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Article

Visible-Light-Induced Difunctionalization of the C-C Bond of Alkylidenecyclopropanes with Acyl Chlorides

by
Chuan Ding
†,
Peng-Fei Huang
†,
Biquan Xiong
,
Ke-Wen Tang
* and
Yu Liu
*
Department of Chemistry and Chemical Engineering, Hunan Institute of Science and Technology, Yueyang 414006, China
*
Authors to whom correspondence should be addressed.
†
These authors contributed equally to this work.
Catalysts 2023, 13(6), 919; https://doi.org/10.3390/catal13060919
Submission received: 28 April 2023 / Revised: 15 May 2023 / Accepted: 17 May 2023 / Published: 23 May 2023
(This article belongs to the Special Issue Radical-Mediated Functionalization of Alkenes)
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Abstract

:
A new and powerful visible-light-induced difunctionalization of the C-C σ-bond of alkylidenecyclopropanes via a ring-opening process was developed. Importantly, acyl chlorides are used as both acyl and Cl sources. This strategy provides an effective route for the difunctionalization of the C-C bond with an acyl radical and Cl− to construct a new C-C bond and a C-Cl bond in one pot. In addition, it has a wide range of substrates and can tolerate various functional groups.

1. Introduction

The ring-opening reactions of cyclopropanes provide a powerful and effective strategy to achieve the functionalization of C–C σ-bonds due to their high strain energy [1,2,3,4,5,6]. As an exciting class of cyclopropanes, alkylidenecyclopropanes (ACPs) show high reactivities, and they are widely used in fascinating organic transformations to construct cyclic compounds and functional alkenes [7,8,9,10,11,12]. A typical method for the C-C cleavage of ACPs is the use of transition metals [13,14,15,16,17,18,19] and Lewis or Brønsted acids [20,21,22,23,24] as catalysts. Recently, the development of the oxidative ring opening of ACPs has also afforded an alternative option [25,26,27,28,29,30,31]. For example, in 2021, Shi and co-workers reported a photochemical ring-opening radical clock reaction using innovative NHPI esters bearing alkylidenecyclopropanes for the facile construction of alkynyl derivatives [31].
As simple and readily available building blocks, acyl chlorides have recently received extensive attention [32,33,34,35,36]. One of the most critical transformations is the acylation reaction. Transition-metal-catalyzed acyl reactions using acyl chlorides as acyl sources provide a classical and valuable method for the construction of functional acyl compounds [37,38,39,40,41,42]. In addition, the production of acyl compounds via a radical pathway through the reduction of acyl chlorides is attractive [43,44,45,46,47,48,49]. Due to the importance of acyl compounds, developing a new method to construct such fascinating chemicals is still appealing.
Over the past few decades, difunctionalization has gained much interest because it allows for the introduction of two functional groups into one molecule in one step [50,51,52,53,54]. Among the most common transformations is the difunctionalization of alkenes, which can form two new bonds with a one-step economy. Except for multicomponent reactions, there is no doubt that using one reagent as two different sources offers an exciting pathway to achieve difunctionalization [55,56,57,58,59]. Atom transfer radical addition (ATRA) reactions afford a high-efficiency path to realize the difunctionalization of alkenes and construct a carbon–halo bond (Scheme 1a) [60,61,62,63,64]. In 2022, Liu’s group disclosed a copper-catalyzed asymmetric ATRA reaction and achieved the radical chlorination of acrylamides [64]. Photochemical reactions are regarded as a powerful and green tool in organic synthesis [65,66,67,68,69,70,71,72]. Inspired by our previous work, we herein report a visible-light-induced ATRA reaction for the C-C σ-bond using acyl chlorides as both acyl and Cl sources through a radical addition/SET oxidation/nucleophilic attack and ring-opening process (Scheme 1b).

2. Results and Discussion

In our initiated study, we selected (cyclopropylidenemethylene)dibenzene 1a and benzoyl chloride 2a as model partners to investigate the influence of the reaction conditions (Table 1). The desired difunctionalization product, 3aa, could be produced with a 96% yield under irradiation with a 5 W blue LED light at room temperature for 24 h (entry 1). When the photocatalyst [Ir(ppy)3] was replaced with other photocatalysts, such as [Ru(bpy)3Cl2] and eosin Y, this transformation basically could not occur (entries 2–3). No product was detected in the absence of a photocatalyst or light irradiation, indicating that both were necessary for this reaction (entries 4 and 5). In addition, other light sources showed poorer reactivities (entries 6–8). Both increasing and decreasing the loading of [Ir(ppy)3] led to a slight decrease in the yields (entries 9–10). Next, the effect of the bases was tested, and the results show that NaHCO3 was the most suitable (entries 11–14). In addition, many solvents were explored, and none showed better results than CH3CN (entries 15–19). Increasing the temperature to 50 °C did not increase the yield of 3aa (entry 20). Finally, we were satisfied because the yield of the desired product, 3aa, did not obviously decrease when the reaction expanded to a 1 g scale (entry 21).
After obtaining the optimized reaction conditions, we first tested the reactivities of a series of ACPs in this difunctionalization transformation (Table 2). (Cyclopropylidenemethylene)dibenzene 1a could smoothly react with benzoyl chloride 2a and resulted in the arylation/chlorination product 3aa with a 96% yield. ACPs with electron-donating groups in the para-position of benzene showed greater reactivities than ACPs with electron-withdrawing groups (products 3ba–3ca compared with products 3da–3fa). In addition, (cyclopropylidenemethylene)dibenzene with two methyl groups at the para- and ortho-position of two benzene rings, respectively, could also fit for this transformation (product 3ga). When only one of the benzene rings bore a substitute at the para-position, ACPs were compatible with this difunctionalization reaction and provided a mixture of (Z) and (E)- products 3ha–3ja with good yields (the ratio of Z: E was 1:1, in which 1H NMR decided 3ha and 3ia–3ja were determined by GC-MS).
Then, many acyl chlorides were tested (Table 3). Benzoyl chlorides containing an electron-donating group (such as methoxy and alkyl group) at the para-position were well tolerated for this transformation, while benzoyl chlorides containing an electron-withdrawing group (such as F, Cl, Br, I, CN, and CF3) at the para-position led to a slight decrease in yields (products 3ab–3ak) (X-ray data for 3ad are shown in Supporting Information 5) [73]. Moreover, benzoyl chlorides containing a substituent at the meta- or ortho-position also caused an inevitable decline in yields due to the steric effect (products 3al–3au). Disubstituted benzoyl chlorides were compatible with this visible-light-induced arylation/chlorination of the C-C σ bond and provided the corresponding products in moderate yields (products 3av–3aw). Except for benzoyl chloride derivatives, 2-thiophenecarbonyl chloride also showed great reactivities (product 3ax). What is more, benzoyl bromide was also tolerated and produced the target product 3ay with a 79% yield.
Control experiments were conducted to explore the mechanism of this difunctionalization reaction (Scheme 2). When 3 equiv. radical inhibitor TEMPO or 1,1-diphenylethene was added under the standard conditions, the desired product 3aa was difficult to detect. In addition, the acyl radical trapping product 4 was detected using GC-MS (Scheme 2a), while 5 could be isolated with a 35% yield (Scheme 2b), which proved that a radical pathway was involved in this transformation.
According to the experimental results and reported literature, a probable mechanism is drawn in Scheme 3. Firstly, benzoyl chloride 2a underwent a single electron transfer (SET) with an excited photocatalyst [IrIII*] to produce acyl radical B and chloride anion A. Then, acyl radical B added to (cyclopropylidenemethylene)dibenzene 1a to deliver carbon radical C, which was subsequently oxidated by IrIV to obtain carbon cation D. Then, cation D was nucleophilically attacked by Cl- and the subsequent ring opening of cyclopropyl produced the desired product 3aa.

3. Materials and Methods

3.1. General Information

Commercially available reagents were used throughout without purification unless otherwise stated. The starting alkylidenecyclopropanes (1) [64] were prepared via methods reported in the literature. 1H and 13C NMR spectra were recorded on a Bruker AC-400 instrument (400 MHz for 1H and 100 MHz for 13C) at 20 °C. Chemical shifts (d) are given in ppm downfield from Me4Si and are referenced as the internal standard to the residual solvent (unless indicated) CDCl3 (d = 7.26 for 1H and d = 77.00 for 13C). Coupling constants, J, are reported in hertz (Hz). The following abbreviations were used to explain multiplicities: s = singlet, d = doublet, dd = doublet of doublet, t = triplet, td = triplet of doublet, q = quartet, m = multiplet, and br = broad. Melting points were determined in a capillary tube and are uncorrected. TLC was carried out on SiO2 (silica gel 60 F254), and the spots were located with UV light. Flash chromatography was carried out on SiO2 (silica gel 60, 230–400 mesh ASTM). Drying of organic extracts during work-up of reactions was performed over anhydrous Na2SO4. Evaporation of solvents was accomplished with a Büchi rotatory evaporator. High-resolution mass spectra (HRMS) were obtained on an Agilent mass spectrometer using ESI-TOF (electrospray ionization-time of flight).

3.2. General Procedure for the Synthesis of 3

To a Schlenk tube were added 1 (0.2 mmol), 2 (0.4 mmol, 2 equiv.), CH3CN (2 mL), Ir(ppy)3 (1 mol%), and NaHCO3 (2 equiv.). Then, the mixture was stirred at rt (oil bath temperature) in Ar atmosphere for 24 h until complete consumption of the starting material, as monitored by TLC and GC-MS analysis. After the reaction was finished, the reaction mixture was washed with brine. The aqueous phase was re-extracted with EtOAc (3 × 10 mL). The combined organic extracts were dried over Na2SO4 and concentrated in vacuum. The residue was purified by means of silica gel flash column chromatography (petroleum ether/ethyl acetate = 100:1 to 60:1) to afford the desired product 3.

3.3. Characterization Data for 3

4-Chloro-2-(diphenylmethylene)-1-phenylbutan-1-one (3aa): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (80:1) to afford a white solid with a 96% yield (66.6 mg); mp: 183.0–183.5 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.80–7.78 (m, 2H), 7.43–7.37 (m, 5H), 7.36–7.28 (m, 1H), 7.21–7.17(d, J = 8.0 Hz, 2H), 6.97(s, 5H), 3.65 (t, J = 7.2 Hz, 2H), 3.05 (t, J = 7.2 Hz, 2H). 13C NMR (100 MHz, CDCl3) δ: 200.2, 148.0, 140.9, 140.4, 137.3, 135.1, 132.5, 129.8, 129.3, 129.2, 128.4, 128.0, 127.9, 127.9, 127.7, 42.6, 36.2. HRMS (ESI-TOF) m/z: C23H20ClO (M + H)+ calcd for 347.1197, found 347.1192.
2-(Bis(4-methoxyphenyl)methylene)-4-chloro-1-phenylbutan-1-one (3ba): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (60:1) to afford a white solid with a 97% yield (78.6 mg); mp: 177.3–178.6 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.76 (d, J = 7.6 Hz, 2H), 7.28 (d, J = 8.0 Hz, 3H), 7.17 (s, 2H), 6.91 (t, J = 8.0 Hz, 4H), 6.49 (d, J = 8.0 Hz, 2H), 3.83 (s, 3H), 3.66 (t, J = 6.8 Hz, 2H), 3.60 (s, 3H), 3.06 (t, J = 7.2 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 200.5, 159.2, 159.3, 148.1, 137.7, 134.0, 133.5, 133.0, 132.2, 131.5, 130.8, 129.1, 127.8, 113.6, 113.1, 55.2, 55.0, 42.8, 36.4; HRMS (ESI-TOF) m/z: C25H23ClO3 (M + H)+ calcd for 407.1408, found 407.1403.
4-Chloro-2-(di-p-tolylmethylene)-1-phenylbutan-1-one (3ca): The title compound was prepared according to the general procedure and purified by column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (90:1) to afford a white solid with a 95% yield (72.7mg); mp: 186.6–186.8 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.78 (d, J = 8.0 Hz, 2H), 7.28–7.18 (m, 7H), 6.85 (d, J = 7.2 Hz, 2H), 6.76 (d, J = 7.6 Hz, 2H), 3.63 (t, J = 7.2 Hz, 2H), 3.03 (t, J = 7.2 Hz, 2H), 2.38 (s, 3H), 2.09 (s, 3H); 13C NMR (100 MHz, CDCl3) δ: 200.4, 148.2, 138.3, 137.7, 137.4, 134.2, 132.2, 129.2, 129.8, 129.2, 129.0, 128.4, 127.8, 42.7, 36.3, 21.2, 20.9; HRMS (ESI-TOF) m/z: C25H24ClO (M + H)+ calcd for 375.1510, found 375.1514.
2-(Bis(4-fluorophenyl)methylene)-4-chloro-1-phenylbutan-1-one (3da): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (70:1) to afford a yellow solid with a 91% yield (69.7 mg); mp: 176.3–176.9 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.78 (d, J = 7.6 Hz, 2H), 7.37–7.31 (m, 3H), 7.21 (t, J = 7.6 Hz, 2H), 7.10 (t, J = 8.0 Hz, 2H), 6.94 (t, J = 6.0 Hz, 2H), 6.67 (t, J = 8.4 Hz, 2H), 3.65 (t, J = 6.8 Hz, 2H), 3.04 (t, J = 6.8 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 199.8, 163.4, 163.7, 161.2, 145.8, 132.7, 131.6 (d, J = 82 Hz, 1C), 131.2(d, J = 82 Hz, 1C), 129.1, 128.0, 115.6, 114.9, 114.7, 42.5, 36.1; 19F NMR (376 MHz, CDCl3) δ: 112.9 (d, J = 106.0 Hz, 2F); HRMS (ESI-TOF) m/z: C23H18ClF2O (M + H)+ calcd for 383.1009, found 383.1003.
2-(Bis(4-chlorophenyl)methylene)-4-chloro-1-phenylbutan-1-one (3ea): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (70:1) to afford a yellow solid with an 88% yield (71.6 mg); mp: 169.2–169.9 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.78 (d, J = 7.6 Hz, 2H), 7.40–7.32 (m, 5H), 7.22 (t, J = 7.6 Hz, 2H), 6.96 (d, J = 7.6 Hz, 2H), 6.90 (d, J = 7.6 Hz, 2H), 3.63 (t, J = 6.4 Hz, 2H), 3.02 (t, J = 6.8 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 199.5, 145.1, 139.0, 138.3, 136.9, 136.3, 134.2, 134.1, 132.9, 131.0, 130.8, 129.2, 128.7, 128.1, 42.3, 36.1; HRMS (ESI-TOF) m/z: C23H18Cl3O (M + H)+ calcd for 415.0418, found 415.0415.
2-(Bis(4-bromophenyl)methylene)-4-chloro-1-phenylbutan-1-one (3fa): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (70:1) to afford a yellow solid with an 85% yield (85.3 mg); mp: 189.0–189.5 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.78 (d, J = 7.6 Hz, 2H), 7.54 (d, J = 8.4 Hz, 2H), 7.35 (t, J = 7.2 Hz, 1H), 7.23 (t, J = 8.4 Hz, 4H), 7.11 (d, J = 7.6 Hz, 2H), 6.83 (d, J = 4.0 Hz, 2H), 3.62 (t, J = 8.4 Hz, 2H), 3.02 (d, J = 7.2 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 199.6, 145.2, 136.4, 133.0, 131.8, 131.4, 131.1, 129.3, 128.2, 122.5, 42.4, 36.2; HRMS (ESI-TOF) m/z: C23H18Br2ClO (M + H)+ calcd for 502.9407, found 502.9404.
2-(Bis(2,4-dimethylphenyl)methylene)-4-chloro-1-phenylbutan-1-one (3ga): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (80:1) to afford a yellow liquid with a 92% yield (74.1 mg). 1H NMR (400 MHz, CDCl3) δ: 7.80–7.77 (m, 2H), 7.42–7.34 (m, 3H), 7.30–7.28 (m, 1H), 7.22–6.95 (t, J = 8.8 Hz, 2H), 6.94 (s, 3H), 3.64 (d, J = 7.2 Hz, 2H), 3.01 (d, J = 7.2 Hz, 2H), 2.51 (s, 6H), 2.42 (s, 6H); 13C NMR (100 MHz, CDCl3) δ: 200.2, 148.1, 141.0, 140.4, 137.3, 135.1, 132.5, 129.9, 129.4, 129.3, 128.4, 128.1, 128.0, 127.9, 127.8, 42.7, 36.3, 27.9, 24.3; HRMS (ESI-TOF) m/z: C27H28ClO (M + H)+ calcd for 403.1823, found 403.1821.
4-Chloro-2-((4-fluorophenyl)(4-methoxyphenyl)methylene)-1-phenylbutan-1-one (3ha): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (70:1) to afford a yellow liquid with a 90% yield (71.1 mg). 1H NMR (400 MHz, CDCl3) δ: 7.74 (t, J = 7.2 Hz, 2H), 7.32–7.27 (m, 3H), 7.20 (t, J = 8.0 Hz, 2H), 6.95–6.92 (m, 4H), 6.68–6.64 (m, 2H), 3.08 (s, 3H), 3.66 (t, J = 7.2 Hz, 2H), 3.09 (t, J = 7.2Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 200.3, 163.4, 161.0, 159.5, 147.0, 137.5, 132.6, 132.5, 131.8 (d, J= 8.3 Hz, 1C), 130.8, 129.2, 127.9, 114.8, 114.6, 113.8, 55.2, 42.7, 36.5; 19F NMR (376 MHz, CDCl3) δ: 113.3 (s, 1F); HRMS (ESI-TOF) m/z: C24H21FClO2 (M + H)+ calcd for 395.1209, found 395.1204.
4-Chloro-1-phenyl-2-(phenyl(p-tolyl)methylene)butan-1-one (3ia): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (80:1) to afford a white solid with a 95% yield (68.5 mg); mp: 166.4–166.9 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.79 (t, J = 8.8 Hz, 2H), 7.41–7.35 (m, 3H), 7.30–7.24 (m, 2H), 7.21–7.14 (m, 3H), 6.96–6.94 (m, 2H), 6.86 (d, J = 7.6 Hz, 1H), 6.81 (d, J = 3.2 Hz, 1H), 3.66–3.61 (m, 2H), 3.07–3.01 (m, 2H), 2.37 (s, 1H), 2.08 (s, 1H); 13C NMR (100 MHz, CDCl3) δ: 200.2, 148.2, 148.0, 141.1, 140.5, 137.8, 137.7, 137.5, 137.3, 134.8, 134.4, 132.3, 129.8, 129.8, 129.3, 129.2, 129.0, 128.4, 128.3, 127.8, 127.8, 127.8, 127.6, 42.6, 36.3, 20.9; HRMS (ESI-TOF) m/z: C24H22ClO (M + H)+ calcd for 361.1354, found 361.1356.
4-Chloro-2-((4-chlorophenyl)(phenyl)methylene)-1-phenylbutan-1-one (3ja): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (70:1) to afford a white solid with an 89% yield (67.8 mg); mp: 184.1–184.8 °C (uncorrected).1H NMR (400 MHz, CDCl3) δ: 7.79 (t, J = 8Hz, 2H), 7.43–7.32 (m, 5H), 7.29–7.16 (m, 3H), 6.97–6.90 (m, 4H), 3.66–3.61 (m, 3H), 3.06–3.01 (m, 2H); 13C NMR (100 MHz, CDCl3) δ: 199.8, 146.7, 146.4, 140.5, 139.9, 139.4, 138.7, 137.1, 137.0, 135.7, 135.6, 134.0, 133.9, 132.8, 132.5, 131.0, 130.8, 129.8, 129.3, 129.2, 128.6, 128.5, 128.1, 128.0, 127.9, 127.8, 42.5, 36.1; HRMS (ESI-TOF) m/z: C23H19Cl2O (M + H)+ calcd for 381.0807, found 381.0804.
2-((4-Bromophenyl)(phenyl)methylene)-4-chloro-1-phenylbutan-1-one (3ka): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (70:1) to afford a yellow solid with a 86% yield (73.1 mg); mp: 156.1–156.8 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.81–7.55 (m, 2H), 7.47 (d, J = 4.8 Hz, 1H), 7.39–7.12 (m, 7H), 6.98 (t, J = 2.4 Hz, 2H), 6.97–6.84 (m, 1H), 3.66–3.62 (m, 2H), 3.06–3.01 (m, 2H); 13C NMR (100 MHz, CDCl3) δ: 199.9, 146.7, 146.4, 140.4, 139.8, 139.2, 137.1, 137.0, 135.7, 135.6, 132.8, 132.6, 131.6, 131.3, 131.1, 130.9, 129.8, 129.3, 129.3, 129.2, 128.5, 128.2, 128.1, 127.9, 127.8, 122.2, 42.4, 36.2; HRMS (ESI-TOF) m/z: C23H19ClBrO (M + H)+ calcd for 425.0302, found 425.0301.
4-Chloro-2-(diphenylmethylene)-1-(4-methoxyphenyl)butan-1-one (3ab): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (70:1) to afford a white solid with a 95% yield (71.5 mg); mp: 187.4–187.8 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.82 (d, J = 7.6 Hz, 2H), 7.37 (t, J = 4.4 Hz, 5H), 6.99 (t, J = 7.2 Hz, 5H), 6.69 (d, J = 8.0 Hz, 2H), 3.73 (s, 3H), 3.61 (t, J = 6.8 Hz, 2H), 3.00 (t, J = 6.8 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 198.6, 163.1, 146.4, 140.9, 140.5, 135.1, 131.7, 129.9, 129.6, 129.3, 128.3, 127.8, 127.7, 127.7, 113.2, 55.2, 42.5, 36.3; HRMS (ESI-TOF) m/z: C24H22ClO2 (M + H)+ calcd for 377.1303, found 377.1305.
4-chloro-2-(diphenylmethylene)-1-(p-tolyl)butan-1-one (3ac): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (90:1) to afford a white solid with a 96% yield (69.3 mg); mp: 181.0–182.5 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.72 (d, J = 4.0 Hz, 2H), 7.36 (t, J = 3.6 Hz, 5H), 7.02–6.96 (m, 7H), 3.61 (t, J = 6.8 Hz, 2H), 3.01 (t, J = 6.8 Hz, 2H), 2.24 (m, 3H); 13C NMR (100 MHz, CDCl3) δ: 199.7, 143.3, 146.9, 140.9, 140.4, 135.1, 134.5, 129.7, 129.4, 129.3, 128.6, 128.3, 127.8, 127.7, 127.7, 42.5, 36.3, 21.5; HRMS (ESI-TOF) m/z: C24H22ClO (M + H)+ calcd for 361.1354, found 361.1351.
4-Chloro-2-(diphenylmethylene)-1-(4-fluorophenyl)butan-1-one (3ad): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (80:1) to afford a yellow solid with a 92% yield (67.1 mg); mp: 174.2–174.9 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.82 (d, J = 7.6 Hz, 2H), 7.42–7.37 (m, 7H), 7.35 (t, J = 7.2 Hz, 1H), 7.23 (t, J = 8.4 Hz, 4H), 7.11 (d, J = 7.6 Hz, 2H), 6.83 (d, J = 4.0 Hz, 2H), 3.64 (t, J = 8.4 Hz, 2H), 3.05 (d, J = 7.2 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 198.5, 166.3, 163.8, 148.2, 134.9, 131.9, 131.8, 129.8, 129.3, 128.4, 128.0 (d, J = 79 Hz, 1C), 127.8, 114.8, 42.6, 36.1; 19F NMR (376 MHz, CDCl3) δ: 105.6 (s, 1F); HRMS (ESI-TOF) m/z: C23H19ClFO (M + H)+ calcd for 365.1103, found 365.1107.
4-Chloro-1-(4-chlorophenyl)-2-(diphenylmethylene)butan-1-one (3ae): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (80:1) to afford a white solid with a89% yield (67.8 mg); mp: 172.3–172.9 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.73 (d, J = 8.0 Hz, 2H), 7.74–7.37 (m, 5H), 7.13 (d, J = 8.4 Hz, 2H), 6.98 (s, 5H), 3.63 (t, J = 6.4 Hz, 2H), 3.05 (t, J = 6.8 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 198.8, 148.5, 140.8, 140.1, 138.6, 135.7, 134.7, 130.5, 129.8, 129.3, 128.4, 128.1, 127.8, 42.6, 36.0; HRMS (ESI-TOF) m/z: C23H19Cl2O (M + H)+ calcd for 381.0807, found 381.0805.
1-(4-Bromophenyl)-4-chloro-2-(diphenylmethylene)butan-1-one (3af): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (80:1) to afford a brown solid with a 94% yield (73.1 mg); mp: 175.3–176.5 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.65 (d, J = 8.4 Hz, 2H), 7.42–7.25 (m, 7H), 7.01–6.95 (m, 5H), 3.63 (t, J = 4.0 Hz, 2H), 3.05 (t, J = 4.0 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 199.1, 148.6, 140.8, 140.1, 136.1, 134.7, 131.1, 130.7, 129.8, 129.3, 128.4, 128.2, 128.1, 127.9, 127.4, 42.6, 36.0; HRMS (ESI-TOF) m/z: C23H19ClBrO (M + H)+ calcd for 425.0302, found 425.0305.
4-Chloro-2-(diphenylmethylene)-1-(4-(trifluoromethyl)phenyl)butan-1-one (3ag): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (70:1) to afford a yellow liquid with an 86% yield (71.3 mg). 1H NMR (400 MHz, CDCl3) δ: 7.84 (d, J = 8.0 Hz, 2H), 7.42–7.37 (m, 7H), 6.95 (s, 5H), 3.67 (t, J = 6.8 Hz, 2H), 3.09 (t, J = 6.8 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 199.1, 150.0, 140.8, 140.6, 140.0, 134.8, 130.0, 129.3 (d, J = 18 Hz, 1C), 128.4 (d, J = 22 Hz, 1C), 128.2, 127.9, 124.7 (d, J = 3.8 Hz, 1C), 42.7, 35.6; 19F NMR (376 MHz, CDCl3) δ: 63.2 (s, 3F)HRMS (ESI-TOF) m/z: C24H19ClF3O (M + H)+ calcd for 415.1071, found 415.1070.
4-Chloro-2-(diphenylmethylene)-1-(4-iodophenyl)butan-1-one (3ah): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (70:1) to afford a white liquid with an 83% yield (78.5 mg). 1H NMR (400 MHz, CDCl3) δ: 7.55–7.48 (m, 4H), 7.40–7.35 (m, 5H), 7.01–6.94 (m, 5H), 3.63 (t, J = 6.8 Hz, 2H), 3.054 (t, J = 6.8 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 199.4, 148.6, 140.8, 140.1, 137.1, 136.7, 134.7, 130.6, 129.8, 129.3, 128.4, 128.2, 128.1, 127.9, 100.4, 42.6, 36.09; HRMS (ESI-TOF) m/z: C23H19ClIO (M + H)+ calcd for 473.0164, found 473.0161.
4-Chloro-2-(diphenylmethylene)-1-(4-ethylphenyl)butan-1-one (3ai): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (80:1) to afford a white solid with a 95% yield (71.2 mg); mp: 176.3–176.9 °C (uncorrected)1H NMR (400 MHz, CDCl3) δ: 7.74–7.72 (m, 2H), 7.42–7.35 (m, 5H), 7.03–6.96 (m, 7H), 3.62 (t, J = 7.2 Hz, 2H), 3.021 (t, J = 7.2 Hz, 2H), 2.58–2.52 (m, 2H), 1.14 (t, J = 7.6 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ: 199.8, 149.5, 147.1, 140.9, 140.5, 135.2, 134.8, 129.7, 129.5, 129.3, 128.4, 127.8, 127.7, 127.4, 42.6, 36.3, 28.82, 14.95; HRMS (ESI-TOF) m/z: C25H24ClO (M + H)+ calcd for 375.1510, found 375.1513.
4-(4-Chloro-2-(diphenylmethylene)butanoyl)benzonitrile (3aj): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (60:1) to afford a white solid with an 86% yield (63.9 mg); mp: 195.3–195.8 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.81–7.94 (m, 2H), 7.44–7.37 (m, 7H), 7.00–6.90 (m, 5H), 3.68 (t, J = 6.8 Hz, 2H), 3.11 (t, J = 6.8 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 198.7, 150.9, 141.2, 140.8, 139.9, 134.7, 131.6, 130.1, 129.3, 128.7, 128.5, 128.4, 128.0, 118.1, 114.9, 42.8, 35.8; HRMS (ESI-TOF) m/z: C24H19ClNO (M + H)+ calcd for 372.1150, found 372.1158.
1-(4-(Tert-butyl)phenyl)-4-chloro-2-(diphenylmethylene)butan-1-one (3ak): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (80:1) to afford a white liquid with an 86% yield (69.3 mg). 1H NMR (400 MHz, CDCl3) δ: 7.72 (d, J = 8.4 Hz, 2H), 7.42–7.34 (m, 5H), 7.21 (d, J = 8.2 Hz, 2H), 7.00–6.93 (m, 5H), 3.63 (t, J = 7.2 Hz, 2H), 3.02 (t, J = 6.8 Hz, 2H), 1.22 (s, 9H); 13C NMR (100 MHz, CDCl3) δ: 199.8, 156.0, 147.3, 140.9, 140.4, 135.3, 134.5, 129.7, 129.3, 129.3, 128.4, 127.8, 127.7, 124.8, 42.6, 36.2, 34.9, 30.8; HRMS (ESI-TOF) m/z: C27H28ClO (M + H)+ calcd for 403.1823, found 403.1828.
4-Chloro-2-(diphenylmethylene)-1-(2-methoxyphenyl)butan-1-one (3al): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (70:1) to afford a white solid with an 86% yield (64.8 mg); mp: 177.1–177.9 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.39–7.32 (m, 4H), 7.28–7.25 (m, 2H), 7.15 (t, J = 4.0 Hz, 1H), 6.96 (t, J = 3.6 Hz, 3H), 6.90 (d, J = 3.2 Hz, 2H), 6.70 (t, J = 7.6 Hz, 1H), 6.62–6.60 (m, 1H), 3.84 (s, 3H), 3.73 (t, J = 7.6 Hz, 2H), 3.03 (t, J = 7.6 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 199.3, 157.3, 148.2, 141.1, 140.8, 137.6, 132.6, 130.7, 129.5, 129.3, 129.0, 128.3, 127.8, 127.5, 127.4, 119.9, 110.6, 55.3, 43.0, 36.0; HRMS (ESI-TOF) m/z: C24H22ClO2 (M + H)+ calcd for 377.1303, found 377.1306.
4-Chloro-2-(diphenylmethylene)-1-(o-tolyl)butan-1-one (3am): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (80:1) to afford a white solid with an 83% yield (59.9 mg); mp: 173.0–173.5 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 8.05 (t, J = 7.6Hz, 1H), 7.70 (d, J = 1.6 Hz, 1H), 7.50 (t, J = 1.6 Hz, 1H), 7.43–7.19 (m, 5H), 7.09–6.87 (m, 4H), 3.73 (t, J = 7.0 Hz, 1H), 3.08 (t, J = 7.0 Hz, 1H), 2.70 (s, 3H), 2.40 (s, 2H); 13C NMR (100 MHz, CDCl3) δ: 201.4, 162.8, 150.2, 142.5, 141.5, 140.5, 138.6, 138.3, 137.0, 133.5, 132.1, 131.3, 131.1, 130.9, 129.9, 129.3, 129.1, 128.3, 128.0, 127.7, 127.6, 127.5, 126.0, 124.8, 42.84, 35.87, 21.98; HRMS (ESI-TOF) m/z: C24H22ClO (M + H)+ calcd for 361.1354, found 361.1351.
4-Chloro-2-(diphenylmethylene)-1-(2-fluorophenyl)butan-1-one (3an): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate 70:1) to afford a yellow solid with an 80% yield (58.2 mg); mp: 168.2–168.5 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.49–7.40 (m, 1H), 7.38–7.30 (m, 3H), 7.29 (d, J = 7.2 Hz, 2H), 7.18–7.13 (m, 1H), 6.96 (s, 5H), 6.88 (t, J = 7.6 Hz, 1H), 6.75 (t, J = 9.2 Hz, 1H), 3.73 (t, J = 7.6 Hz, 2H), 3.05 (t, J = 7.6 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 196.8, 161.3, 158.8, 150.0 (d, J = 23Hz, 1C), 130.7, 129.7, 129.0, 128.3, 128.1, 128.1, 127.7, 123.6, 123.5, 115.9, 115.6, 42.8, 36.0; 19F NMR (376 MHz, CDCl3) δ: 111.0 (t, J = 4.8 Hz, 1F); HRMS (ESI-TOF) m/z: C23H19ClFO (M + H)+ calcd for 365.1103, found 365.1109.
1-(2-bromophenyl)-4-chloro-2-(diphenylmethylene)butan-1-one (3ao): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (80:1) to afford a white solid with a 76% yield (64.4 mg); mp: 177.2–177.9 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.44–7.25 (m, 7H), 7.05–6.89 (m, 7H), 3.79 (t, J = 7.2 Hz, 2H), 3.11 (t, J = 7.2 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 198.7, 153.1, 141.2, 140.6, 140.4, 135.6, 133.4, 131.1, 130.9, 129.6, 129.0, 128.3, 128.2, 128.1, 127.8, 126.4, 120.8, 43.0, 35.8; HRMS (ESI-TOF) m/z: C23H19BrClO (M + H)+ calcd for 425.0302, found 425.0307.
4-Chloro-1-(2-chlorophenyl)-2-(diphenylmethylene)butan-1-one (3ap): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (80:1) to afford a white solid with a 78% yield (59.4 mg); mp: 176.1–176.8 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.42–7.35 (m, 4H), 7.32–7.29 (m, 2H), 7.05–6.96 (m, 6H), 6.92–6.89 (m, 2H), 3.78 (t, J = 7.2 Hz, 2H), 3.10 (t, J = 7.2 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 198.4, 152.6, 141.1, 140.5, 138.9, 136.0, 131.9, 131.1, 130.7, 130.0, 129.6, 129.0, 128.3, 128.2, 128.1, 127.8, 125.9, 43.0, 35.8; HRMS (ESI-TOF) m/z: C23H19Cl2O (M + H)+ calcd for 381.0807, found 381.0808.
4-Chloro-2-(diphenylmethylene)-1-(3-methoxyphenyl)butan-1-one (3aq): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (70:1) to afford a white solid with a 90% yield (67.8 mg); mp: 186.6–186.9 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.42–7.33 (m, 7H), 7.09 (t, J = 8.0 Hz, 1H), 6.99 (s, 5H), 6.86–6.84 (m, 1H), 3.75 (s, 3H), 3.64 (t, J = 7.2 Hz, 2H), 3.04 (t, J = 7.2 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 199.9, 159.0, 147.9, 140.9, 140.3, 138.6, 135.1, 129.8, 129.3, 128.9, 128.4, 127.9, 127.9, 127.7, 122.2, 119.3, 113.1, 55.2, 42.6, 36.2; HRMS (ESI-TOF) m/z: C24H22ClO2 (M + H)+ calcd for 377.1303, found 377.1305.
4-Chloro-2-(diphenylmethylene)-1-(m-tolyl)butan-1-one (3ar): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (80:1) to afford a white solid with a 92% yield (66.4 mg); mp: 174.3–174.9 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.59 (d, J = 6.0, 2H), 7.42–7.24 (m, 5H), 7.12–7.05 (m, 2H), 6.98 (m, 5H), 3.63 (t, J = 6.8 Hz, 2H), 3.02 (t, J = 7.2 Hz, 2H), 2.25 (m, 3H); 13C NMR (100 MHz, CDCl3) δ: 200.2, 147.6, 141.0, 140.4, 137.5, 137.1, 135.2, 133.3, 129.8, 129.7, 129.3, 128.4, 127.9, 127.8, 127.8, 127.7, 126.6, 42.6, 36.2, 21.1; HRMS (ESI-TOF) m/z: C24H22ClO (M + H)+ calcd for 361.1354, found 361.1355.
4-Chloro-2-(diphenylmethylene)-1-(3-fluorophenyl)butan-1-one (3as): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (70:1) to afford a yellow liquid with an 87% yield (63.5 mg). 1H NMR (400 MHz, CDCl3) δ: 7.57–7.55 (m, 1H), 7.45–7.36 (m, 6H), 7.15 (t, J = 5.6 Hz, 1H), 7.14–6.94 (m, 6H), 3.65 (t, J = 7.2 Hz, 2H), 3.06 (t, J = 7.2 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 198.9, 163.3, 160.8, 149.2, 140.8, 140.1, 139.7, 139.6, 134.8, 129.9, 129.4 (d, J= 7.6 Hz, 1C), 129.3, 128.4 (1C), 127.9, 125.0, 119.3, 119.1, 115.8, 115.6, 42.6, 36.0; 19F NMR (376 MHz, CDCl3) δ: 112.9 (s, 1F); HRMS (ESI-TOF) m/z: C23H19ClFO (M + H)+ calcd for 365.1103, found 365.1105.
4-Chloro-1-(3-chlorophenyl)-2-(diphenylmethylene)butan-1-one (3at): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (80:1) to afford a white solid with an 84% yield (64.0 mg); mp: 174.1–174.5 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.71 (t, J = 1.6 Hz, 1H), 7.64 (d, J = 7.6 Hz, 1H), 7.41–7.21 (m, 1H), 7.09 (t, J = 8.0 Hz, 1H), 7.00-6.95 (m, 5H), 3.65 (t, J = 6.8 Hz, 2H), 3.06 (t, J = 6.8 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 198.7, 149.4, 140.9, 140.1, 139.0, 133.9, 134.7, 132.1, 129.9, 129.3, 129.2, 123.1, 128.4, 128.2, 128.1, 127.9, 127.3, 42.6, 36.0; HRMS (ESI-TOF) m/z: C23H19Cl2O (M + H)+ calcd for 381.0807, found 381.0802.
1-(3-Bromophenyl)-4-chloro-2-(diphenylmethylene)butan-1-one (3au): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (70:1) to afford a white solid with an 81% yield (68.8 mg); mp: 168.2–168.8 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.87 (t, J = 1.6 Hz, 1H), 7.69–7.67 (m, 1H), 7.43–7.36 (m, 6H), 7.05–6.94 (m, 6H), 3.65 (t, J = 6.8 Hz, 2H), 3.06 (t, J = 6.8 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 198.6, 149.5, 140.8, 140.1, 139.2, 134.9, 134.6, 132.2, 129.8, 129.3, 129.3, 128.4, 128.2, 128.1, 127.9, 127.7, 122.0, 42.6, 36.0; HRMS (ESI-TOF) m/z: C23H19BrClO (M + H)+ calcd for 425.0302, found 425.0300.
4-Chloro-1-(3,4-dimethoxyphenyl)-2-(diphenylmethylene)butan-1-one (3av): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (60:1) to afford a white solid with a 94% yield (76.5 mg); mp: 198.1–199.4 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.53–7.50 (m, 1H), 7.43–7.33 (m, 6H), 7.03–6.98 (m, 5H), 6.66 (m 1H), 3.85 (s, 3H), 3.83 (s, 3H), 3.62 (t, J = 7.0 Hz, 2H), 3.01 (t, J = 7.0 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 198.7, 152.9, 148.3, 135.0, 130.0, 129.6, 129.3, 128.4, 127.8, 127.8, 124.7, 111.1, 109.6, 55.8, 55.7, 42.6, 36.3; HRMS (ESI-TOF) m/z: C25H24ClO3 (M + H)+ calcd for 407.1408, found 407.1405.
4-Chloro-1-(3,5-dichlorophenyl)-2-(diphenylmethylene)butan-1-one (3aw): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (70:1) to afford a white liquid with an 82% yield (68.0 mg). 1H NMR (400 MHz, CDCl3) δ: 7.56 (d, J = 1.6 Hz, 2H), 7.43–7.36 (m, 5H), 7.21 (t, J = 2.0 Hz, 1H), 7.04 (t, J = 3.6Hz, 3H), 6.96–6.93 (m, 2H), 3.66 (t, J = 6.8 Hz, 2H), 3.08 (t, J = 6.8 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 197.3, 150.8, 140.8, 140.0, 139.9, 134.5, 134.4, 131.5, 129.9, 129.3, 128.6, 128.5, 128.4, 128.0, 127.5, 42.7, 35.8; HRMS (ESI-TOF) m/z: C23H18Cl3O (M + H)+ calcd for 415.0418, found 415.0417.
4-Chloro-2-(diphenylmethylene)-1-(thiophen-2-yl)butan-1-one (3ax): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (70:1) to afford a yellow liquid with an 84% yield (64.1 mg). 1H NMR (400 MHz, CDCl3) δ: 7.52–7.42 (m, 1H), 7.42–7.39 (m, 3H), 7.37–7.34 (m, 3H), 7.08–7.04 (m 5H), 6.83–6.81 (m, 1H), 3.63 (t, J = 7.2 Hz, 2H), 2.99 (t, J = 6.8 Hz, 2H); 13C NMR (100 MHz, CDCl3) δ: 192.2, 147.1, 144.1, 141.0, 135.4, 140.2, 134.4, 134.2, 129.7, 129.3, 128.4, 127.9, 127.9, 127.5, 42.4, 36.1; HRMS (ESI-TOF) m/z: C21H18ClOS (M + H)+ calcd for 353.0761, found 353.0763.
4-Bromo-2-(diphenylmethylene)-1-phenylbutan-1-one (3ay): The title compound was prepared according to the general procedure and purified by means of column chromatography on silica gel and eluted with petroleum ether/ethyl acetate (80:1) to afford a white solid with a 79% yield (64.1 mg); mp: 188.1–188.6 °C (uncorrected). 1H NMR (400 MHz, CDCl3) δ: 7.80–7.77 (m, 2H), 7.43–7.36 (m, 5H), 7.31–7.25 (m, 1H), 7.21–7.17 (m, 2H), 6.97 (s, 5H), 3.67–3.63 (m, 2H), 3.06–3.04 (m, 2H); 13C NMR (100 MHz, CDCl3) δ: 200.2, 148.0, 140.9, 140.4, 137.3, 135.1, 132.5, 129.8, 129.3, 129.2, 128.4, 128.0, 127.9, 127.9, 127.7, 42.6, 36.2. HRMS (ESI-TOF) m/z: C23H20BrO (M + H)+ calcd for 391.0692, found 391.0696.

4. Conclusions

In conclusion, we have developed a new and effective method for the difunctionalization of C-C σ bonds via a visible-light-induced ATRA reaction. Acyl chlorides served as both acyl and Cl sources in this transformation. A lot of fully substituted alkenes were produced with good yields under room temperature. The preliminary mechanism study indicated that a radical process was involved in this reaction.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/catal13060919/s1, copies of NMR spectra and X-ray data for 3ad (CCDC2262739). Crystal structure of 3ad.

Author Contributions

Conceptualization, Y.L.; investigation, C.D.; data curation, B.X.; writing—original draft preparation, P.-F.H.; writing—review and editing, K.-W.T.; supervision, Y.L. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by National Natural Science Foundation of China (No. 22078084 and 51874132), Scientific Research Fund of Hunan Provincial Education Department (No. 20A224, 21A0399 and 22B0674), and Science and Technology Planning Project of Hunan Province (No. 2020RC3056).

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.

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Catalysts 13 00919 sch001 550
Scheme 1. ATRA reactions for difunctionalization.
Scheme 1. ATRA reactions for difunctionalization.
Catalysts 13 00919 sch001
Catalysts 13 00919 sch002 550
Scheme 2. Control Experiments.
Scheme 2. Control Experiments.
Catalysts 13 00919 sch002
Catalysts 13 00919 sch003 550
Scheme 3. Possible mechanisms.
Scheme 3. Possible mechanisms.
Catalysts 13 00919 sch003
Table
Table 1. Screening optimal conditions1.
Table 1. Screening optimal conditions1.
Catalysts 13 00919 i001
EntryVariation from the Standard ConditionsYield (%) 2
1None96
2 3[Ru(bpy)3Cl2] instead of [Ir(ppy)3]9
3 3Eosin Y instead of [Ir(ppy)3]0
4 3Without [Ir(ppy)3]0
5 3Without additional light0
6 4None68
7 5None91
8 6None86
9[Ir(ppy)3] (2 mol %)95
10[Ir(ppy)3] (0.5 mol %)88
11Na2CO3 instead of NaHCO375
12K2CO3 instead of NaHCO368
13Et3N instead of NaHCO324
142,6-Lutidine instead of NaHCO375
15Toluene instead of CH3CN87
16EtOAc instead of CH3CN90
17THF instead of CH3CN85
18 3DMF instead of CH3CN<5
19 3DMSO instead of CH3CN<5
20At 50 °C90
21 7None86
1 Reaction conditions: 1a (0.2 mmol), 2a (0.4 mmol, 2 equiv.), [Ir(ppy)3] (1 mol %), NaHCO3 (0.4 mmol, 2 equiv.), CH3CN (2 mL), rt, argon, 5 W blue LED light, and 24 h. 2 Isolated yields. 3 Most of the starting materials were recovered. 4 A 3 W blue LED light instead of a 5 W blue LED light. 5 A 12 W blue LED light instead of a 5 W blue LED light. 6 A 36 W compact fluorescent light instead of a 5 W blue LED light. 7 1a (1.0 g, 4.85 mmol), 2a (9.7 mmol, 2 equiv.), [Ir(ppy)3] (1 mol %), NaHCO3 (9.7 mmol, 2 equiv.), CH3CN (5 mL), rt, argon, a 5 W blue LED light, and 72 h.
Table
Table 2. Scope of ACPs (1) 1.
Table 2. Scope of ACPs (1) 1.
Catalysts 13 00919 i002
Catalysts 13 00919 i003
1 Reaction conditions: 1 (0.2 mmol), 2a (0.4 mmol, 2 equiv.), [Ir(ppy)3] (1 mol %), NaHCO3 (0.4 mmol, 2 equiv.), CH3CN (2 mL), rt, argon, a 5 W blue LED light and 24 h.
Table
Table 3. Scope of acyl chlorides (2) 1.
Table 3. Scope of acyl chlorides (2) 1.
Catalysts 13 00919 i004
Catalysts 13 00919 i005
1 Reaction conditions: 1a (0.2 mmol), 2 (0.4 mmol, 2 equiv.), [Ir(ppy)3] (1 mol %), NaHCO3 (0.4 mmol, 2 equiv.), CH3CN (2 mL), rt, argon, a 5 W blue LED light and 24 h. 2 The starting material was benzoyl bromide.
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MDPI and ACS Style

Ding, C.; Huang, P.-F.; Xiong, B.; Tang, K.-W.; Liu, Y. Visible-Light-Induced Difunctionalization of the C-C Bond of Alkylidenecyclopropanes with Acyl Chlorides. Catalysts 2023, 13, 919. https://doi.org/10.3390/catal13060919

AMA Style

Ding C, Huang P-F, Xiong B, Tang K-W, Liu Y. Visible-Light-Induced Difunctionalization of the C-C Bond of Alkylidenecyclopropanes with Acyl Chlorides. Catalysts. 2023; 13(6):919. https://doi.org/10.3390/catal13060919

Chicago/Turabian Style

Ding, Chuan, Peng-Fei Huang, Biquan Xiong, Ke-Wen Tang, and Yu Liu. 2023. "Visible-Light-Induced Difunctionalization of the C-C Bond of Alkylidenecyclopropanes with Acyl Chlorides" Catalysts 13, no. 6: 919. https://doi.org/10.3390/catal13060919

APA Style

Ding, C., Huang, P. -F., Xiong, B., Tang, K. -W., & Liu, Y. (2023). Visible-Light-Induced Difunctionalization of the C-C Bond of Alkylidenecyclopropanes with Acyl Chlorides. Catalysts, 13(6), 919. https://doi.org/10.3390/catal13060919

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