both the tert-butyl and bromo groups at the para-position in the phenyl ring relative to the sulfonyl groups were compatible, providing products 3u–3v in good yields.
Next, the scope of this gold self-relay catalysis was carefully investigated by employing a variety of para-quinone methides (p-QMs) 4 as 1,6-addition acceptors (Scheme 3) [36,37]. The reaction worked well under the standard conditions, giving access to a series of substituent-diverse furanized triarylmethanes 5a–5l in good yields. As expected, electronically neutral (e.g., H, 4a), rich (e.g., methyl 4b–4d and methoxy 4e–4f), and poor (e.g., fluoro 4g and chloro 4h–4i) substituents at the phenyl ring of p-QMs were all compatible. Among them, the sterically crowded o-tolyl substrate 4b was also amenable, delivering product 5b in 81% yield. Exchanging the phenyl ring linked by the alkyne unit for a para-methoxyphenyl group led to the generation of product 5j in 75% yield. Similarly, swapping the methyl group anchored by a quaternary carbon center of 1 to an ethyl substituent proved to be applicable, as product 5k was obtained in 85% yield. Furthermore, the reaction proceeded smoothly with the tolerance of two phenyl groups on the 3-yne-1,2-diol motif (5l). The structures of these resulting unsymmetrical triarylmethanes were fully determined via NMR spectroscopy and HRMS data (see the Supporting Information). Furthermore, the structure of 3k was identified via X-ray diffraction analysis (Figure 1, CCDC 2269111).
To gain mechanistic insight into this gold catalysis, several control experiments were performed as described in Scheme 4. To ascertain the role of the gold catalyst in the 1,4-addition process, the preformed furan 6 was reacted with 2a, leading to an 84% yield of product 3a (Scheme 4a). These outcomes revealed that furans should be the great possibility of reaction intermediates. Without a gold catalyst, the reaction of furan 6 with 2a did not take place (Scheme 4b), demonstrating that the gold catalyst is crucial for every elementary reaction step; thus, a new gold self-relay catalysis involving cyclization and 1,4-addition was established.
Based on the above experimental results and the literature precedents [52,54,55], a plausible explanation of the reaction outcome is depicted in Scheme 5. With 3-yne-1,2-diol 1a and aurone-derived azadiene 2a as representative examples, this might initially involve Au(I)-catalyzed cyclodehydration and subsequent proto-deauration, yielding furan intermediate 6. Next, the coordination of the gold complex to aurone-derived azadiene 2a provides Au(I) σ-complex D, intercepted by furan 6 to give E through 1,4-addition. The following proton transfer and proto-deauration afford the expected product 3a, together with the regeneration of the gold catalyst for the next catalytic cycle. Therefore, the formation of 3a includes a tandem reaction catalyzed by the same gold complex (self-relay catalysis). In the overall process, the gold catalyst played the dual role of π-Lewis acid-type activation of the triple bond for cyclization and σ-Lewis acid-type activation of imines for Michael addition. This case represents a new example of gold-catalyzed self-relay catalysis.

3. Experimental Section

General Information. All solvents were dried over molecular sieves. Unless otherwise noted, materials obtained from commercial suppliers were used without further purification. We synthesized 3-Yne-1,2-diols according to methods outlined elsewhere [61,62,63]. Aurone-derived azadienes [64] and para-quinone methides [65] were independently prepared according to the corresponding references. The products were isolated using column chromatography on silica gel (200–300 mesh) by using petroleum ether (PE, 30–60 °C) and ethyl acetate (EA) as eluents. All yields described herein were the isolated yields after column chromatography. Reaction progress and product mixtures were routinely monitored by using TLC using TLC SiO2 sheets, and compounds were visualized under ultraviolet light. 1H NMR and 13C NMR spectra were recorded on Bruker DPX 400 MHz spectrometer. The spectra were recorded using CDCl3 as a solvent. 1H NMR chemical shifts are referenced to tetramethylsilane (TMS, 0 ppm). Abbreviations are as follows: s (singlet), d (doublet), t (triplet), q (quartet), m (multiplet). High-resolution mass spectra (HRMS) were recorded on a microTOF-QII HRMS/MS instrument (BRUKER). X-ray crystallographic analysis was performed using a Siemens SMART CCD and a Siemens P4 diffractometer.
General procedure for the synthesis of products 3a–3v
The following were successively added to a 10-mL pressure tube under air conditions: 2-methyl-4-phenylbut-3-yne-1,2-diol (1a, 0.2 mmol, 2.0 equiv, 31.2 mg), aurone-derived azadiene (2a, 0.2 mmol, 1.0 equiv, 75.0 mg), JohnPhosAu(MeCN)SbF6 (2.0 mol%, 1.54 mg), 1,2-dichloroethane (2.0 mL). The mixture was stirred at room temperature for about 8 h. After the reaction was completed (indicated by TLC, petroleum ether:ethyl acetate = 15:1), the reaction mixture was concentrated via vacuum distillation and purified via flash column chromatography to afford the desired pure product (3a, 90.1 mg, 85% yield) as a white solid.

3.1. 4-Methyl-N-(2-((3-methyl-5-phenylfuran-2-yl)(phenyl)methyl)benzofuran-3-yl)benzenesulfonamide (3a)

White solid (90.1 mg, 85% yield); m.p.: 134–136 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.62 (d, J = 8.0 Hz, 2H), 7.57 (d, J = 8.0 Hz, 2H), 7.41 (d, J = 8.0 Hz, 1H), 7.36–7.32 (m, 2H), 7.29 (s, 2H), 7.25–7.23 (m, 5H), 7.12–7.08 (m, 4H), 6.48 (s, 1H), 6.27 (s, 1H), 5.71 (s, 1H), 2.32 (s, 3H), 1.93 (s, 3H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 153.7, 153.4, 152.3, 146.8, 144.1, 138.2, 136.3, 130.8, 129.8, 128.7, 128.6, 128.5, 127.6, 127.2, 125.7, 124.6, 123.6, 123.2, 119.2, 119.0, 113.7, 111.8, 109.0, 40.3, 21.6, 10.2; IR (KBr, ν, cm−1): 3243, 2980, 1698, 1601, 1495, 1445, 760, 692; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C33H26NO4S 532.1583; Found 532.1592.

3.2. 4-Methyl-N-(2-((3-methyl-5-(o-tolyl)furan-2-yl)(phenyl)methyl)benzofuran-3-yl)benzenesulfonamide (3b)

White solid (92.1 mg, 84% yield); m.p.: 151–152 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.62 (d, J = 8.4 Hz, 2H), 7.59 (d, J = 7.2 Hz, 1H), 7.39 (d, J = 8.0 Hz, 1H), 7.30 (d, J = 6.8 Hz, 1H), 7.24 (d, J = 8.0 Hz, 3H), 7.21–7.17 (m, 4H), 7.12–7.08 (m, 4H), 6.39 (s, 1H), 6.27 (s, 1H), 5.73 (s, 1H), 2.42 (s, 3H), 2.33 (s, 3H), 1.98 (s, 3H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 153.7, 153.4, 152.3, 146.4, 144.1, 138.3, 136.3, 134.5, 131.3, 130.1, 129.8, 128.6, 128.5, 127.6, 127.3, 127.2, 126.8, 126.0, 125.7, 124.6, 123.1, 119.2, 118.4, 113.6, 112.3, 111.7, 40.3, 22.0, 21.6, 10.2; IR (KBr, ν, cm−1): 3242, 2910, 1704, 1558, 1500, 1455, 749, 674; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C34H28NO4S 546.1739; Found 546.1745.

3.3. 4-Methyl-N-(2-((3-methyl-5-(p-tolyl)furan-2-yl)(phenyl)methyl)benzofuran-3-yl)benzenesulfonamide (3c)

White solid (95.4 mg, 87% yield); m.p.: 156–156 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.62 (d, J = 8.0 Hz, 2H), 7.47 (d, J = 8.0 Hz, 2H), 7.40 (d, J = 8.0 Hz, 1H), 7.29 (d, J = 6.4 Hz, 2H), 7.25–7.20 (m, 5H), 7.15 (d, J = 7.6 Hz, 3H), 7.12–7.07 (m, 3H), 6.42 (s, 1H), 6.30 (s, 1H), 5.69 (s, 1H), 2.34 (s, 3H), 2.32 (s, 3H), 1.92 (s, 3H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 153.6, 153.4, 152.5, 146.3, 144.1, 138.3, 137.0, 136.4, 129.7, 129.4, 128.6, 128.5, 128.2, 127.6, 127.2, 125.7, 124.6, 123.6, 123.1, 119.3, 118.9, 113.7, 111.8, 108.2, 40.4, 21.6, 21.4, 10.2; IR (KBr, ν, cm−1): 3245, 2921, 1698, 1600, 1490, 1455, 784, 690; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C34H28NO4S 546.1739; Found 419.1743.

3.4. N-(2-((5-(4-Methoxyphenyl)-3-methylfuran-2-yl)(phenyl)methyl)benzofuran-3-yl)-4-methylbenzenesulfonamide (3d)

White solid (90.2 mg, 80% yield); m.p.: 145–147 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.77 (d, J = 8.0 Hz, 1H), 7.67 (d, J = 8.0 Hz, 2H), 7.46–7.44 (m, 2H), 7.36–7.33 (m, 3H), 7.30–7.27 (m, 4H), 7.20 (d, J = 8.0 Hz, 1H), 7.21–7.13 (m, 4H), 7.02 (s, 1H), 6.42 (s, 1H), 5.78 (s, 1H), 2.37 (s, 3H), 2.00 (s, 3H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 159.0, 153.6, 153.4, 152.4, 146.0, 144.1, 138.4, 136.4, 129.7, 128.6, 128.5, 128.4, 127.6, 127.2, 125.7, 125.1, 124.6, 124.0, 123.1, 119.3, 118.9, 114.2, 113.7, 107.4, 55.0, 40.4, 21.6, 10.2; IR (KBr, ν, cm−1): 3225, 2965, 1602, 1597, 1495, 1420, 782, 691;HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C34H28NO5S 562.1688; Found 562.1694.

3.5. N-(2-((5-(2-Chlorophenyl)-3-methylfuran-2-yl)(phenyl)methyl)benzofuran-3-yl)-4-methylbenzenesulfonamide (3e)

White solid (91.1 mg, 80% yield); m.p.: 188–190 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.62 (d, J = 7.6 Hz, 2H), 7.50 (d, J = 8.8 Hz, 2H), 7.40 (d, J = 8.4 Hz, 1H), 7.29 (d, J = 6.4 Hz, 2H), 7.24–7.20 (m, 4H), 7.16 (d, J = 7.6 Hz, 1H), 7.12–7.07(m, 3H), 6.88 (d, J = 8.4 Hz, 2H), 6.34 (s, 2H), 5.68 (s, 1H), 3.81 (s, 3H), 2.32 (s, 3H), 1.91 (s, 3H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 153.6, 153.4, 148.5, 147.0, 144.2, 138.1, 136.3, 130.7, 129.8, 129.7, 129.1, 128.6, 128.5, 127.8, 127.7, 127.6, 127.3, 126.9, 125.7, 124.7, 123.2, 119.2, 119.0, 115.0, 113.7, 111.8, 40.2, 21.6, 10.2; IR (KBr, ν, cm−1): 3260, 2910, 1703, 1594, 1490, 1404, 769, 692; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C33H25ClNO4S 566.1193; Found 566.1199.

3.6. N-(2-((5-(3-Chlorophenyl)-3-methylfuran-2-yl)(phenyl)methyl)benzofuran-3-yl)-4-methylbenzenesulfonamide (3f)

White solid (92.3 mg, 81% yield); m.p.: 157–158 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.63 (d, J = 8.0 Hz, 2H), 7.54 (s, 1H), 7.44–7.41 (m, 2H), 7.30–7.28 (m, 3H), 7.26–7.20 (m, 4H), 7.17 (d, J = 8.0 Hz, 1H), 7.12–7.03 (m, 4H), 6.51 (s, 1H), 6.32 (s, 1H), 5.76 (s, 1H), 2.33 (s, 3H), 1.94 (s, 3H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 153.6, 153.4, 150.8, 147.6, 144.2, 138.1, 136.4, 134.7, 132.5, 130.0, 129.8, 128.6, 128.5, 127.6, 127.3, 127.0, 125.6, 124.7, 123.6, 123.2, 121.7, 119.207, 119.1, 113.7, 111.8, 110.1, 40.3, 21.6, 10.2; IR (KBr, ν, cm−1): 3259, 2913, 1700, 1565, 1490, 1404, 743, 692; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C33H25ClNO4S 566.1193; Found 566.1197.

3.7. N-(2-((5-(4-Chlorophenyl)-3-methylfuran-2-yl)(phenyl)methyl)benzofuran-3-yl)-4-methylbenzenesulfonamide (3g)

White solid (94.5 mg, 83% yield); m.p.: 195–196 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.62 (d, J = 8.0 Hz, 2H), 7.48 (d, J = 8.0 Hz, 2H), 7.40 (d, J = 8.4 Hz, 1H), 7.30–7.28 (m, 4H), 7.25–7.29 (m, 4H), 7.11 (d, J = 8.0 Hz, 2H), 7.07 (d, J = 6.0 Hz, 2H), 6.47 (s, 1H), 6.26 (s, 1H), 5.74 (s, 1H), 2.32 (s, 3H), 1.93 (s, 3H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 153.7, 153.4, 151.2, 147.2, 144.2, 138.1, 136.4, 132.7, 129.7, 129.3, 128.9, 128.6, 128.5, 127.6, 127.3, 125.6, 124.8, 124.7, 123.2, 119.14, 119.13, 113.7, 111.8, 109.4, 40.3, 21.6, 10.2; IR (KBr, ν, cm−1): 3243, 2965, 1699, 1555, 1490, 1417, 763, 690; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C33H25ClNO4S 566.1193; Found 566.1200.

3.8. N-(2-((5-(4-Bromophenyl)-3-methylfuran-2-yl)(phenyl)methyl)benzofuran-3-yl)-4-methylbenzenesulfonamide (3h)

White solid (100.4 mg, 82% yield); m.p.: 137–138 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.63 (d, J = 8.0 Hz, 2H), 7.57 (d, J = 8.0 Hz, 2H), 7.41 (d, J = 9.6 Hz, 1H), 7.36–7.27 (m, 4H), 7.25–7.19 (m, 4H), 7.13–7.07 (m, 4H), 6.48 (s, 1H), 6.30 (s, 1H), 5.72 (s, 1H), 2.32 (s, 3H), 1.93 (s, 3H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 153.6, 153.4, 152.3, 146.8, 144.1, 138.6, 136.4, 131.8, 130.8, 129.7, 128.7, 128.6, 128.5, 127.6, 127.2, 125.7, 124.6, 123.6, 123.2, 119.2, 119.0, 113.7, 111.8, 109.0, 40.3, 21.6, 10.2; IR (KBr, ν, cm−1): 3251, 3008, 1689, 1586, 1448, 1264, 745, 693; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C33H25BrNO4S 610.0688; Found 610.0693.

3.9. N-(2-((5-(tert-Butyl)-3-methylfuran-2-yl)(phenyl)methyl)benzofuran-3-yl)-4-methylbenzenesulfonamide (3i)

White solid (80.2 mg, 78% yield); m.p.: 165–167 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.60 (d, J = 8.0, 2H), 7.36 (d, J = 8.4 Hz, 1H), 7.24 (d, J = 5.2 Hz, 4H), 7.20 (d, J = 7.6 Hz, 1H), 7.16–7.09 (m, 5H), 6.22 (s, 1H), 5.78 (s, 1H), 5.50 (s, 1H), 2.37 (s, 3H), 1.81 (s, 3H), 1.24 (s, 9H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 163.0, 153.4, 153.3, 144.4, 144.0, 138.7, 136.4, 129.7, 128.5, 128.4, 127.6, 127.0, 125.8, 124.5, 123.1, 119.6, 117.0, 113.6, 111.6, 105.9, 40.4, 32.6, 29.0, 21.7, 10.1; IR (KBr, ν, cm−1): 3223, 2912, 1688, 1597, 1490, 1448,760, 692; IR (KBr, ν, cm−1): 3266, 2909, 1669, 1603, 1496, 1354, 747, 690; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C31H30NO4S 512.1896; Found 512.1899.

3.10. 4-Methyl-N-(2-((3-methyl-5-pentylfuran-2-yl)(phenyl)methyl)benzofuran-3-yl)benzenesulfonamide (3j)

White solid (79.2mg, 75% yield); m.p.: 116–118 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.61 (d, J = 8.4 Hz, 2H), 7.38 (d, J = 8.0 Hz, 1H), 7.28 (s, 1H), 7.26–7.22 (m, 4H), 7.15–7.12 (m, 3H), 7.07 (d, J = 7.6 Hz, 2H), 6.29 (s, 1H), 5.81 (s, 1H), 5.53 (s, 1H), 2.56–2.52 (m, 2H), 2.36 (s, 3H), 1.84 (s, 3H), 1.60–1.57 (m, 2H), 1.32–1.29 (m, 4H), 0.87 (s, 3H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 155.5, 153.3, 153.3, 144.6, 144.0, 138.5, 136.3, 129.7, 128.5, 128.3, 127.6, 127.0, 125.8, 124.5, 123.1, 119.6, 117.5, 113.8, 111.7, 108.6, 40.2, 31.4, 28.0, 27.7, 22.5, 21.7, 14.1, 10.1; IR (KBr, ν, cm−1): 3235, 2965, 1668, 1602, 1495, 1448,748, 690; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C32H32NO4S 526.2052; Found 526.2059.

3.11. 4-Methyl-N-(2-(phenyl(3-phenylfuran-2-yl)methyl)benzofuran-3-yl)benzenesulfonamide (3k)

White solid (72.8 mg, 70% yield); m.p.: 133–135 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.47–7.44 (m, 5H), 7.40–7.37 (m, 3H), 7.32 (d, J = 7.6 Hz, 2H), 7.25–7.23 (m, 4H), 7.18–7.15 (m, 1H), 7.04 (d, J = 8.0 Hz, 2H), 7.00–6.98 (m, 2H), 6.53 (s, 1H), 5.86 (s, 1H), 5.62 (s, 1H), 2.29 (s, 3H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 153.5, 152.1, 147.2, 144.0, 142.4, 137.7, 136.0, 133.1, 129.7, 129.0, 128.6, 128.6 128.3, 127.6, 127.6, 127.3, 125.8, 124.8, 123.8, 123.3, 120.0, 114.3, 111.9, 111.8, 40.2, 21.6; IR (KBr, ν, cm−1): 3245, 2985, 1700, 1604, 1512, 1447, 761, 693; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C32H24NO4S 518.1426; Found 518.1435.

3.12. N-(2-((3,5-Diphenylfuran-2-yl)(phenyl)methyl)benzofuran-3-yl)-4-methylbenzenesulfonamide (3l)

White solid (112.0 mg, 94% yield); m.p.: 167–169 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.65 (d, J = 7.6 Hz, 2H), 7.50–7.40 (m, 4H), 7.42 (d, J = 11.6 Hz, 3H), 7.39–7.36 (m, 4H), 7.28 (s, 4H), 7.25 (d, J = 7.6 Hz, 1H), 7.18–7.12 (m, 3H), 7.05 (d, J = 8.0 Hz, 2H), 6.80 (s, 1H), 5.98 (s, 1H), 5.70 (s, 1H), 2.30 (s, 3H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 153.6, 153.4, 152.5, 146.8, 144.0, 137.8, 136.1, 133.1, 130.4, 129.7, 129.0, 128.8, 128.6, 128.6, 128.3, 127.7, 127.7, 127.6, 127.4, 125.8, 125.7, 124.8, 123.9, 123.3, 119.9, 114.0, 111.6, 107.1, 40.4, 21.6; IR (KBr, ν, cm−1): 3256, 2987, 1700, 1610, 1454, 1336, 866, 745; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C38H28NO4S 594.1739; Found 594.1747.

3.13. N-(2-((3,5-Diphenylfuran-2-yl)(o-tolyl)methyl)benzofuran-3-yl)-4-methylbenzenesulfonamide (3m)

White solid (90.3 mg, 74% yield); m.p.: 180–182 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.61 (d, J = 7.6 Hz, 2H), 7.49 (d, J = 7.6 Hz, 1H), 7.40–7.38 (m, 5H), 7.35 (d, J = 6.0 Hz, 3H), 7.28 (m, 4H), 7.19 (d, J = 6.4 Hz, 3H), 7.18 (s, 1H), 7.11 (d, J = 4.4 Hz, 1H), 6.93 (d, J = 7.6 Hz, 2H), 6.82 (d, J = 5.6 Hz, 1H), 6.10 (s, 1H), 5.80 (s, 1H), 2.25 (s, 3H), 1.94 (s, 3H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 153.4, 153.4, 151.3, 146.5, 143.8, 136.4, 136.3, 136.1, 136.0, 133.1, 130.7, 130.4, 129.6, 128.9, 128.8, 128.8, 128.0, 127.6, 127.4, 127.4, 126.5, 125.8, 125.5, 124.7, 123.9, 123.2, 120.2, 114.4, 111.7, 107.1, 38.8, 21.6, 19.4; IR (KBr, ν, cm−1): 3235, 2895, 1688, 1607, 1595, 1458, 762, 691; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C39H30NO4S 608.1896; Found 608.1899.

3.14. N-(2-((3,5-Diphenylfuran-2-yl)(m-tolyl)methyl)benzofuran-3-yl)-4-methylbenzenesulfonamide (3n)

White solid (100.0 mg, 82% yield); m.p.: 192–194 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.67–7.65 (m, 2H), 7.49–7.46 (m, 4H), 7.42 (d, J = 8.0 Hz, 3H), 7.39 (s, 4H), 7.27 (s, 2H), 7.19 (d, J = 7.6 Hz, 2H), 7.09–7.05 (m, 3H), 6.95–6.87 (m, 2H), 6.82–6.79 (m, 1H), 6.02–5.87 (m, 1H), 5.65–5.59 (m, 1H), 2.33 (s, 3H), 2.30 (s, 3H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 153.6, 153.4, 152.5, 146.9, 146.8, 144.0, 138.2, 137.7, 136.1, 133.1, 130.5, 129.7, 129.2, 129.0, 128.8, 128.5, 128.3, 128.2, 127.7, 127.6, 127.6, 125.9, 125.6, 124.7, 123.9, 123.3, 120.0, 114.1, 111.8, 107.1, 40.4, 21.7, 21.6; IR (KBr, ν, cm−1): 3245, 2924, 1734, 1625, 1484, 1447, 748, 695; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C39H30NO4S 608.1896; Found 608.1898.

3.15. N-(2-((3,5-Diphenylfuran-2-yl)(p-tolyl)methyl)benzofuran-3-yl)-4-methylbenzenesulfonamide (3o)

White solid (105.0 mg, 86% yield); m.p.: 200–202 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.64 (d, J = 7.6 Hz, 2H), 7.50–7.45 (m, 4H), 7.43 (s, 2H), 7.40–7.37 (m, 5H), 7.23 (d, J = 7.6 Hz, 1H), 7.17–7.13 (m, 1H), 7.10–7.04 (m, 4H), 7.00 (d, J = 8.0 Hz, 2H), 6.78 (s, 1H), 5.89 (s, 1H), 5.60 (s, 1H), 2.34 (s, 3H), 2.31 (s, 3H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 153.6, 153.3, 152.6, 146.9, 144.0, 137.0, 136.1, 134.7, 133.1, 130.4, 129.7, 129.4, 129.0, 128.8, 128.6, 128.4, 128.3, 127.7, 127.6, 125.7, 125.5, 124.7, 123.9, 123.2, 119.9, 113.1, 111.7, 107.0, 40.1, 21.6, 21.; IR (KBr, ν, cm−1): 3234, 2987, 1700, 1593, 1448, 1264, 863, 745; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C39H30NO4S 608.1896; Found 608.1899.

3.16. N-(2-((3-Chlorophenyl)(3,5-diphenylfuran-2-yl)methyl)benzofuran-3-yl)-4-methylbenzenesulfonamide (3p)

White solid (101.0 mg, 80% yield); m.p.: 170–172 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.62 (d, J = 7.6 Hz, 2H), 7.51–7.44 (m, 5H), 7.42 (s, 1H), 7.39–7.33 (m, 5H), 7.28 (s, 2H), 7.24–7.21 (m, 2H), 7.19–7.14 (m, 1H), 7.08–7.04 (m, 3H), 6.97 (d, J = 8.6 Hz, 1H), 6.77 (s, 1H), 5.83 (s, 1H), 5.62 (s, 1H), 2.31 (s, 3H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 153.7, 153.6, 152.0, 146.0, 144.2, 139.7, 137.0, 136.1, 134.3, 132.9, 130.3, 129.6, 129.1, 128.8, 128.6, 128.3, 127.8, 127.6, 126.7, 126.0, 125.7, 125.0, 123.9, 123.4, 119.8, 114.1, 111.8, 107.1, 39.9, 21.6; IR (KBr, ν, cm−1): 3245, 2945, 1698, 1603, 1454, 1398, 747, 691; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C38H27ClNO4S 628.1349; Found 628.1355.

3.17. N-(2-((2,6-Dichlorophenyl)(3,5-diphenylfuran-2-yl)methyl)benzofuran-3-yl)-4-methylbenzenesulfonamide (3q)

White solid (94.7 mg, 71% yield); m.p.: 131–132 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.64–7.56 (m, 5H), 7.40–7.37 (m, 3H), 7.31–7.28 (m, 3H), 7.24 (s, 2H), 7.21 (d, J = 10.0 Hz, 1H), 7.17–7.13 (m, 4H), 7.01–6.97 (m, 1H), 6.92 (d, J = 8.0 Hz, 2H), 6.79 (s, 1H), 6.45 (s, 1H), 6.31 (s, 1H), 2.10 (s, 3H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 153.6, 152.7, 149.4, 143.9, 143.6, 136.0, 135.9, 132.8, 132.7, 130.3, 129.7, 129.3, 129.0, 128.9, 128.4, 127.7, 127.5, 127.3, 127.1, 126.0, 125.9, 125.0, 123.6, 123.3, 120.4, 115.2, 111.7, 107.1, 38.6, 21.5; IR (KBr, ν, cm−1): 3254, 2920, 1697, 1506, 1496, 1456, 747, 691; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C38H26Cl2NO4S 662.0620; Found 662.0626.

3.18. N-(2-((2-Bromophenyl)(3,5-diphenylfuran-2-yl)methyl)benzofuran-3-yl)-4-methylbenzenesulfonamide (3r)

White solid (102.6 mg, 76% yield); m.p.: 163–164 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.68 (d, J = 7.6 Hz, 1H), 7.56 (d, J = 7.6 Hz, 2H), 7.46–7.40 (m, 4H), 7.38–7.33 (m, 5H),7.32–7.28 (m, 3H), 7.24–7.12 (m, 4H), 7.09–7.06 (m, 1H), 6.86 (d, J = 8.0 Hz, 2H), 6.79 (s, 1H), 6.07 (s, 1H), 5.85 (s, 1H), 2.14 (s, 3H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 153.7, 153.0, 149.9, 145.7, 143.7, 137.2, 135.6, 132.8, 132.7, 130.8, 130.3, 129.6, 129.1, 128.9, 128.7, 127.8, 127.7, 127.4, 127.2, 125.9, 125.4, 125.3, 124.9, 124.0, 123.7, 123.4, 120.7, 114.7, 111.6, 107.1, 41.3, 21.6;IR (KBr, ν, cm−1): 3256, 2922, 1699, 1603, 1495, 1447, 747, 691; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C38H27BrNO4S 672.0844; Found 672.0850.

3.19. N-(2-((3-Bromophenyl)(3,5-diphenylfuran-2-yl)methyl)benzofuran-3-yl)-4-methylbenzenesulfonamide (3s)

White solid (105.3 mg, 78% yield); m.p.: 178–179 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.65 (d, J = 8.0 Hz, 2H), 7.51–7.46 (m, 4H), 7.42 (d, J = 10.4 Hz, 3H), 7.39–7.33 (m, 5H), 7.29 (s, 1H), 7.25 (s, 1H), 7.18–7.14 (m, 4H), 7.07 (d, J = 8.0 Hz, 2H), 6.80–6.78 (m, 1H), 6.16 (s, 1H), 5.72–5.65 (m, 1H), 2.31 (s, 3H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 153.7, 153.6, 152.0, 146.0, 144.2, 140.1, 140.0, 136.0, 132.9, 131.5, 130.5, 130.3, 130.1, 129.8, 129.1, 128.8, 128.3, 127.8, 127.6, 127.2, 126.2, 125.7, 125.0, 123.9, 123.4, 122.6, 119.8, 114.2, 111.8, 107.1, 39.9, 21.7; IR (KBr, ν, cm−1): 3269, 2965, 1699, 1602, 1496, 1448, 748, 692; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C38H27BrNO4S 672.0844; Found 672.0850.

3.20. N-(2-((4-Bromophenyl)(3,5-diphenylfuran-2-yl)methyl)benzofuran-3-yl)-4-methylbenzenesulfonamide (3t)

White solid (112.1 mg, 83% yield); m.p.: 199–200 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.62 (d, J = 8.0 Hz, 2H), 7.49–7.45 (m, 3H), 7.43 (d, J = 3.6 Hz, 2H), 7.40 (d, J = 4.8 Hz, 3H), 7.36 (d, J = 6.8 Hz, 4H), 7.29 (s, 1H), 7.24 (d, J = 6.4 Hz,, 2H), 7.15–7.11 (m, 1H), 7.05 (d, J = 8.0 Hz, 2H), 7.00 (d, J = 8.4 Hz, 2H), 6.77 (s, 1H), 5.89 (s, 1H), 5.69 (s, 1H), 2.31 (s, 3H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 153.6, 153.6, 152.2, 146.1, 144.2, 136.9, 136.1, 132.9, 131.6, 130.3, 130.2, 129.7, 129.0, 128.8, 128.2, 127.8, 127.8, 127.6 125.9, 125.6, 124.9, 123.9, 123.4, 121.4, 119.7, 114.0, 111.8, 107.1, 39.8, 35.2, 31.1; IR (KBr, ν, cm−1): 3245, 2910, 1669, 1603, 1497, 1354, 747, 692; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C38H27BrNO4S 672.0844; Found 672.0853.

3.21. N-(2-((4-Bromophenyl)(3,5-diphenylfuran-2-yl)methyl)benzofuran-3-yl)-4-(tert-butyl)benzenesulfonamide (3u)

White solid (119.0 mg, 83% yield); m.p.: 203–205 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.67–7.52 (m, 2H), 7.51–7.46 (m, 3H), 7.44–7.40 (m, 5H), 7.36 (d, J = 7.2 Hz, 3H), 7.29 (d, J = 7.2 Hz, 3H), 7.24–7.21 (m, 2H), 7.13–7.08 (m, 2H), 7.06–7.04 (m, 2H), 6.80 (d, J = 12.4 Hz, 1H), 6.20 (s, 1H), 5.86 (s, 1H), 1.27 (s, 9H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 157.2, 153.6, 153.5, 152.7, 146.2, 146.1, 136.2, 132.9, 131.7, 130.4, 130.3, 129.0, 128.8, 128.3, 127.8, 127.7, 127.4, 126.1, 126.0, 125.6, 124.8, 123.9, 123.2, 121.4, 119.3, 114.0, 111.8, 107.1,39.8, 35.2, 31.1; IR (KBr, ν, cm−1): 3235, 2925, 1701, 1603, 1565, 1434, 762, 690; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C41H33BrNO4S 714.1314; Found 714.1320.

3.22. 4-Bromo-N-(2-((4-bromophenyl)(3,5-diphenylfuran-2-yl)methyl)benzofuran-3-yl)benzenesulfonamide (3v)

White solid (88.7 mg, 60% yield); m.p.: 181.2–182.9 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.62 (d, J = 8.0 Hz, 2H), 7.48 (d, J = 7.6 Hz, 2H), 7.44 (s, 2H), 7.42–7.40 (m, 3H), 7.38 (s, 5H), 7.35 (d, J = 7.6 Hz, 3H), 7.29 (s, 1H), 7.25 (s, 1H), 7.18–7.14 (m, 1H), 7.03 (d, J = 8.4 Hz, 2H), 6.78 (s, 1H), 5.99 (s, 1H), 5.65 (s, 1H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 153.6, 152.3, 146.0, 138.0, 136.7, 132.8, 132.4, 131.9, 130.2, 130.2, 129.1, 129.0, 128.9, 128.4, 128.2, 127.9, 127.8, 125.9, 125.4, 125.1, 123.9, 123.6, 121.6, 119.5, 113.6, 111.9, 107.1, 39.9; IR (KBr, ν, cm−1): 3235, 2925, 1710, 1653, 1595, 1493, 780, 692; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C37H24Br2NO4S 737.9772; Found 737.9778.
Mechanism details
Control experiment A
The following were successively added to a 10-mL pressure tube under air conditions: 4-methyl-2-phenylfuran (6, 0.1 mmol, 1.0 equiv, 15.8 mg), aurone-derived azadiene (2a, 0.1 mmol, 1.0 equiv, 37.5 mg), JohnPhosAu(MeCN)SbF6 (2 mol%, 1.54 mg), 1,2-dichloroethane (1.0 mL). The mixture was stirred at room temperature for about 10 min. After the reaction was completed (indicated by TLC, petroleum ether:ethyl acetate = 15:1), the reaction mixture was concentrated via vacuum distillation and purified via flash column chromatography to afford the desired pure product (3a, 44.5 mg, 84% yield) as an orange solid.
Control experiment B
The following were successively added to a 10-mL pressure tube under air conditions: 4-methyl-2-phenylfuran (6, 0.1 mmol, 1.0 equiv, 15.8 mg), aurone-derived azadienes (2a, 0.1 mmol, 1.0 equiv, 37.5 mg), 1,2-dichloroethane (1.0 mL). The desired product 3a was not detected by TLC.
General procedure for the synthesis of products 5a–5l
The following were successively added to a 10-mL pressure tube under air conditions, 2-methyl-4-phenylbut-3-yne-1,2-diol (1a, 0.2 mmol, 2.0 equiv, 31.2 mg), 4-benzylidene-2,6-di-tert-butylcyclohexa-2,5-dienone (2a, 0.2 mmol, 1.0 equiv, 58.8 mg), JohnPhosAu(MeCN)SbF6 (2.0 mol%, 3.08 mg), 1,2-dichloroethane (2.0 mL). The mixture was stirred at room temperature for about 4 h. After the reaction was completed (indicated by TLC, petroleum ether:ethyl acetate = 20:1), the reaction mixture was concentrated via vacuum distillation and purified via flash column chromatography to afford the desired pure product (3a, 82.4 mg, 91% yield) as a white solid.

3.23. 2,6-Di-tert-butyl-4-((3-methyl-5-phenylfuran-2-yl)(phenyl)methyl)phenol (5a)

White solid (82.3 mg, 91% yield); m.p.: 150–151 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.62 (d, J = 8.0 Hz, 2H), 7.36–7.31 (m, 3H), 7.29 (s, 3H), 7.21 (d, J = 5.6 Hz, 2H), 7.19 (s, 2H), 6.51 (s, 1H), 5.41 (s, 1H), 5.13 (s, 1H), 2.00 (s, 3H), 1.43 (s, 18H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 152.5, 151.7, 151.2, 143.1, 135.7, 132.4, 131.3, 128.8, 128.7, 128.4, 126.8, 126.3, 125.8, 123.5, 117.7, 108.8, 48.8, 34.5, 30.5, 10.4; IR (KBr, ν, cm−1): 3633, 2958, 1797, 1601, 1435, 1363, 774, 692; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C33H35O2 451.2637; Found 451.2639.

3.24. 2,6-Di-tert-butyl-4-((3-methyl-5-phenylfuran-2-yl)(o-tolyl)methyl)1phenol (5b)

White solid (75.7 mg, 81% yield); m.p.: 135–136 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.57 (d, J = 7.6Hz, 2H), 7.34–7.30 (m, 2H), 7.20–7.15 (m, 5H), 7.03 (s, 2H), 6.47 (s, 1H), 5.56 (s, 1H), 5.09 (s, 1H), 2.32 (s, 3H), 1.84 (s, 3H), 1.39 (s, 18H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 152.3, 151.4, 150.8, 141.1, 136.2, 135.6, 131.7, 131.3, 130.3, 129.0, 128.6, 126.7, 126.4, 126.0, 125.7, 123.4, 117.7, 109.0, 45.8, 34.4, 30.4, 20.0, 10.2; IR (KBr, ν, cm−1): 3567, 2957, 1795, 1602, 1510, 1365, 775, 690; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C33H37O2 465.2794; Found 465.2796.

3.25. 2,6-Di-tert-butyl-4-((3-methyl-5-phenylfuran-2-yl)(p-tolyl)methyl)phenol (5c)

White solid (77.5 mg, 83% yield); m.p.: 171–173 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.55 (d, J = 7.6 Hz, 2H), 7.30–7.26 (m, 2H), 7.16–7.12 (m, 5H), 7.03 (s, 2H), 6.45 (s, 1H), 5.30 (s, 1H), 5.06 (s, 1H), 2.27 (s, 3H), 1.93 (s, 3H), 1.36 (s, 18H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 152.4, 151.3, 142.9, 137.8, 135.6, 132.4, 129.5, 128.6, 128.2, 127.2, 126.7, 126.1, 125.8, 123.4, 117.5, 108.8, 48.7, 34.5, 30.4, 21.6, 10.3; IR (KBr, ν, cm−1): 3632, 2958, 1748, 1607, 1507, 1366, 775, 759; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C33H37O2 465.2794; Found 465.2795.

3.26. 2,6-Di-tert-butyl-4-((3,4-dimethylphenyl)(3-methyl-5-phenylfuran-2-yl)methyl)phenol (5d)

White solid (67.3 mg, 70% yield); m.p.: 148–150 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.62 (d, J = 7.6 Hz, 2H), 7.36–7.33 (m, 2H), 7.21 (s, 4H), 7.06 (s, 2H), 6.50 (s, 1H), 5.33 (s, 1H), 5.12 (s, 1H), 2.24 (s, 6H), 2.00 (s, 3H), 1.43 (s, 18H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 152.4, 151.5, 140.4, 136.3, 135.6, 134.4, 132.6, 131.4, 130.0, 129.6, 128.6, 126.7, 126.0, 125.8, 123.4, 117.4, 108.8, 48.4, 34.5, 30.5, 20.0, 19.5, 10.4; IR (KBr, ν, cm−1): 3632, 2959, 1796, 1601, 1489, 1363, 774, 760; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C34H39O2 479.2950; Found 479.2949.

3.27. 2,6-Di-tert-butyl-4-((4-methoxyphenyl)(3-methyl-5-phenylfuran-2-yl)methyl)phenol (5e)

White solid (57.8 mg, 60% yield); m.p.: 153–155 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.60 (d, J = 8.0 Hz, 2H), 7.35–7.31 (m, 2H), 7.21–7.15 (m, 5H), 6.83 (d, J = 8.2 Hz, 2H), 6.49 (s, 1H), 5.34 (s, 1H), 5.10 (s, 1H), 3.79 (s, 3H), 1.97 (s, 3H), 1.41 (s, 18H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 158.1, 152.4, 151.5, 135.6, 135.3, 132.7, 131.3, 130.3, 129.7, 128.6, 126.7, 125.7, 123.4, 117.4, 113.7, 108.8, 55.3, 47.9, 34.4, 30.4, 10.3; IR (KBr, ν, cm−1): 3625, 2957, 1796, 1601, 1488, 1364, 775, 761; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C33H37O3 481.2743; Found 481.2740.

3.28. 2,6-Di-tert-butyl-4-((3-methoxyphenyl)(3-methyl-5-phenylfuran-2-yl)methyl)phenol (5f)

White solid (84.3 mg, 87% yield); m.p.: 158–160 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.62 (d, J = 7.8 Hz, 2H), 7.37–7.33 (m, 2H), 7.25–7.19 (m, 4H), 6.89–6.85 (m, 2H), 6.77 (d, J = 8.4 Hz, 1H), 6.51 (s, 1H), 5.38 (s, 1H), 5.14 (s, 1H), 3.77 (s, 3H), 2.00 (s, 3H), 1.43 (s, 18H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 159.6, 152.5, 151.7, 151.1, 144.7, 135.7, 132.1, 131.3, 129.2, 128.6, 126.8, 125.8, 123.4, 121.3, 117.7, 114.8, 111.5, 108.8, 48.71, 34.5, 30.4, 10.4; IR (KBr, ν, cm−1): 3566, 2957, 1795, 1606, 1335, 1366, 775, 708; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C33H37O3 481.2743; Found 481.2745.

3.29. 2,6-Di-tert-butyl-4-((4-fluorophenyl)(3-methyl-5-phenylfuran-2-yl)methyl)phenol (5g)

White solid (73.3 mg, 78% yield); m.p.: 177–179 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.58 (d, J = 8.0 Hz, 2H), 7.35–7.31 (m, 2H), 7.22–7.18 (m, 3H), 7.11 (s, 2H), 7.00–6.95 (m, 2H), 6.49 (s, 1H), 5.36 (s, 1H), 5.12 (s, 1H), 1.97 (s, 3H), 1.40 (s, 18H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 161.5 (JCF1 = 242.8 Hz), 152.5, 151.7, 150.8, 138.7 (JCF4 = 3.1 Hz), 135.8, 132.2, 131.2, 130.2 (JCF3 = 7.9 Hz), 128.6, 126.9, 125.6, 123.4, 117.7, 115.0 (JCF2 = 21.1 Hz), 108.7, 47.9, 34.5, 30.4, 10.4; IR (KBr, ν, cm−1): 3626, 2962, 1796, 1608, 1435, 1366, 774, 701; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C32H34FO2 469.2543; Found 469.2547.

3.30. 2,6-Di-tert-butyl-4-((4-chlorophenyl)(3-methyl-5-phenylfuran-2-yl)methyl)phenol (5h)

White solid (87.7 mg, 90% yield); m.p.: 162–164 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.60 (d, J = 6.8 Hz, 2H), 7.37–7.33 (m, 2H), 7.29 (s, 1H), 7.24–7.18 (m, 4H), 7.15 (s, 2H), 6.52 (s, 1H), 5.37 (s, 1H), 5.15 (s, 1H), 2.00 (s, 3H), 1.43 (s, 18H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 152.7, 151.9, 150.5, 141.7, 135.9, 132.1, 131.9, 131.2, 130.1, 128.7, 128.5, 127.0, 125.7, 123.5, 117.9, 108.8, 48.1, 34.5, 30.4, 10.3; IR (KBr, ν, cm−1): 3566, 2957, 1704, 1601, 1450, 1366, 774, 749; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C32H34ClO2 485.2247; Found 485.2249.

3.31. 2,6-Di-tert-butyl-4-((3,4-dichlorophenyl)(3-methyl-5-phenylfuran-2-yl)methyl)phenol (5i)

White solid (91.9 mg, 88% yield); m.p.: 179–181 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.60 (d, J = 8.0 Hz, 2H), 7.38–7.34 (m, 4H), 7.25–7.21 (m, 1H), 7.14–7.09 (m, 3H), 6.52 (s, 1H), 5.34 (s, 1H), 5.18 (s, 1H), 2.01 (s, 3H), 1.43 (s, 18H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 152.8, 152.1, 149.8, 143.5, 136.0, 132.3, 131.2, 131.0, 130.7, 130.4, 130.2, 128.7, 128.2, 127.1, 125.6, 123.5, 118.2, 108.8, 47.9, 34.5, 30.4, 10.3. IR (KBr, ν, cm−1): 3632, 2958, 1680, 1601, 1434, 1363, 758, 699; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C32H33Cl2O2 519.1858; Found 519.1857.

3.32. 2,6-Di-tert-butyl-4-((3-methyl-5-(p-tolyl)furan-2-yl)(phenyl)methyl)phenol (5j)

White solid (72.3 mg, 75% yield); m.p.: 163–165 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.53 (d, J = 7.8 Hz, 2H), 7.31–7.29 (m, 3H), 7.25–7.16 (m, 4H), 6.88 (d, J = 8.0 Hz, 2H), 6.36 (s, 1H), 5.38 (s, 1H), 5.11 (s, 1H), 3.82 (s, 3H), 1.97 (s, 3H), 1.41 (s, 18H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 158.7, 152.4, 151.7, 150.4, 143.2, 135.6, 132.5, 128.6, 128.3, 126.2, 125.8, 124.9, 124.5, 117.5, 114.1, 107.2, 55.4, 48.7, 34.5, 30.4, 10.3; IR (KBr, ν, cm−1): 3632, 2960, 1796, 1601, 1435, 1362, 809, 760; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C33H37O3 481.2743; Found 481.2740.

3.33. 2,6-Di-tert-butyl-4-((3-ethyl-5-phenylfuran-2-yl)(phenyl)methyl)phenol (5k)

White solid (79.4 mg, 85% yield); m.p.: 138–140 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): 7.55 (d, J = 7.8 Hz, 2H), 7.37–7.31 (m, 5H), 7.12–7.18 (m, 5H), 6.46 (s, 1H), 5.40 (s, 1H), 5.13 (s, 1H), 2.66 (q, J = 7.2 Hz, 2H), 1.44 (s, 18H), 1.26 (t, J = 7.6 Hz, 3H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 152.4, 151.9, 150.7, 143.2, 143.0, 135.6, 132.4, 128.9, 128.7, 128.3, 128.1, 126.3, 125.80, 123.5, 117.5, 108.0, 48.7, 34.5, 30.4, 15.7, 10.3; IR (KBr, ν, cm−1): 3632, 2958, 1796, 1604, 1435, 1363, 774, 691; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C33H37O2 465.2794; Found 465.2798.

3.34. 2,6-Di-tert-butyl-4-((3,5-diphenylfuran-2-yl)(phenyl)methyl)phenol (5l)

White solid (89.4 mg, 87% yield); m.p.: 141–143 °C; 1H NMR (400 MHz, CDCl3) (δ, ppm): δ 7.63 (d, J = 7.8 Hz, 2H), 7.38–7.33 (m, 5H), 7.32 (d, J = 7.5 Hz, 1H), 7.25 (s, 5H), 7.22–7.15 (m, 4H), 6.76 (s, 1H), 5.50 (s, 1H), 5.07 (s, 1H), 1.36 (s, 18H); 13C NMR (100 MHz, CDCl3) (δ, ppm): 152.5, 151.2, 143.1, 135.7, 134.1, 132.5, 131.0, 128.8, 128.71, 128.68, 128.41, 128.35, 127.2, 127.0, 126.4, 125.9, 124.7, 123.7, 107.0, 48.8, 34.5, 30.4; IR (KBr, ν, cm−1): 3632, 2957, 1709, 1556, 1499, 1363, 774, 901; HRMS (ESI-TOF) m/z: [M − H]− Calcd. for C37H37O2 513.2794; Found 513.2799.

4. Conclusions

In summary, a new gold self-relay catalysis consisting of intramolecular annulation and intermolecular Michael addition was accomplished, starting from easily preformed 3-yne-1,2-diols and aurone-derived azadienes (or p-QMs). The overall process was governed by the π- and σ-Lewis acid capability of gold complexes, resulting in a wide range of synthetically important unsymmetrical furanized triarylmethanes in good yields. The current catalytic strategy features good substrate scope, high functional group tolerance, and mild conditions. Furthermore, the reaction proceeded smoothly without any inert atmosphere protection, thus highlighting the good oxygen resistance and simple operation process. Further the application of gold(I) self-relay catalysis in assembling functionalized molecules of biological importance is underway in our laboratory.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/catal13071051/s1.

Author Contributions

Methodology, Q.R., Y.Z. and X.-Y.G.; writing—original draft preparation, Q.R.; experimental data processing, Q.R. and Y.-P.L.; writing—review and editing, W.-J.H. and B.J.; supervision, W.-J.H. and B.J.; project administration, B.J. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the National Natural Science Foundation of China, grant number 21971090 and 22271123.

Data Availability Statement

Data supporting the reported results can be found in the Supplementary Materials.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Parai, M.K.; Panda, G.; Chaturvedi, V.; Manju, Y.K.; Sinha, S. Thiophene containing triarylmethanes as antitubercular agents. Bioorg. Med. Chem. Lett. 2008, 18, 289–292. [Google Scholar] [CrossRef] [PubMed]
  2. Al-Qawasmeh, R.A.; Lee, Y.; Cao, M.-Y.; Gu, X.; Vassilakos, A.; Wright, J.A.; Young, A. Triaryl methane derivatives as antiproliferative agents. Bioorg. Med. Chem. Lett. 2004, 14, 347–350. [Google Scholar] [CrossRef] [PubMed]
  3. Shchepinov, M.S.; Korshun, V.A. Recent applications of bifunctional trityl groups. Chem. Soc. Rev. 2003, 32, 170–180. [Google Scholar] [CrossRef]
  4. Wulff, H.; Zhorov, B.S. K+ Channel Modulators for the Treatment of Neurological Disorders and Autoimmune Diseases. Chem. Rev. 2008, 108, 1744–1773. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  5. Esquivias, J.; Gomez Arrayas, R.; Carretero, J.C. A copper(II)-catalyzed aza-Friedel-Crafts reaction of N-(2-pyridyl)sulfonyl aldimines: Synthesis of unsymmetrical diaryl amines and triaryl methanes. Angew. Chem. Int. Ed. 2006, 45, 629–633. [Google Scholar] [CrossRef]
  6. Li, Z.; Duan, Z.; Kang, J.; Wang, H.; Yu, L.; Wu, Y. A simple access to triarylmethane derivatives from aromatic aldehydes and electron-rich arenes catalyzed by FeCl3. Tetrahedron 2008, 64, 1924–1930. [Google Scholar] [CrossRef]
  7. Thirupathi, P.; Kim, S.S. Fe(ClO4)3·xH2O-Catalyzed direct C–C bond forming reactions between secondary benzylic alcohols with different types of nucleophiles. Tetrahedron 2010, 66, 2995–3003. [Google Scholar] [CrossRef]
  8. Hikawa, H.; Suzuki, H.; Yokoyama, Y.; Azumaya, I. Chemoselective Benzylation of Unprotected Anthranilic Acids with Benzhydryl Alcohols by Water-Soluble Au(III)/TPPMS in Water. J. Org. Chem. 2013, 78, 6714–6720. [Google Scholar] [CrossRef]
  9. Singh, P.; Dinda, S.K.; Shagufta, P.G. Synthetic approach towards trisubstituted methanes and a chiral tertiary α-hydroxyaldehyde, a possible intermediate for tetrasubstituted methanes. RSC Adv. 2013, 3, 12100–12103. [Google Scholar] [CrossRef]
  10. Mondal, S.; Panda, G. Synthetic methodologies of achiral diarylmethanols, diaryl and triarylmethanes (TRAMs) and medicinal properties of diaryl and triarylmethanes-an overview. RSC Adv. 2014, 4, 28317–28358. [Google Scholar] [CrossRef]
  11. Nambo, M.; Crudden, C.M. Recent Advances in the Synthesis of Triarylmethanes by Transition Metal Catalysis. ACS Catal. 2015, 5, 4734–4742. [Google Scholar] [CrossRef]
  12. Yu, J.-Y.; Kuwano, R. Suzuki-Miyaura Coupling of Diarylmethyl Carbonates with Arylboronic Acids:  A New Access to Triarylmethanes. Org. Lett. 2008, 10, 973–976. [Google Scholar] [CrossRef]
  13. Nambo, M.; Yar, M.; Smith, J.D.; Crudden, C.M. The Concise Synthesis of Unsymmetric Triarylacetonitriles via Pd-Catalyzed Sequential Arylation: A New Synthetic Approach to Tri- and Tetraarylmethanes. Org. Lett. 2015, 17, 50–53. [Google Scholar] [CrossRef]
  14. Tabuchi, S.; Hirano, K.; Satoh, T.; Miura, M. Synthesis of Triarylmethanes by Palladium-Catalyzed C–H/C–O Coupling of Oxazoles and Diarylmethanol Derivatives. J. Org. Chem. 2014, 79, 5401–5411. [Google Scholar] [CrossRef]
  15. Xia, Y.; Hu, F.; Liu, Z.; Qu, P.; Ge, R.; Ma, C.; Zhang, Y.; Wang, J. Palladium-Catalyzed Diarylmethyl C(sp3)-C(sp2) Bond Formation: A New Coupling Approach toward Triarylmethanes. Org. Lett. 2013, 15, 1784–1787. [Google Scholar] [CrossRef]
  16. Matthew, S.C.; Glasspoole, B.W.; Eisenberger, P.; Crudden, C.M. Synthesis of Enantiomerically Enriched Triarylmethanes by Enantiospecific Suzuki–Miyaura Cross-Coupling Reactions. J. Am. Chem. Soc. 2014, 136, 5828–5831. [Google Scholar] [CrossRef]
  17. Cao, X.; Sha, S.-C.; Li, M.; Kim, B.-S.; Morgan, C.; Huang, R.; Yang, X.; Walsh, P.J. Nickel-catalyzed arylation of heteroaryl-containing diarylmethanes: Exceptional reactivity of the Ni(NIXANTPHOS)-based catalyst. Chem. Sci. 2016, 7, 611–618. [Google Scholar] [CrossRef] [Green Version]
  18. Zhang, J.; Bellomo, A.; Creamer, A.D.; Dreher, S.D.; Walsh, P.J. Palladium-Catalyzed C(sp3)-H Arylation of Diarylmethanes at Room Temperature: Synthesis of Triarylmethanes via Deprotonative-Cross-Coupling Processes. J. Am. Chem. Soc. 2012, 134, 13765–13772. [Google Scholar] [CrossRef]
  19. Shi, B.-F.; Maugel, N.; Zhang, Y.-H.; Yu, J.-Q. PdII-catalyzed enantioselective activation of C(sp2)-H and C(sp3)-H bonds using monoprotected amino acids as chiral ligands. Angew. Chem. Int. Ed. 2008, 47, 4882–4886. [Google Scholar] [CrossRef]
  20. Niwa, T.; Yorimitsu, H.; Oshima, K. Palladium-Catalyzed Direct Arylation of Aryl(azaaryl)methanes with Aryl Halides Providing Triarylmethanes. Org. Lett. 2007, 9, 2373–2375. [Google Scholar] [CrossRef]
  21. Nambo, M.; Crudden, C.M. Modular Synthesis of Triarylmethanes through Palladium-Catalyzed Sequential Arylation of Methyl Phenyl Sulfone. Angew. Chem. Int. Ed. 2014, 53, 742–746. [Google Scholar] [CrossRef] [PubMed]
  22. Zhang, J.; Bellomo, A.; Trongsiriwat, N.; Jia, T.; Carroll, P.J.; Dreher, S.D.; Tudge, M.T.; Yin, H.; Robinson, J.R.; Schelter, E.J.; et al. NiXantphos: A Deprotonatable Ligand for Room-Temperature Palladium-Catalyzed Cross-Couplings of Aryl Chlorides. J. Am. Chem. Soc. 2014, 136, 6276–6287. [Google Scholar] [CrossRef] [PubMed]
  23. Zhang, Z.; Wang, H.; Qiu, N.; Kong, Y.; Zeng, W.; Zhang, Y.; Zhao, J. Synthesis of Triarylmethanes via Palladium-Catalyzed Suzuki Coupling of Trimethylammonium Salts and Arylboronic Acids. J. Org. Chem. 2018, 83, 8710–8715. [Google Scholar] [CrossRef] [PubMed]
  24. Zhao, X.; Wu, G.; Zhang, Y.; Wang, J. Copper-Catalyzed Direct Benzylation or Allylation of 1,3-Azoles with N-Tosylhydrazones. J. Am. Chem. Soc. 2011, 133, 3296–3299. [Google Scholar] [CrossRef]
  25. Rao, H.S.P.; Rao, A.V.B. Copper-mediated arylation with arylboronic acids: Facile and modular synthesis of triarylmethanes. Beilstein J. Org. Chem. 2016, 12, 496–504. [Google Scholar] [CrossRef] [Green Version]
  26. Tobisu, M.; Yasutome, A.; Kinuta, H.; Nakamura, K.; Chatani, N. 1,3-Dicyclohexylimidazol-2-ylidene as a Superior Ligand for the Nickel-Catalyzed Cross-Couplings of Aryl and Benzyl Methyl Ethers with Organoboron Reagents. Org. Lett. 2014, 16, 5572–5575. [Google Scholar] [CrossRef]
  27. Taylor, B.L.H.; Harris, M.R.; Jarvo, E.R. Synthesis of Enantioenriched Triarylmethanes by Stereospecific Cross-Coupling Reactions. Angew. Chem. Int. Ed. 2012, 51, 7790–7793. [Google Scholar] [CrossRef]
  28. Harris, M.R.; Hanna, L.E.; Greene, M.A.; Moore, C.E.; Jarvo, E.R. Retention or Inversion in Stereospecific Nickel-Catalyzed CrossCoupling of Benzylic Carbamates with Arylboronic Esters: Control of Absolute Stereochemistry with an Achiral Catalyst. J. Am. Chem. Soc. 2013, 135, 3303–3306. [Google Scholar] [CrossRef] [Green Version]
  29. Zhou, Q.; Srinivas, H.D.; Dasgupta, S.; Watson, M.P. Nickel-Catalyzed Cross-Couplings of Benzylic Pivalates with Arylboroxines: Stereospecific Formation of Diarylalkanes and Triarylmethanes. J. Am. Chem. Soc. 2013, 135, 3307–3310. [Google Scholar] [CrossRef] [Green Version]
  30. Li, Y.-Z.; Li, B.-J.; Lu, X.-Y.; Lin, S.; Shi, Z.-J. Cross Dehydrogenative Arylation (CDA) of a Benzylic C−H Bond with Arenes by Iron Catalysis. Angew. Chem. Int. Ed. 2009, 48, 3817–3820. [Google Scholar] [CrossRef]
  31. Cao, L.-L.; Ye, Z.-S.; Jiang, G.-F.; Zhou, Y.-G. Rhodium-Catalyzed Addition of Boronic Acids to Vinylogous Imines Generated in situ from Sulfonylindoles. Adv. Synth. Catal. 2011, 353, 3352–3356. [Google Scholar] [CrossRef]
  32. Huang, Y.; Hayashi, T. Asymmetric Synthesis of Triarylmethanes by Rhodium-Catalyzed Enantioselective Arylation of Diarylmethylamines with Arylboroxines. J. Am. Chem. Soc. 2015, 137, 7556–7559. [Google Scholar] [CrossRef]
  33. Parra, A.; Tortosa, M. para-Quinone Methide: A New Player in Asymmetric Catalysis. ChemCatChem 2015, 7, 1524–1526. [Google Scholar] [CrossRef] [Green Version]
  34. Singh, G.; Pandey, R.; Pankhade, Y.A.; Fatma, S.; Anand, R.V. Construction of Oxygen- and Nitrogen-based Heterocycles from p-Quinone Methides. Chem. Rec. 2021, 21, 4150–4173. [Google Scholar] [CrossRef]
  35. Li, W.; Xu, X.; Zhang, P.; Li, P. Recent Advances in the Catalytic Enantioselective Reactions of para-Quinone Methides. Chem.-Asian J. 2018, 13, 2350–2359. [Google Scholar] [CrossRef]
  36. Lima, C.G.S.; Pauli, F.P.; Costa, D.C.S.; de Souza, A.S.; Forezi, L.S.M.; Ferreira, V.F.; de Carvalho da Silva, F. para-Quinone Methides as Acceptors in 1,6-Nucleophilic Conjugate Addition Reactions for the Synthesis of Structurally Diverse Molecules. Eur. J. Org. Chem. 2020, 18, 2650–2692. [Google Scholar] [CrossRef]
  37. Wang, J.-Y.; Hao, W.-J.; Tu, S.-J.; Jiang, B. Recent developments in 1,6-addition reactions of para-quinone methides (p-QMs). Org. Chem. Front. 2020, 7, 1743–1778. [Google Scholar] [CrossRef]
  38. Liu, X.; Wu, X.; Zhang, L.; Lin, X.; Huang, D. Recent Advances in Triarylmethane Synthesis. Synthesis 2020, 52, 2311–2329. [Google Scholar]
  39. Ye, L.-W.; Zhu, X.-Q.; Sahani, R.L.; Xu, Y.; Qian, P.-C.; Liu, R.-S. Nitrene Transfer and Carbene Transfer in Gold Catalysis. Chem. Rev. 2021, 121, 9039–9112. [Google Scholar] [CrossRef]
  40. Lu, Z.; Li, T.; Mudshinge, S.R.; Xu, B.; Hammond, G.B. Optimization of Catalysts and Conditions in Gold(I) Catalysis-Counterion and Additive Effects. Chem. Rev. 2021, 121, 8452–8477. [Google Scholar] [CrossRef]
  41. Zheng, Z.; Ma, X.; Cheng, X.; Zhao, K.; Gutman, K.; Li, T.; Zhang, L. Homogeneous Gold-Catalyzed Oxidation Reactions. Chem. Rev. 2021, 121, 8979–9038. [Google Scholar] [CrossRef] [PubMed]
  42. Li, D.; Zang, W.; Bird, M.J.; Hyland, C.J.T.; Shi, M. Gold-Catalyzed Conversion of Highly Strained Compounds. Chem. Rev. 2021, 121, 8685–8755. [Google Scholar] [CrossRef] [PubMed]
  43. Mato, M.; Franchino, A.; Garca-Morales, C.; Echavarren, A.M. Gold-Catalyzed Synthesis of Small Rings. Chem. Rev. 2021, 121, 8613–8684. [Google Scholar] [CrossRef] [PubMed]
  44. Reyes, R.L.; Iwai, T.; Sawamura, M. Construction of Medium-Sized Rings by Gold Catalysis. Chem. Rev. 2021, 121, 8926–8947. [Google Scholar] [CrossRef]
  45. Witzel, S.; Hashmi, A.S.K.; Xie, J. Light in Gold Catalysis. Chem. Rev. 2021, 121, 8868–8925. [Google Scholar] [CrossRef]
  46. Campeau, D.; León-Rayo, D.F.; Mansour, A.; Muratov, K.; Gagosz, F. Gold-Catalyzed Reactions of Specially Activated Alkynes, Allenes, and Alkenes. Chem. Rev. 2021, 121, 8756–8867. [Google Scholar] [CrossRef]
  47. Wang, T.; Hashmi, A.S.K. 1,2-Migrations onto Gold Carbene Centers. Chem. Rev. 2021, 121, 8948–8978. [Google Scholar] [CrossRef]
  48. Gobé, V.; Retailleau, P.; Guinchard, X. Self-Relay Gold (I)-Catalyzed Pictet-Spengler/Cyclization Cascade Reaction for the Rapid Elaboration of Pentacyclic Indole Derivatives. Chem.-Eur. J. 2015, 21, 17587–17590. [Google Scholar] [CrossRef]
  49. Fustero, S.; Miró, J.; Sánchez-Roselló, M.; del Pozo, C. Tandem Gold Self-Relay Catalysis for the Synthesis of 2,3-Dihydropyridin-4(1H)-ones: Combination of σ and π Lewis Acid Properties of Gold Salts. Chem.-Eur. J. 2014, 20, 14126–14131. [Google Scholar] [CrossRef]
  50. Shi, Z.; Mao, W.; Yang, Z.; Sun, S.; Tung, C.-H.; Xu, Z. Au-catalyzed neighboring hydroxymethyl group directed cycloaddition of alkyne with diazadienes: Synthesis of polysubstituted pyrroles. Chin. Chem. Lett. 2023, 34, 107488. [Google Scholar] [CrossRef]
  51. Meng, F.-T.; Wang, Y.-N.; Qin, X.-Y.; Li, S.-J.; Li, J.; Hao, W.-J.; Tu, S.-J.; Lan, Y.; Jiang, B. Azoarene activation for Schmidt-type reaction and mechanistic insights. Nat. Commun. 2022, 13, 7393. [Google Scholar] [CrossRef]
  52. Meng, F.-T.; Chen, J.-L.; Qin, X.-Y.; Zhang, T.-S.; Tu, S.-J.; Jiang, B.; Hao, W.-J. Gold self-relay catalysis for accessing functionalized cyclopentenones bearing an all-carbon quaternary stereocenter. Org. Chem. Front. 2022, 9, 140–146. [Google Scholar] [CrossRef]
  53. Meng, F.-T.; Qin, X.-Y.; Li, J.; Zhang, T.-S.; Tu, S.-J.; Jiang, B.; Hao, W.-J. Gold Self-Relay Catalysis Enabling [3,3]-Sigmatropic Rearrangement/Nazarov Cyclization and Allylic Alkylation Cascade for Constructing All-Carbon Quaternary Stereocenters. Chin. J. Chem. 2022, 40, 687–692. [Google Scholar] [CrossRef]
  54. Hao, M.-Y.; Zhang, Y.; Lin, N.; Fu, R.; Ji, X.-S.; Jiang, B.; Tu, S.-J.; Hao, W.-J. Gold self-relay catalysis enabling annulative oxygenation of propargylic alcohols with O-nucleophiles. Chem. Commun. 2023, 59, 4032–4035. [Google Scholar] [CrossRef]
  55. Egi, M.; Azechi, K.; Akai, S. Cationic Gold(I)-Mediated Intramolecular Cyclization of 3-Alkyne-1,2-diols and 1-Amino-3-alkyn-2-ols: A Practical Route to Furans and Pyrroles. Org. Lett. 2009, 11, 5002–5005. [Google Scholar] [CrossRef]
  56. Aponick, A.; Li, C.-Y.; Malinge, J.; Marques, E.F. An Extremely Facile Synthesis of Furans, Pyrroles, and Thiophenes by the Dehydrative Cyclization of Propargyl Alcohols. Org. Lett. 2009, 11, 4624–4627. [Google Scholar] [CrossRef]
  57. Liu, W.-T.; Xu, Z.-L.; Mou, X.-Q.; Zhang, B.-H.; Bao, W.; Wang, S.-H.; Lee, D.; Lei, L.-S.; Zhang, K. The synthesis of cycloalka[b]furans via an Au(I)-catalyzed tandem reaction of 3-yne-1,2-diols. Org. Biomol. Chem. 2017, 15, 6333–6337. [Google Scholar] [CrossRef]
  58. Wang, D.; Wang, S.-C.; Hao, W.-J.; Tu, S.-J.; Jiang, B. Dual Palladium/Scandium Catalysis toward Rotationally Hindered C3-Naphthylated Indoles from β-Alkynyl Ketones and o-Alkynyl Anilines. Chin. J. Chem. 2021, 39, 106–114. [Google Scholar] [CrossRef]
  59. Chen, L.-Q.; Zhu, C.-F.; Zhang, S.; Liu, B.-Y.; Tu, S.-J.; Hao, W.-J.; Jiang, B. Palladium-catalyzed annulative allylic alkylation for regioselective construction of indole-fused medium-sized cyclic ethers. Chin. Chem. Lett. 2023, 34, 108398. [Google Scholar] [CrossRef]
  60. Wang, D.; Wang, S.-C.; Hao, W.-J.; Tu, S.-J.; Jiang, B. Selective Syntheses of Benzo[b]carbazoles and C3-Substituted Indoles via Tunable Catalytic Annulations of β-Alkynyl Ketones with Indoles. Adv. Synth. Catal. 2020, 362, 3416–3422. [Google Scholar] [CrossRef]
  61. Li, X.; Villar-Yanez, A.; Tounzoua, C.N.; Benet-Buchholz, J.; Grignard, B.; Bo, C.; Detrembleur, C.; Kleij, A.W. Cascade Transformation of Carbon Dioxide and Alkyne-1,n-diols into Densely Substituted Cyclic Carbonates. ACS Catal. 2022, 12, 2854–2860. [Google Scholar] [CrossRef]
  62. Gabriele, B.; Veltri, L.; Plastina, P.; Mancuso, R.; Vetere, M.V.; Maltese, V. Copper-Catalyzed Synthesis of Substituted Furans and Pyrroles by Heterocyclodehydration and Tandem Heterocyclodehydration–Hydration of 3-Yne-1,2-diols and 1-Amino-3-yn-2-ol Derivatives. J. Org. Chem. 2013, 78, 4919–4928. [Google Scholar] [CrossRef] [PubMed]
  63. Minkler, S.R.K.; Isley, N.A.; Lippincott, D.J.; Krause, N.; Lipshutz, B.H. Leveraging the Micellar Effect: Gold-Catalyzed Dehydrative Cyclizations in Water at Room Temperature. Org. Lett. 2014, 16, 724–726. [Google Scholar] [CrossRef] [PubMed] [Green Version]
  64. Zhu, C.-F.; Chen, L.-Q.; Hao, W.-J.; Cui, C.-C.; Tu, S.-J.; Jiang, B. Diastereoselective Synthesis of 1,2-Dihydrobenzofuro[3,2-b]pyridines via a Carbon-Carbon Double Bond Cleavage–Rearrangement Cascade. Org. Lett. 2021, 23, 2654–2658. [Google Scholar] [CrossRef]
  65. Yang, M.; Han, H.; Jiang, H.; Ye, S.; Fan, X.; Wu, J. Photoinduced reaction of potassium alkyltrifluoroborates, sulfur dioxide and para-quinone methides via radical 1,6-addition. Chin. Chem. Lett. 2021, 32, 3535–3538. [Google Scholar] [CrossRef]
Catalysts 13 01051 sch001 550
Scheme 1. Profiles for the synthesis of unsymmetrical triarylmethanes.
Scheme 1. Profiles for the synthesis of unsymmetrical triarylmethanes.
Catalysts 13 01051 sch001
Catalysts 13 01051 sch002 550
Scheme 2. Substrate scope for forming triarylmethanes 3. Note: Reaction conditions: 3-yne-1,2-diols 1 (0.2 mmol, 1.0 equiv), aurone-derived azadienes 2 (0.2 mmol, 1.0 equiv), JohnPhosAu(MeCN)SbF6 (2 mol%), DCE (2.0 mL), room temperature for 8 h. Isolated yield.
Scheme 2. Substrate scope for forming triarylmethanes 3. Note: Reaction conditions: 3-yne-1,2-diols 1 (0.2 mmol, 1.0 equiv), aurone-derived azadienes 2 (0.2 mmol, 1.0 equiv), JohnPhosAu(MeCN)SbF6 (2 mol%), DCE (2.0 mL), room temperature for 8 h. Isolated yield.
Catalysts 13 01051 sch002
Catalysts 13 01051 sch003 550
Scheme 3. Substrate scope for forming triarylmethanes 5. Note: Reaction conditions: 3-yne-1,2-diols 1 (0.2 mmol, 1.0 equiv) with p-QMs 4 (0.2 mmol), JohnPhosAu(MeCN)SbF6 (2 mol%), DCE (2.0 mL), room temperature for 4 h. Isolated yield.
Scheme 3. Substrate scope for forming triarylmethanes 5. Note: Reaction conditions: 3-yne-1,2-diols 1 (0.2 mmol, 1.0 equiv) with p-QMs 4 (0.2 mmol), JohnPhosAu(MeCN)SbF6 (2 mol%), DCE (2.0 mL), room temperature for 4 h. Isolated yield.
Catalysts 13 01051 sch003
Catalysts 13 01051 g001 550
Figure 1. X-Ray structure of 3k.
Figure 1. X-Ray structure of 3k.
Catalysts 13 01051 g001
Catalysts 13 01051 sch004 550
Scheme 4. Control experiments.
Scheme 4. Control experiments.
Catalysts 13 01051 sch004
Catalysts 13 01051 sch005 550
Scheme 5. Possible reaction mechanism of product 3a.
Scheme 5. Possible reaction mechanism of product 3a.
Catalysts 13 01051 sch005
Table
Table 1. Optimization of the reaction conditions a.
Table 1. Optimization of the reaction conditions a.
Catalysts 13 01051 i001
Entry[Au] (2 mol%)SolventYield (%) b
1JohnPhosAu(MeCN)SbF6DCE85
2IPrAuNTf2DCE60
3AuCl3DCEtrace
4AgNO3DCEtrace
5PbCl2DCEtrace
6CuCl2DCEtrace
7JohnPhosAu(MeCN)SbF6THFtrace
8JohnPhosAu(MeCN)SbF6CH3CNtrace
9JohnPhosAu(MeCN)SbF6toluenetrace
10JohnPhosAu(MeCN)SbF61,4-dioxane55
11JohnPhosAu(MeCN)SbF6DCM60
12-DCENR
a Reaction conditions: reactions run on a 0.2 mmol scale, 1a with 2a in 1:1 mol ratio, Au-catalyst (2 mol%) b Isolated yield, room temperature for 8 h.
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Rao, Q.; Zhang, Y.; Gu, X.-Y.; Liu, Y.-P.; Jiang, B.; Hao, W.-J. A Cascade Synthesis of Unsymmetrical Furanized Triarylmethanes via Gold Self-Relay Catalysis. Catalysts 2023, 13, 1051. https://doi.org/10.3390/catal13071051

AMA Style

Rao Q, Zhang Y, Gu X-Y, Liu Y-P, Jiang B, Hao W-J. A Cascade Synthesis of Unsymmetrical Furanized Triarylmethanes via Gold Self-Relay Catalysis. Catalysts. 2023; 13(7):1051. https://doi.org/10.3390/catal13071051

Chicago/Turabian Style

Rao, Qian, Yan Zhang, Xin-Yu Gu, Yin-Ping Liu, Bo Jiang, and Wen-Juan Hao. 2023. "A Cascade Synthesis of Unsymmetrical Furanized Triarylmethanes via Gold Self-Relay Catalysis" Catalysts 13, no. 7: 1051. https://doi.org/10.3390/catal13071051

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