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Article

Photoredox-Catalyzed Synthesis of 3-Sulfonylated Pyrrolin-2-ones via a Regioselective Tandem Sulfonylation Cyclization of 1,5-Dienes

by
Ran Ding
1,*,
Liang Li
1,
Ya-Ting Yu
1,
Bing Zhang
1 and
Pei-Long Wang
2,3,*
1
College of Chemistry and Materials Engineering, Anhui Science and Technology University, Bengbu 233100, China
2
Key Laboratory of Green and Precise Synthetic Chemistry and Applications, Ministry of Education, School of Chemistry and Materials Science, Huaibei Normal University, Huaibei 235000, China
3
Information College, Huaibei Normal University, Huaibei 235000, China
*
Authors to whom correspondence should be addressed.
Molecules 2023, 28(14), 5473; https://doi.org/10.3390/molecules28145473
Submission received: 24 May 2023 / Revised: 9 July 2023 / Accepted: 10 July 2023 / Published: 17 July 2023
(This article belongs to the Special Issue Photocatalytic Materials and Photocatalytic Reactions)
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Versions Notes

Abstract

:
A mild, visible-light-induced, regioselective cascade sulfonylation-cyclization of 1,5-dienes with sulfonyl chlorides through the intermolecular radical addition/cyclization of alkenes C(sp2)-H was developed. This procedure proceeds well and affords a mild and efficient route to a range of monosulfonylated pyrrolin-2-ones at room temperatures.

1. Introduction

Pyrrolin-2-ones, which constitute one of the most prominent classes of skeletons exhibiting unique biological activities, are prevalent in a large number of biological pharmaceutical molecules [1,2] and natural products, like chaetogline, violacein, and hypomycine [3,4,5,6] (Figure 1). In this context, considerable effort has been focused in establishing such valuable frameworks, but most of these methods suffer from transition metals or harsh reaction conditions [7,8,9,10,11,12]. Therefore, developing general and effective synthetic methods for pyrrolin-2-ones and its derivatives with mild conditions has been attracting increasing attention and largely promote progress in this area [13,14,15,16,17,18]. On the other hand, the photoinduced radical cascade cyclization reaction has become a powerful tool to construct N-containing heterocycles because of its extremely high efficiency, inherently green, infinite availability, safety, and ease of operation [19,20,21,22,23,24]. However, such an efficient strategy for the synthesis of pyrrolin-2-ones has rarely been reported [25].
Sulfones constitute an important class of functional groups in organic synthesis that can participate in various chemical transformations [26,27] and that are found widely in the structures of natural products [28,29,30]. The introduction of sulfonyl functional groups can cause molecules to exhibit unique biological activity [31,32]. In this regard, a considerable amount of effort has been devoted to the development of efficient, simple, and convenient methods for synthesizing sulfonyl-containing compounds [33,34,35,36,37,38]. Among the many approaches, the difunctionalization of alkenes through a radical process has been used to prepare several sulfone-containing compounds [39,40,41,42,43,44,45,46,47,48]. Sulfonyl chloride is a readily available and easily handled source of the sulfonyl moiety and is commonly used to generate sulfonyl radicals under visible light conditions; major advances have focused on reactions with heteroaryl or aryl-tethered alkenes to produce sulfonyl-containing aromatic compounds (Scheme 1a) [49,50,51,52,53,54,55]. Nevertheless, the reactions of vinyl-tethered alkenes remain elusive [56,57].
Considering the significance of pyrrolinones and the importance of sulfone moieties in organic synthesis. Herein, we aimed to develop an unprecedented visible-light-induced photoredox-catalyzed reaction of linear 1,5-dienes with sulfonyl chlorides via regioselective sulfonylation and 5-endo cyclization to produce important pyrrolinones (Scheme 1b). However, three challenges hinder the successful development of such a process: (i) The selective addition of the sulfone radical between two carbon-carbon double bonds is challenging. (ii) 6-Exo cyclization competes with the desired reaction and needs to be restricted. (iii) The C=C bond in the target product continues to react with the sulfonyl radical to afford 3,4-disulfonated pyrrolin-2-ones.
We then focused on the reaction of N-acetyl-N-(1-phenylvinyl)methacrylamide 1a and p-toluenesulfonyl chloride 2a. To our delight, when the reaction was performed in the presence of a catalytic amount of fac-Ir(ppy)3 and equivalent of Na2CO3 in CH2Cl2 under irradiation with 20 W white LEDs (Light-Emitting Diodes) for 16 h, the target sulfonylated pyrrolinone 3a could be isolated in 57% yield (Table 1, entry 1). Subsequently, other photocatalysts, such as Ru(bpy)3Cl2 and eosin Y, were investigated, but all failed to obtain product 3a (entries 2, 3). After examining various bases, such as Li2CO3 (59%), NaHCO3 (64%), K3PO4 (72%), and Na3PO4 (63%), K3PO4 was determined to be the best base (entries 4–8). A variety of solvents, including DCE (1,2-dichloroethane), CHCl3, acetone, toluene, THF (tetrahydrofuran), and EtOAc, were subsequently screened, but the yield of product 3a was not promoted (entries 9–14). Next, the amounts of K3PO4 were evaluated (entries 15, 16). Using 1.5 equiv. of K3PO4 improved the yield of product 3a by 79%. When the light source was changed to 5 W white LEDs, product 3a was afforded in the same yield as previously obtained (entries 15 vs. 17). The results of the control experiments showed that visible light, photocatalyst [fac-Ir(ppy)3], and base K3PO4 were necessary for this reaction (entries 18–20).

2. Results and Discussion

After obtaining the optimal reaction conditions, we embarked upon exploring the substrate scope of 1,5-dienes. Different R1, R2, R3 and R4 groups of 1,5-dienes were tested with p-toluenesulfonyl chloride 2a; the results are shown in Figure 2. Substrates with halogen atoms (F, Cl, Br, and I) and electron-donating groups (Me and MeO) at the para-positions of the benzene ring proceeded well to give target products 3b–3g and 3g–3h in medium to good yields. Gratifyingly, the CO2Et group at the para-position of the benzene ring furnished product 3f in an acceptable yield. The reactivity of substituents at the meta- or ortho-position was also tested, achieving yields of products 3i–3l from 46% to 82%. Notably, substrates with an ethyl group at the β-position of the enamide moiety or an n-butyl group at the α-position of the acrylamide moiety smoothly converted to the corresponding product 3m or 3n in 85% yield or 62% yield. In addition, using propionyl or isobutyryl as the nitrogen-protecting groups was viable for this reaction to give target products 3o and 3p in considerable yields.
Next, we moved on to explore the generality of various sulfonyl chlorides (Figure 3). Arylsulfonyl chlorides bearing electron-rich (Me, MeO, and t-Bu) groups at different positions worked well, giving corresponding sulfones 4b–4e in 66–84% yield. Electron-poor arylsulfonyl chlorides, such as Br, I, CN, CF3, and NO2 groups on the benzene ring, allowed the formation of product 4f–4j in 41% to 78% yield with the need for 20 W white LEDs as the light source. It is noteworthy that arylsulfonyl chlorides having substituents at the ortho-position were inferior to those at the para- or meta-position, mainly because of the large steric hindrance of the ortho-position (4b vs. 4e and 4k vs. 4l). Remarkably, 2-thiophenesulfonyl chloride survived under the current conditions to achieve product 4m in 62% yield. Moreover, alkyl-substituted sulfonyl chlorides, such as cyclopropyl and ethyl, were applicable for this reaction and transferred to 4n and 4o in 68% and 62% yield, respectively.
In order to further expand the practicality of the reaction, a gram scale reaction and removal of OAc group of compound 4a were conducted. We were delighted to obtain the sulfonylated pyrrolinone 4a in 78% yield with a prolonged time when the reaction was taken on 1 mmol scale (Scheme 2, (1)). Furthermore, with the addition of n-BuLi in THF at −78 °C, the compound 4a could smoothly remove the OAc group, which generated the product 4aa in 84% yield (Scheme 2, (2)).
To shed the possible mechanism of this visible-light-induced sulfonylation-cyclization of 1,5-dienes, some control experiments were carried out (Scheme 3). When 2.0 equivalents of TEMPO or 1,1-diphenylethylene was added to the reaction of 1,5-diene and p-toluenesulfonyl chloride under standard conditions, the transformation was completely suppressed, suggesting that a free-radical pathway may be involved in this sulfonylation-cyclization reaction. In addition, visible-light irradiation on/off experiments were performed on the model reaction, and the results show that a long-chain process was unlikely to be involved in this reaction (see Supplementary Materials).
According to the above experimental results and previous literature reports [13,14,15,16,17,18], we propose a possible mechanism for visible-light-induced regioselective cascade sulfonylation-cyclization of 1,5-dienes (Scheme 4). First, the photocatalyst [fac-Ir(ppy)3] under visible light irradiation is excited to form the strongly reducing state *[fac-Ir(ppy)3]. A single electron transfer between *[fac-Ir(ppy)3] and p-toluenesulfonyl chloride produces the p-toluenesulfonyl radical and oxidation state [fac-Ir(ppy)3]+. Second, the p-toluenesulfonyl radical was selectively added to the terminal carbon-carbon double bond of acrylamide of 1,5-diene, followed by a 5-endo cyclization to produce radical species II [58,59]. Although 5-endo cyclizations are often less favorable kinetically than their 4-exo cyclizations, the switch from 4-exo to 5-endo mode can be achieved through specific properties of the Ts radical [60,61]. The high regioselectivity can be explained by the reason that the rate of sulfonyl radical addition to the carbo–carbon double bond of acrylamide is much greater than to the enamine carbon–carbon double bond. Third, radical species II loses an electron by the oxidation of photocatalyst [fac-Ir(ppy)3]+ to forge tertiary cation intermediate III and to regenerate photocatalyst [fac-Ir(ppy)3] for the next turnover. Last, deprotonation of cation intermediate III occurs in the presence of K3PO4, giving sulfonylated pyrrolinone 3a. However, since the presence of base is important for the reaction, it cannot be ruled out that the radical II is directly deprotonated by the base to form radical anion, which is oxidized by the photocatalyst [fac-Ir (ppy)3]+ [62]. It is notable that arylsulfonyl radicals are prone to loss of SO2 to form aryl radicals, which could induce the cyclization of 1,5-dienes in the same way as arylsulfonyl radicals, but the corresponding products have not been found in this system [63,64,65,66,67,68].

3. Materials and Methods

3.1. General Considerations

All the reagents purchased from Leyan company were directly used. 1H-NMR and 13C-NMR spectra of the products were recorded on a Bruker FT-NMR 400M or 600M spectrometer (Bruker Beijing Scientific Technology Co., Ltd., Beijing, China). Chemical shifts spectra are given as δ in the units of parts per million (ppm) with reference to tetramethylsilane (TMS). Multiplicities were indicated as follows: d (doublet); s (singlet); t (triplet); q (quartet); m (multiplets); etc. Coupling constants are reported as a J value in Hz. High-resolution mass spectral analysis (HRMS) of the products were collected on an Agilent Technologies 6540 UHD Accurate-Mass Q-TOF LC/MS (ESI) instrument (Beijing Agilent Technologies Co., Ltd, Beijing, China).

3.2. Typical Procedure for the Preparation of 3a

1,5-dienes 1a (0.1 mmol), sulfonyl chlorides 2a (0.2 mmol), fac-Ir(ppy)3 (1 mol%), K3PO4 (1.5 equiv.), and CH2Cl2 (1 mL) were added into a dry 25 mL Schlenk tube containing a magnetic stirring bar under nitrogen atmosphere, Then the mixture was stirred and irradiated with 5 W white LEDs at room temperature for 16 h. After completing, the reaction mixture was directly subjected to flash column chromatography (10–40% EtOAc/Petroleum ether) to obtain the desired product 3a as a white solid (79% yield).

3.3. Procedure for the Synthesis of the Coupling Product 4aa

n-BuLi (2.5 M, 0.24 mmol) was slowly added to the solution of compound 4a (0.2 mmol) and THF (8 mL) at −78 °C. After 15 min, the reaction increased to room temperature. After completing, 8 mL water was added to quench the reaction and the mixture was extracted with 10 mL dichloromethane 3 times. The combined dichloromethane phases were dried over CaCl2, concentrated in vacuo and purified by flash column chromatography (30–40% EtOAc/petroleum ether) to furnish the desired product 4aa as a white solid (84% yield).
1-Acetyl-3-methyl-5-phenyl-3-(tosylmethyl)-1H-pyrrol-2(3H)-one (3a): 1H NMR (600 MHz, CDCl3) δ 7.71 (d, J = 8.3 Hz, 2H), 7.37–7.34 (m, 3H), 7.27 (d, J = 8.1 Hz, 2H), 7.24 (dd, J = 6.6, 3.0 Hz, 2H), 5.51 (s, 1H), 3.69 (d, J = 14.4 Hz, 1H), 3.46 (d, J = 14.4 Hz, 1H), 2.49 (s, 3H), 2.42 (s, 3H), 1.39 (s, 3H). δ 13C NMR (151 MHz, CDCl3) δ 179.60, 169.23, 145.06, 142.87, 136.57, 129.89, 128.50, 128.21, 127.88, 126.78, 115.54, 62.17, 47.76, 26.01, 24.57, 21.61.
1-Acetyl-5-(4-fluorophenyl)-3-methyl-3-(tosylmethyl)-1H-pyrrol-2(3H)-one (3b): 1H NMR (400 MHz, CDCl3) δ 7.71 (d, J = 8.2 Hz, 2H), 7.29 (d, J = 8.1 Hz, 2H), 7.26–7.20 (m, 2H), 7.05 (t, J = 8.7 Hz, 2H), 5.53 (s, 1H), 3.69 (d, J = 14.3 Hz, 1H), 3.45 (d, J = 14.3 Hz, 1H), 2.50 (s, 3H), 2.43 (s, 3H), 1.39 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 179.56, 169.33, 162.72 (J = 252 Hz), 145.15, 142.02, 136.61, 129.94, 128.85, 128.77, 128.14, 115.66, 115.06, 114.85, 62.22, 47.69, 26.05, 24.53, 21.63. 19F NMR (565 MHz, CDCl3) δ-112.68.
1-Acetyl-5-(4-chlorophenyl)-3-methyl-3-(tosylmethyl)-1H-pyrrol-2(3H)-one (3c): 1H NMR (600 MHz, CDCl3) δ 7.70 (d, J = 8.3 Hz, 2H), 7.33 (d, J = 8.5 Hz, 2H), 7.29 (d, J = 8.0 Hz, 2H), 7.19 (d, J = 8.5 Hz, 2H), 5.56 (s, 1H), 3.68 (d, J = 14.3 Hz, 1H), 3.45 (d, J = 14.3 Hz, 1H), 2.50 (s, 3H), 2.43 (s, 3H), 1.39 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 179.46, 169.26, 145.16, 141.90, 136.55, 134.39, 131.26, 129.94, 128.23, 128.13, 128.13, 116.05, 62.19, 47.74, 25.97, 24.48, 21.62.
1-acetyl-5-(4-bromophenyl)-3-methyl-3-(tosylmethyl)-1H-pyrrol-2(3H)-one (3d). 1H NMR (600 MHz, CDCl3) δ 7.70 (d, J = 8.2 Hz, 2H), 7.49 (d, J = 8.4 Hz, 2H), 7.29 (d, J = 8.0 Hz, 2H), 7.13 (d, J = 8.4 Hz, 2H), 5.56 (s, 1H), 3.68 (d, J = 14.3 Hz, 1H), 3.44 (d, J = 14.3 Hz, 1H), 2.50 (s, 3H), 2.43 (s, 3H), 1.39 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 179.45, 169.27, 145.19, 141.95, 136.53, 131.74, 131.08, 129.96, 128.49, 128.14, 122.60, 116.10, 62.18, 47.77, 25.99, 24.47, 21.65.
1-Acetyl-5-(4-iodophenyl)-3-methyl-3-(tosylmethyl)-1H-pyrrol-2(3H)-one (3e). 1H NMR (400 MHz, CDCl3) δ 7.69 (dd, J = 8.0, 2.4 Hz, 4H), 7.29 (d, J = 7.9 Hz, 2H), 6.99 (d, J = 7.6 Hz, 2H), 5.56 (s, 1H), 3.69 (d, J = 14.2 Hz, 1H), 3.45 (d, J = 14.3 Hz, 1H), 2.50 (s, 3H), 2.43 (s, 3H), 1.38 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 179.41, 169.24, 145.16, 141.99, 136.97, 136.44, 132.28, 129.93, 128.55, 128.11, 116.10, 94.28, 62.12, 47.75, 25.95, 24.44, 21.63.
Methyl-4-(1-acetyl-4-methyl-5-oxo-4-(tosylmethyl)-4,5-dihydro-1H-pyrrol-2-yl)benzoate (3f). 1H NMR (600 MHz, CDCl3) δ 8.03 (d, J = 8.3 Hz, 2H), 7.70 (d, J = 8.2 Hz, 2H), 5.61 (s, 1H), 3.93 (s, 3H), 3.70 (d, J = 14.4 Hz, 1H), 3.48 (d, J = 14.4 Hz, 1H), 2.52 (s, 3H), 2.42 (s, 3H), 1.40 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 179.34, 169.17, 166.61, 145.19, 142.05, 137.21, 136.50, 129.95, 129.20, 128.14, 126.77, 116.93, 62.17, 52.20, 47.90, 25.85, 24.43, 21.62.
1-Acetyl-3-methyl-5-p-tolyl-3-(tosylmethyl)-1H-pyrrol-2(3H)-one (3g). 1H NMR (400 MHz, CDCl3) δ 7.71 (d, J = 8.3 Hz, 2H), 7.27 (d, J = 8.1 Hz, 2H), 7.17 (d, J = 8.1 Hz, 2H), 7.13 (d, J = 8.3 Hz, 2H), 5.49 (s, 1H), 3.69 (d, J = 14.4 Hz, 1H), 3.45 (d, J = 14.4 Hz, 1H), 2.47 (s, 3H), 2.42 (s, 3H), 2.38 (s, 3H), 1.39 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 179.68, 169.28, 145.03, 142.88, 138.45, 136.57, 129.90, 129.76, 128.62, 128.26, 126.71, 114.96, 62.18, 47.72, 26.09, 24.61, 21.62, 21.37.
1-Acetyl-5-(4-methoxyphenyl)-3-methyl-3-(tosylmethyl)-1H-pyrrol-2(3H)-one (3h). 1H NMR (400 MHz, CDCl3) δ 7.71 (d, J = 8.3 Hz, 2H), 7.20–7.10 (m, 2H), 6.89 (d, J = 8.8 Hz, 2H), 5.45 (s, 1H), 3.84 (s, 3H), 3.69 (d, J = 14.3 Hz, 1H), 3.45 (d, J = 14.4 Hz, 1H), 2.48 (s, 3H), 2.42 (s, 3H), 1.38 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 179.75, 169.41, 159.75, 145.04, 142.62, 136.59, 129.89, 128.25, 128.23, 125.05, 114.47, 113.35, 62.21, 55.32, 47.64, 26.17, 24.65, 21.63.
1-Acetyl-5-(3-bromophenyl)-3-methyl-3-(tosylmethyl)-1H-pyrrol-2(3H)-one (3i). 1H NMR (600 MHz, CDCl3) δ 7.70 (d, J = 8.0 Hz, 2H), 7.47 (d, J = 7.7 Hz, 1H), 7.35 (s, 1H), 7.31 (d, J = 8.0 Hz, 2H), 7.22 (t, J = 7.9 Hz, 1H), 7.16 (d, J = 7.7 Hz, 1H), 5.51 (s, 1H), 3.69 (d, J = 14.4 Hz, 1H), 3.47 (d, J = 14.4 Hz, 1H), 2.52 (s, 3H), 2.45 (s, 3H), 1.39 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 179.33, 169.17, 145.20, 141.52, 136.52, 134.71, 131.45, 129.99, 129.66, 129.33, 128.17, 125.56, 121.91, 116.51, 62.15, 47.79, 25.89, 24.43, 21.66.
1-Acetyl-3-methyl-5-m-tolyl-3-(tosylmethyl)-1H-pyrrol-2(3H)-one (3j). 1H NMR (400 MHz, CDCl3) δ 7.74–7.66 (m, 2H), 7.28 (d, J = 7.9 Hz, 2H), 7.24 (d, J = 7.6 Hz, 1H), 7.16 (d, J = 7.6 Hz, 1H), 7.05 (s, 1H), 7.02 (d, J = 7.6 Hz, 1H), 5.49 (s, 1H), 3.69 (d, J = 14.3 Hz, 1H), 3.46 (d, J = 14.4 Hz, 1H), 2.49 (s, 3H), 2.43 (s, 3H), 2.37 (s, 3H), 1.39 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 179.64, 169.22, 145.03, 142.97, 137.58, 136.58, 132.58, 129.92, 129.34, 128.26, 127.76, 127.32, 123.89, 115.35, 62.17, 47.76, 26.05, 24.58, 21.63, 21.46.
1-Acetyl-5-(2-chlorophenyl)-3-methyl-3-(tosylmethyl)-1H-pyrrol-2(3H)-one (3k). 1H NMR (600 MHz, CDCl3) δ 7.78 (d, J = 8.0 Hz, 2H), 7.43 (s, 1H), 7.34 (dt, J = 14.4, 4.1 Hz, 5H), 5.68 (s, 1H), 3.66 (s, 1H), 3.44 (d, J = 14.2 Hz, 1H), 2.44 (d, J = 9.1 Hz, 6H), 1.45 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 178.67, 168.78, 145.16, 132.80, 129.98, 129.92, 129.82, 128.88, 128.11, 126.70, 116.75, 61.92, 47.61, 25.34, 24.43, 21.61.
1-Acetyl-3-methyl-5-o-tolyl-3-(tosylmethyl)-1H-pyrrol-2(3H)-one (3l). 1H NMR (600 MHz, CDCl3) δ 7.78 (d, J = 8.0 Hz, 2H), 7.33 (d, J = 8.0 Hz, 2H), 7.28 (d, J = 7.4 Hz, 1H), 7.19 (dd, J = 15.2, 7.4 Hz, 2H), 5.58 (s, 1H), 3.67 (d, J = 14.0 Hz, 1H), 3.42 (d, J = 14.0 Hz, 1H), 2.48 (s, 3H), 2.43 (s, 3H), 2.26 (s, 3H), 1.41 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 179.56, 168.91, 145.09, 136.91, 133.15, 129.98, 129.57, 128.60, 128.41, 128.00, 125.37, 115.27, 62.16, 47.39, 25.73, 24.93, 21.63, 19.80.
1-Acetyl-4-ethyl-3-methyl-5-phenyl-3-(tosylmethyl)-1H-pyrrol-2(3H)-one (3m). 1H NMR (600 MHz, CDCl3) δ 7.76 (d, J = 7.9 Hz, 2H), 7.39 (t, J = 7.3 Hz, 2H), 7.36 (d, J = 7.2 Hz, 1H), 7.34–7.27 (m, 4H), 3.70 (d, J = 14.3 Hz, 1H), 3.49 (d, J = 14.3 Hz, 1H), 2.44 (s, 3H), 2.43 (s, 3H), 2.21 (dd, J = 15.2, 7.7 Hz, 1H), 1.94 (dd, J = 15.0, 7.5 Hz, 1H), 1.38 (s, 3H), 0.91 (t, J = 7.6 Hz, 3H). 13C NMR (151 MHz, CDCl3) δ 179.42, 169.08, 145.02, 137.67, 136.88, 132.56, 129.92, 128.32, 128.13, 128.00, 127.93, 126.10, 61.75, 50.46, 26.18, 24.64, 21.63, 18.04, 14.58.
1-Acetyl-3-butyl-5-phenyl-3-(tosylmethyl)-1H-pyrrol-2(3H)-one (3n). 1H NMR (600 MHz, CDCl3) δ 7.70 (d, J = 8.1 Hz, 2H), 7.38–7.34 (m, 4H), 7.26 (d, J = 5.4 Hz, 5H), 5.42 (s, 1H), 3.69 (d, J = 14.4 Hz, 1H), 3.49 (d, J = 14.4 Hz, 1H), 2.49 (s, 3H), 2.41 (s, 3H), 1.75–1.67 (m, 2H), 1.27 (s, 3H), 1.11 (d, J = 11.6 Hz, 1H), 0.85 (t, J = 7.0 Hz, 3H). 13C NMR (151 MHz, CDCl3) δ 179.40, 169.09, 145.00, 143.77, 136.68, 132.82, 129.88, 128.48, 128.22, 127.90, 126.82, 114.00, 61.79, 51.71, 38.07, 26.05, 25.64, 22.60, 21.61, 13.75.
3-Methyl-5-phenyl-1-propionyl-3-(tosylmethyl)-1H-pyrrol-2(3H)-one (3o). 1H NMR (600 MHz, CDCl3) δ 7.70 (d, J = 8.2 Hz, 2H), 7.38–7.33 (m, 3H), 7.27 (d, J = 5.6 Hz, 2H), 7.23 (dd, J = 6.5, 2.9 Hz, 2H), 5.51 (s, 1H), 3.70 (d, J = 14.4 Hz, 1H), 3.45 (d, J = 14.4 Hz, 1H), 2.95–2.81 (m, 2H), 2.41 (s, 3H), 1.39 (s, 3H), 1.14 (t, J = 7.3 Hz, 3H). 13C NMR (151 MHz, CDCl3) δ 179.43, 173.23, 145.03, 143.01, 136.60, 132.85, 129.87, 128.48, 128.22, 127.93, 126.70, 115.49, 62.16, 47.83, 31.58, 24.63, 21.62, 8.33.
1-Isobutyryl-3-methyl-5-phenyl-3-(tosylmethyl)-1H-pyrrol-2(3H)-one (3p). 1H NMR (600 MHz, CDCl3) δ 1H NMR (600 MHz, CDCl3) δ 7.69 (d, J = 8.3 Hz, 2H), 7.36 (dd, J = 5.0, 1.8 Hz, 3H), 7.24 (d, J = 8.0 Hz, 2H), 7.19 (dd, J = 6.5, 3.1 Hz, 2H), 5.49 (s, 1H), 3.70 (d, J = 14.4 Hz, 1H), 3.66 (s, 1H), 3.46 (d, J = 14.4 Hz, 1H), 2.40 (s, 3H), 1.40 (s, 3H), 1.24 (d, J = 6.9 Hz, 3H), 1.18 (d, J = 6.8 Hz, 3H). 13C NMR (151 MHz, CDCl3) δ 178.91, 176.67, 144.97, 143.15, 136.68, 132.81, 129.86, 128.49, 128.18, 128.05, 126.22, 115.31, 62.11, 48.11, 35.57, 24.69, 21.62, 18.60, 18.37.
1-Acetyl-3-methyl-5-phenyl-3-(phenylsulfonylmethyl)-1H-pyrrol-2(3H)-one (4a). 1H NMR (600 MHz, CDCl3) δ 7.84 (d, J = 7.6 Hz, 2H), 7.63 (t, J = 7.4 Hz, 1H), 7.49 (t, J = 7.8 Hz, 2H), 7.37–7.33 (m, 3H), 7.24 (dd, J = 6.4, 2.6 Hz, 2H), 5.50 (s, 1H), 3.71 (d, J = 14.4 Hz, 1H), 3.49 (d, J = 14.4 Hz, 1H), 2.51 (s, 3H), 1.41 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 179.58, 169.29, 143.05, 139.60, 133.94, 132.63, 129.30, 128.54, 128.17, 127.92, 126.76, 115.37, 62.13, 47.78, 26.07, 24.53.
1-Acetyl-3-((4-methoxyphenylsulfonyl)methyl)-3-methyl-5-phenyl-1H-pyrrol-2(3H)-one (4b). 1H NMR (600 MHz, CDCl3) δ 7.74 (d, J = 8.8 Hz, 2H), 7.42–7.32 (m, 3H), 6.91 (d, J = 8.9 Hz, 2H), 5.50 (s, 1H), 3.84 (s, 3H), 3.70 (d, J = 14.4 Hz, 1H), 3.45 (d, J = 14.4 Hz, 1H), 2.50 (s, 3H), 1.39 (s, 3H).13C NMR (151 MHz, CDCl3) δ 179.60, 169.30, 163.90, 142.80, 132.71, 130.90, 130.46, 128.50, 127.90, 126.77, 115.66, 114.45, 62.36, 55.73, 47.80, 26.04, 24.64.
1-Acetyl-3-((4-tert-butylphenylsulfonyl)methyl)-3-methyl-5-phenyl-1H-pyrrol-2(3H)-one (4c). 1H NMR (600 MHz, CDCl3) δ 7.73 (d, J = 8.5 Hz, 2H), 7.47 (d, J = 8.5 Hz, 2H), 7.38–7.32 (m, 3H), 7.21 (dd, J = 3.9, 1.8 Hz, 2H), 5.45 (s, 1H), 3.71 (d, J = 14.4 Hz, 1H), 3.48 (d, J = 14.4 Hz, 1H), 2.50 (s, 3H), 1.40 (s, 3H), 1.32 (s, 9H). 13C NMR (151 MHz, CDCl3) δ 179.57, 169.24, 157.94, 142.81, 136.43, 132.64, 128.49, 128.04, 127.88, 126.73, 126.32, 115.56, 62.07, 47.75, 35.27, 31.02, 26.10, 24.55.
1-Acetyl-3-methyl-5-phenyl-3-((m-tolylsulfonyl)methyl)-1,3-dihydro-2H-pyrrol-2-one (4d). White solid; mp 136.3–138.0 °C; 1H NMR (600 MHz, CDCl3) δ 7.62 (d, J = 11.2 Hz, 2H), 7.41 (d, J = 7.6 Hz, 1H), 7.39–7.33 (m, 4H), 7.24 (dd, J = 6.6, 2.9 Hz, 2H), 5.46 (s, 1H), 3.71 (d, J = 14.4 Hz, 1H), 3.48 (d, J = 14.4 Hz, 1H), 2.53 (s, 3H), 2.32 (s, 3H), 1.40 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 179.65, 169.31, 143.07, 139.70, 139.47, 134.73, 132.68, 129.17, 128.54, 128.48, 127.93, 126.77, 125.22, 115.33, 62.13, 47.79, 26.08, 24.51, 21.19. HRMS (ESI, m/z): Calcd. For C21H21NSO4Na [M + Na]+ 406.1083, found: 406.1085.
1-Acetyl-3-(((2-methoxyphenyl)sulfonyl)methyl)-3-methyl-5-phenyl-1,3-dihydro-2H-pyrrol-2-one (4e). White solid; mp 123.4–125.0 °C; 1H NMR (600 MHz, CDCl3) δ 7.76 (dd, J = 7.8, 1.7 Hz, 1H), 7.59–7.53 (m, 1H), 7.34–7.29 (m, 3H), 7.12 (dd, J = 6.5, 3.1 Hz, 2H), 7.03 (d, J = 8.3 Hz, 1H), 6.95 (t, J = 7.6 Hz, 1H), 5.37 (s, 1H), 4.02 (s, 3H), 3.95 (d, J = 14.5 Hz, 1H), 3.77 (d, J = 14.6 Hz, 1H), 2.47 (s, 3H), 1.39 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 179.69, 169.24, 157.38, 142.70, 135.86, 132.68, 130.67, 128.39, 127.79, 127.19, 126.65, 120.87, 115.64, 112.35, 60.13, 56.47, 47.69, 26.00, 24.55. HRMS (ESI, m/z): Calcd. For C21H21NO5SNa [M + Na]+ 422.1033, found: 422.1038.
1-Acetyl-3-((4-bromophenylsulfonyl)methyl)-3-methyl-5-phenyl-1H-pyrrol-2(3H)-one (4f). 1H NMR (400 MHz, CDCl3) δ 7.67 (d, J = 8.0 Hz, 2H), 7.61 (d, J = 7.9 Hz, 2H), 7.36 (s, 3H), 7.22 (s, 2H), 5.48 (s, 1H), 3.70 (d, J = 14.4 Hz, 1H), 3.46 (d, J = 14.3 Hz, 1H), 2.52 (s, 3H), 1.39 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 179.45, 169.28, 143.22, 138.49, 132.66, 132.50, 129.75, 129.44, 128.67, 128.01, 126.71, 115.17, 62.20, 47.77, 26.03, 24.57. HRMS (ESI, m/z): Calcd. For C20H18NO4SBrNa [M + Na]+ 470.0032, found: 470.0035.
1-Acetyl-3-((4-iodophenylsulfonyl)methyl)-3-methyl-5-phenyl-1H-pyrrol-2(3H)-one (4g). 1H NMR (600 MHz, CDCl3) δ 7.84 (d, J = 8.3 Hz, 2H), 7.52 (d, J = 8.4 Hz, 2H), 7.37 (d, J = 1.6 Hz, 3H), 7.22 (d, J = 3.6 Hz, 2H), 5.49 (s, 1H), 3.70 (d, J = 14.4 Hz, 1H), 3.46 (d, J = 14.4 Hz, 1H), 2.52 (s, 3H), 1.40 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 179.41, 169.25, 143.17, 139.09, 138.63, 132.47, 129.49, 128.65, 127.99, 126.69, 115.16, 102.04, 62.12, 47.73, 26.03, 24.58.
4-(((1-Acetyl-3-methyl-2-oxo-5-phenyl-2,3-dihydro-1H-pyrrol-3-yl)methyl)sulfonyl)benzonitrile (4h). White solid; mp 189.4–191.5 °C; 1H NMR (600 MHz, CDCl3) δ 7.94 (d, J = 8.1 Hz, 2H), 7.76 (d, J = 8.1 Hz, 2H), 7.38 (s, 3H), 7.22 (d, J = 3.2 Hz, 2H), 5.43 (s, 1H), 3.72 (d, J = 14.4 Hz, 1H), 3.52 (d, J = 14.4 Hz, 1H), 2.55 (s, 3H), 1.41 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 179.31, 169.26, 143.63, 143.57, 133.03, 132.35, 128.87, 128.79, 128.06, 126.61, 117.72, 116.90, 114.77, 62.11, 47.75, 26.05, 24.39. HRMS (ESI, m/z): Calcd. For C21H18N2O4SNa [M + Na]+ 417.0879, found: 417.0883.
1-Acetyl-3-methyl-5-phenyl-3-((4(trifluoromethyl)phenylsulfonyl)methyl)-1H-pyrrol-2(3H)-one (4i). 1H NMR (400 MHz, CDCl3) δ 7.96 (d, J = 7.7 Hz, 2H), 7.74 (d, J = 7.7 Hz, 2H), 7.37 (s, 3H), 7.21 (s, 2H), 5.45 (s, 1H), 3.74 (d, J = 14.4 Hz, 1H), 3.52 (d, J = 14.4 Hz, 1H), 2.52 (s, 3H), 1.41 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 179.35, 169.30, 143.37, 142.98, 135.63 (J = 32 Hz), 132.38, 128.86, 128.74, 128.03, 126.63, 126.48 (J = 3 Hz), 125.28 (J = 250 Hz), 114.99, 76.75, 62.08, 47.74, 26.03, 24.53. 19F NMR (565 MHz, CDCl3) δ-63.25.
1-Acetyl-3-methyl-3-((4-nitrophenylsulfonyl)methyl)-5-phenyl-1H-pyrrol-2(3H)-one (4j). 1H NMR (400 MHz, CDCl3) δ 8.29 (d, J = 8.1 Hz, 2H), 8.01 (d, J = 8.3 Hz, 2H), 7.37 (s, 3H), 7.22 (d, J = 3.7 Hz, 2H), 5.44 (s, 1H), 3.74 (d, J = 14.3 Hz, 1H), 3.54 (d, J = 14.4 Hz, 1H), 2.55 (s, 3H), 1.41 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 179.29, 169.27, 150.85, 145.06, 143.63, 132.28, 129.62, 128.80, 128.06, 126.57, 124.44, 114.68, 62.16, 47.75, 26.05, 24.38.
1-Acetyl-3-((3-chlorophenylsulfonyl)methyl)-3-methyl-5-phenyl-1H-pyrrol-2(3H)-one (4k). 1H NMR (400 MHz, CDCl3) δ 7.82 (s, 1H), 7.72 (d, J = 7.3 Hz, 1H), 7.60 (d, J = 7.8 Hz, 1H), 7.43 (t, J = 7.9 Hz, 1H), 7.36 (s, 2H), 7.26 (s, 2H), 5.49 (s, 1H), 3.72 (d, J = 14.4 Hz, 1H), 3.50 (d, J = 14.4 Hz, 1H), 2.55 (s, 3H), 1.41 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 179.45, 169.26, 143.35, 141.29, 135.56, 134.13, 132.44, 130.61, 128.60, 128.13, 127.96, 126.70, 126.27, 114.91, 62.13, 47.75, 26.08, 24.45.
1-Acetyl-3-((2-chlorophenylsulfonyl)methyl)-3-methyl-5-phenyl-1H-pyrrol-2(3H)-one (4l). 1H NMR (400 MHz, CDCl3) δ 7.91 (d, J = 7.7 Hz, 1H), 7.52 (d, J = 6.7 Hz, 2H), 7.33 (s, 3H), 7.26–7.20 (m, 1H), 7.13 (d, J = 3.3 Hz, 2H), 5.29 (s, 1H), 3.92 (s, 2H), 2.53 (s, 3H), 1.40 (s, 3H). 13C NMR (101 MHz, CDCl3) δ 179.38, 169.33, 143.22, 137.02, 134.93, 132.62, 132.48, 131.84, 128.52, 127.86, 127.46, 126.52, 115.06, 60.08, 47.68, 26.05, 24.38.
1-Acetyl-3-methyl-5-phenyl-3-((thiophen-2ylsulfonyl)methyl)-1H-pyrrol-2(3H)-one (4m). 1H NMR (600 MHz, CDCl3) δ 7.70 (d, J = 4.4 Hz, 1H), 7.62 (d, J = 3.0 Hz, 1H), 7.40–7.33 (m, 3H), 7.26 (d, J = 4.9 Hz, 2H), 7.11–7.02 (m, 1H), 5.59 (s, 1H), 3.82 (d, J = 14.4 Hz, 1H), 3.59 (d, J = 14.4 Hz, 1H), 2.53 (s, 3H), 1.43 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 179.45, 169.26, 143.15, 140.70, 134.67, 134.58, 132.61, 128.55, 127.92, 126.84, 115.19, 63.58, 47.89, 26.09, 24.46.
1-Acetyl-3-(cyclopropylsulfonylmethyl)-3-methyl-5-phenyl-1H-pyrrol-2(3H)-one (4n). 1H NMR (600 MHz, CDCl3) δ 7.36–7.33 (m, 3H), 7.28 (dd, J = 6.5, 2.9 Hz, 2H), 5.72 (s, 1H), 3.62 (d, J = 14.0 Hz, 1H), 3.41 (d, J = 14.0 Hz, 1H), 2.57 (s, 3H), 2.41–2.36 (m, 1H), 1.47 (s, 3H), 1.28–1.25 (m, 1H), 1.21 (dd, J = 4.8, 1.8 Hz, 1H), 1.05–1.01 (m, 2H). 13C NMR (151 MHz, CDCl3) δ 179.93, 169.38, 143.37, 132.73, 128.53, 127.93, 126.93, 115.39, 59.87, 47.49, 31.27, 26.11, 24.19, 5.35, 5.14.
1-Acetyl-3-((ethylsulfonyl)methyl)-3-methyl-5-phenyl-1,3-dihydro-2H-pyrrol-2-one (4o). Amorphous solid; 1H NMR (600 MHz, CDCl3) δ 7.37–7.32 (m, 3H), 7.28 (dd, J = 6.6, 3.0 Hz, 2H), 5.69 (s, 1H), 3.49 (d, J = 13.9 Hz, 1H), 3.33 (d, J = 13.9 Hz, 1H), 2.98 (d, J = 7.5 Hz, 2H), 2.57 (s, 3H), 1.46 (s, 3H), 1.38 (t, J = 7.5 Hz, 3H). 13C NMR (151 MHz, CDCl3) δ 179.90, 169.36, 143.63, 132.75, 128.55, 127.93, 126.97, 115.02, 57.84, 49.54, 47.30, 26.11, 24.15, 6.57. HRMS (ESI, m/z): Calcd. For C16H19NSO4Na [M + Na]+ 344.0927, found: 344.0932.
3-Methyl-5-phenyl-3-((phenylsulfonyl)methyl)-1,3-dihydro-2H-pyrrol-2-one (4aa). White solid; mp 186.5–188.4 °C; 1H NMR (600 MHz, CDCl3) δ 8.60 (s, 1H), 7.83 (d, J = 7.3 Hz, 2H), 7.60 (t, J = 7.5 Hz, 1H), 7.48–7.42 (m, 6H), 7.39 (dd, J = 8.2, 5.6 Hz, 1H), 5.75 (d, J = 1.8 Hz, 1H), 3.61 (d, J = 14.3 Hz, 1H), 3.50 (d, J = 14.3 Hz, 1H), 1.44 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 182.28, 139.99, 139.92, 133.78, 129.49, 129.35, 129.08, 128.94, 128.18, 124.94, 107.88, 77.24, 77.03, 76.82, 61.68, 48.27, 23.52. HRMS (ESI, m/z): Calcd. For C18H17NO3SNa [M + Na]+ 350.0821, found: 350.0827.
(2-Tosylethene-1,1-diyl)dibenzene. 1H NMR (600 MHz, CDCl3) δ 7.47 (d, J = 8.1 Hz, 2H), 7.37 (dd, J = 14.0, 7.4 Hz, 2H), 7.30 (t, J = 7.6 Hz, 4H), 7.20 (d, J = 7.6 Hz, 2H), 7.15 (d, J = 8.1 Hz, 2H), 7.10 (d, J = 7.4 Hz, 2H), 6.99 (s, 1H), 2.38 (s, 3H). 13C NMR (151 MHz, CDCl3) δ 154.71, 143.76, 139.26, 138.63, 135.59, 130.23, 129.79, 129.34, 128.98, 128.85, 128.65, 128.58, 128.22, 127.82, 127.71, 126.05, 21.58.

4. Conclusions

In conclusion, we developed a visible-light-induced, regioselective cascade sulfonylation/cyclization of 1,5-dienes with sulfonyl chlorides. A variety of structurally significant pyrrolinones with important classes of sulfonyl group patterns were obtained in medium to high yields. This methodology features sulfonyl radical addition/cyclization of alkenes C(sp2)-H with high regioselectivity under very mild conditions and tolerated broad functional groups.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/molecules28145473/s1. Section S1, General information. Section S2, Procedure for the synthesis of compound 3a–3p, 4a–4o. Section S3, Procedures for the formation of compound 4aa. Section S4, The Transformation with the Light ON/OFF over Time. Section S5, The radical trapping reaction residue. Section S6, NMR spectra for the products.

Author Contributions

R.D. supervised the project and wrote the manuscript; B.Z. analyzed the data and discussed with R.D. and P.-L.W.; L.L., Y.-T.Y. and R.D. conducted the experiments. All authors contributed to the revision. All authors have read and agreed to the published version of the manuscript.

Funding

We gratefully acknowledge the funding support of Anhui Province Research Funding for Outstanding Young Talents in Colleges and Universities, China (No. gxyqZD2022098), Key Laboratory of Green and Precise Synthetic Chemistry and Applications, Ministry of Education (No. 2020KF02), and Anhui Grant New Material Company (No. 9341064).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Conflicts of Interest

The authors declare no conflict of interest.

Sample Availability

Samples of the compounds are available from the authors.

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Molecules 28 05473 g001 550
Figure 1. Examples of compounds containing pyrrolin-2-ones.
Figure 1. Examples of compounds containing pyrrolin-2-ones.
Molecules 28 05473 g001
Molecules 28 05473 sch001 550
Scheme 1. Radical cyclization of tethered alkenes. Challenge i: Regioselectivity of sulfone radical addition; Challenge ii: Two pathway of cyclization; Challenge iii: 3,4-disulfonated pyrrolin-2-ones.
Scheme 1. Radical cyclization of tethered alkenes. Challenge i: Regioselectivity of sulfone radical addition; Challenge ii: Two pathway of cyclization; Challenge iii: 3,4-disulfonated pyrrolin-2-ones.
Molecules 28 05473 sch001
Molecules 28 05473 g002 550
Figure 2. Substrate Scope of 1,5-dienes. Reaction conditions: 1 (0.1 mmol), 2a (0.2 mmol), and Ir(ppy)3 (1 mol%) in CH2Cl2 (1 mL) were irradiated with 5 W white LEDs at room temperature under N2 for 16 h. The yields were isolated yields.
Figure 2. Substrate Scope of 1,5-dienes. Reaction conditions: 1 (0.1 mmol), 2a (0.2 mmol), and Ir(ppy)3 (1 mol%) in CH2Cl2 (1 mL) were irradiated with 5 W white LEDs at room temperature under N2 for 16 h. The yields were isolated yields.
Molecules 28 05473 g002
Molecules 28 05473 g003 550
Figure 3. Substrate scope of sulfonyl chlorides. Reaction conditions: a mixture of 1a (0.1 mmol), 2 (0.2 mmol), and Ir(ppy)3 (1 mol%) in CH2Cl2 (1 mL), which were irradiated with 5 W white LEDs at room temperature under N2 for 16 h. The yields were isolated yields. c 20 W white LEDs were used.
Figure 3. Substrate scope of sulfonyl chlorides. Reaction conditions: a mixture of 1a (0.1 mmol), 2 (0.2 mmol), and Ir(ppy)3 (1 mol%) in CH2Cl2 (1 mL), which were irradiated with 5 W white LEDs at room temperature under N2 for 16 h. The yields were isolated yields. c 20 W white LEDs were used.
Molecules 28 05473 g003
Molecules 28 05473 sch002 550
Scheme 2. Gram−scale reaction and removal of OAc group. (1): Gram-scale reaction; (2): Removal of OAc group.
Scheme 2. Gram−scale reaction and removal of OAc group. (1): Gram-scale reaction; (2): Removal of OAc group.
Molecules 28 05473 sch002
Molecules 28 05473 sch003 550
Scheme 3. Mechanistic studies. (1): TEMPO (2.0 equiv.) was added; (2): 1,1-diphenylethylene (2.0 equiv.) was added.
Scheme 3. Mechanistic studies. (1): TEMPO (2.0 equiv.) was added; (2): 1,1-diphenylethylene (2.0 equiv.) was added.
Molecules 28 05473 sch003
Molecules 28 05473 sch004 550
Scheme 4. Proposed reaction mechanism.
Scheme 4. Proposed reaction mechanism.
Molecules 28 05473 sch004
Table
Table 1. Optimization of the reaction conditions a.
Table 1. Optimization of the reaction conditions a.
Molecules 28 05473 i001
EntryCatalyst (1 mol%)Base (Equiv.)SolventYield b
1fac-Ir(ppy)3Na2CO3 (1.0)CH2Cl257%
2Ru(bpy)3Cl2Na2CO3 (1.0)CH2Cl2trace
3Eosin YNa2CO3 (1.0)CH2Cl2trace
4fac-Ir(ppy)3K2CO3 (1.0)CH2Cl266%
5fac-Ir(ppy)3Li2CO3 (1.0)CH2Cl259%
6fac-Ir(ppy)3NaHCO3 (1.0)CH2Cl264%
7fac-Ir(ppy)3K3PO4 (1.0)CH2Cl272%
8fac-Ir(ppy)3Na3PO4 (1.0)CH2Cl263%
9fac-Ir(ppy)3K3PO4 (1.0)DCE55%
10fac-Ir(ppy)3K3PO4 (1.0)CHCl362%
11fac-Ir(ppy)3K3PO4 (1.0)Acetone67%
12fac-Ir(ppy)3K3PO4 (1.0)Toluene44%
13fac-Ir(ppy)3K3PO4 (1.0)THF59%
14fac-Ir(ppy)3K3PO4 (1.0)EtOAc32%
15fac-Ir(ppy)3K3PO4 (1.5)CH2Cl279%
16fac-Ir(ppy)3K3PO4 (2.0)CH2Cl279%
17 cfac-Ir(ppy)3K3PO4 (1.5)CH2Cl279%
18 c------K3PO4 (1.5)CH2Cl20%
19 cfac-Ir(ppy)3------CH2Cl216%
20 dfac-Ir(ppy)3K3PO4 (1.5)CH2Cl20%
a Reaction conditions: 1a (0.1 mmol), 2a (0.2 mmol), and catalyst (1 mol%) in solvent (1 mL), which were irradiated with 20 W white LEDs at room temperature under N2 for 16 h. b Isolated yields. c 5 W white LEDs was used. d The reaction was conducted in darkness.
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Ding, R.; Li, L.; Yu, Y.-T.; Zhang, B.; Wang, P.-L. Photoredox-Catalyzed Synthesis of 3-Sulfonylated Pyrrolin-2-ones via a Regioselective Tandem Sulfonylation Cyclization of 1,5-Dienes. Molecules 2023, 28, 5473. https://doi.org/10.3390/molecules28145473

AMA Style

Ding R, Li L, Yu Y-T, Zhang B, Wang P-L. Photoredox-Catalyzed Synthesis of 3-Sulfonylated Pyrrolin-2-ones via a Regioselective Tandem Sulfonylation Cyclization of 1,5-Dienes. Molecules. 2023; 28(14):5473. https://doi.org/10.3390/molecules28145473

Chicago/Turabian Style

Ding, Ran, Liang Li, Ya-Ting Yu, Bing Zhang, and Pei-Long Wang. 2023. "Photoredox-Catalyzed Synthesis of 3-Sulfonylated Pyrrolin-2-ones via a Regioselective Tandem Sulfonylation Cyclization of 1,5-Dienes" Molecules 28, no. 14: 5473. https://doi.org/10.3390/molecules28145473

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