English

• 1.   Introduction

  Vinyl sulfone compounds are broadly utilized in natural products and medicinal chemistry.^[1] In organic chemistry, vinyl sulfones are also effective Michael acceptors and 2π partners in cycloaddition reactions.^[2] Because of the importance of vinyl sulfones, much efforts have been paid for developing various efficient methods for their synthesis. At present, various approaches for the synthesis of vinyl sulfones have been established.^[3] The coupling reaction of sodium sulfinate with alkenes or alkynes is one of these methods for the synthesis of vinyl sulfones.^[4] For example, in 2016, an Mn(Ⅲ)-mediated regioselective synthesis of (E)-vinyl sulfones from sodium sulfinates and nitroolefins was described by Chen's group (Scheme 1a).^[5] Arylsulfonyl hydrazides are also good partners to react with olefins (Scheme 1b), ^[6] cinnamic acids (Scheme 1c)^[7] or alkyne derivatives (Scheme 1d)^[8] for the synthesis of vinyl sulfones. While significant developments have been made, some disadvantages such as metal catalyst or high temperature are needed for some of these methods, which limit their further application. Developing new versatile and practical methods for synthesis of vinyl sulfones still remain desirable.

  Scheme 1

  

  Scheme 1.  Synthesis of vinyl sulfones

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  Since the pioneering work on visible light-induced organic reactions by MacMillan, ^[9] visible-light induced reactions have received wide research interest in recent years because of its green and sustainable chemistry character.^[10] Among various visible-light induced organic transformations, great progress has been made on C—S bond formation reactions.^[11] In the photoredox catalytic process, a variety of S—H, S—S, S—C, S—N, and S—X (F, Cl, Br, I) bonds, and even active sulfone-containing skeletons can be easily transformed into the corresponding thioyl/sul- fonyl radicals.^[12] Wang group^[13] described a visible-light- induced direct thiolation at α-C(sp³)—H of ethers with diaryl disulfides for the preparation of α-arylthioethers. The oxysulfonylation of alkenes with arylsulfinic acids was achieved by Yang et al.^[14] under visible light leading to keto sulfones. A photoredox process for the synthesis of vinyl sulfones from alkenes and aryl sulfinates was developed by Meyer and co-workers.^[15] Sun et al.^[16] found that sulfonylated isoquinolinediones can be synthesized efficiently under irradiation of 5 W blue LED (light emitting diode) with sulfonyl chlorides as sulfonyl source. Using O₂ as sole terminal oxidant, a visible light-promoted decarboxylative cross- coupling reaction of cinnamate acids with sulfonyl hydrazides was presented by Cai's group.^[17] In consistence with our research interest in C—H bond activation and green chemistry, ^[18] herein we describe a new protocol to access vinyl sulfones via visible-light induced sulfonylation of nitroolefins under photocatalyst free conditions.

  2.   Results and discussion

  The sulfonylation of (E)-(2-nitrovinyl)benzene with sulfinic acid was selected as a model reaction. To our delight, the product 3a was obtained in 59% yield in the presence of N-hydroxyphthalimide (NHPI) as catalyst in CH₃CN at room temperature (Table 1, Entry 1). Encouraged by this result, other solvents such as 1, 2-dichloroethane (DCE), acetone, dichloromethane (DCM) and o-dichlorobenzene (o-DCB) were tested (Table 1, Entries 2~5). It was found that 80% yield of 3a was obtained when o-DCB was used as solvent. It is worth noting that the product could also be isolated in 81% yield in the absence of catalyst (Table 1, Entry 6). Subsequently, the effect of additive on the sulfonylation reaction such as 1, 5-diazabicyclo[4.3.0]non- 5-ene (DBU), triethylamine (TEA), K₂CO₃, 4-dimethyl- aminopyridine (DMAP) were investigated (Table 1, Entries 7~10) and it was found that the yield of 3a decreased remarkably. Then the effect of light source on this reaction was investigated. It was found that 88% yield of 3a was obtained when the reaction was conducted under green LED irradiation (Table 1, Entry 11). Use of purple LED and blue LED lead to slower reaction (Table 1, Entries 12~13). If the reaction was conducted in dark, only trace of product was obtained (Table 1, Entry 14). This result showed that light irradiation was essential for this reaction.

  Table 1

  

  Table 1.  Optimization of the reaction conditions^a

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  Entry	Catalyst	Solvent	Additive	Yieldb/%
  1	NHPI	MeCN	—	59
  2	NHPI	DCE	—	43
  3	NHPI	Acetone	—	66
  4	NHPI	DCM	—	37
  5	NHPI	o-DCB	—	80
  6	—	o-DCB	—	81
  7	—	o-DCB	DBU	Trace
  8	—	o-DCB	TEA	8
  9	—	o-DCB	K2CO3	Trace
  10	—	o-DCB	DMAP	Trace
  11c	—	o-DCB	—	88
  12d	—	o-DCB	—	38
  13e	—	o-DCB	—	45
  14f	—	o-DCB	—	Trace
  a Reaction conditions: 1a (0.2 mmol), 2a (0.4 mmol), catalyst (10 mol%), solvent (1 mL), additive (0.4 mmol) under nitrogen atmosphere at room temperature using white LED (8 W) for 12 h. b Isolated yield. c Using green LEDs (8 W). d Using purple LEDs (8 W). e Using blue LEDs (8 W). f In the dark.

  Having the optimized reaction conditions in hand, the generality of this ecofriendly protocol was explored. As shown in Table 2, various sulfinic acids such as benzenesulfinic acid, 2-chlorobenzenesulfinic acid, 4-methylbenze- nesulfinic acid and 4-bromobe-nzenesulfinic acid worked well with (E)-(2-nitrovinyl)benzene, providing the desired products in 82%~90% yields (3a~3d). In particular, naphthalene-2-sulfinic acid was also effective in this reaction and the corresponding product was isolated in 75% yield (3e). These results indicated that the reactions were not sensitive to the nature of the substituent groups. On the other hand, this transformation was also applicable to various nitroolefins. Nitroolefins containing Cl, F, CH₃, CH₃O on the phenyl rings reacted smoothly with benzenesulfinic acid, giving the desired products in 78%~89% yields (3f~3k). To further investigate the scope of the reaction, the sulfonylation reactions of substituted nitroolefins and substituted sulfinic acids were investigated (3l~3u). Whether monosubstituted nitroolefins or disubstituted nitroolefins could all be transformed to the corresponding products in moderate to high yields. It is important to note that (E)-2-(2-nitrovinyl)naphthalene and (E)-2-(2-nitro- vinyl)thiophene were also suitable for this reaction and the corresponding products were isolated in moderate yields (3v~3z).

  Table 2

  

  Table 2.  Reaction Scope^abrrhzimage:30:erhhz

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  a Reaction conditions: 1 (0.2 mmol), 2 (0.4 mmol), o-DCB (1 mL), under a nitrogen atmosphere at room temperature using green LEDs (8 W).

  To clarify the mechanism of this process, radical-trap- ping reagent, 2, 2, 6, 6-tetramethyl-1-piperidinyloxy (TEM- PO) was added to the system, whereupon the reaction was completely inhibited (Scheme 2), which suggests that free-radical intermediates maybe involved in the reaction. However the exact reaction mechanism is not clear at the present stage.

  Scheme 2

  

  Scheme 2.  Control experiment

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  An on/off visible light irradiation experiment was conducted to certify the effect of light irradiation (Figure 1). The results indicated that the continuous irradiation of visible-light should be required for this reaction.

  Figure 1

  

  Figure 1.  On/off experiments

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  Base on the present results and related literatures, ^{[3o, 5, 18]} a possible reaction mechanism is proposed (Scheme 3). Initially, a sulfonyl radical is formed from sulfinic acids in the presence of visible light. Then the radical addition of sulfonyl radical and nitroolefins occurs to give benzylic radical. Finally, the products are obtained via elimination of NO₂ group.

  Scheme 3

  

  Scheme 3.  Reaction mechanism

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  In order to discover the biological activity of these desired products, several products from Table 2 were preliminarily examined for anti-microbial activity using mycelia growth inhibitory rate methods. As can be seen from Table 3 (see SI), products we tested exhibited moderate inhibitory activity against V. mali and C. glecosporioides. These results will be helpful for further research and development of pesticides.

  3.   Conclusions

  In conclusion, an eco-friendly visible light-induced approach for the synthesis of vinyl sulfones from the reaction of nitroolefins with sulfinic acid was successfully developed. Simple operation, mild reaction conditions, broad substrate scope, good yields of the desired products made this transformation have an excellent prospect. The anti-microbial activity test showed that some of the compounds had moderate inhibitory rate against V. mali and C. glecosporioides. Further work toward expanding this work and exploring reaction mechanism are underway in our laboratory.

  4.   Experimental section

  4.1   Materials

  NMR spectra were recorded on a BRUKER AVANCE Ⅲ HD 500 MHz spectrometers, operating at 500 MHz for ¹H NMR and 126 MHz for ¹³C NMR acquisitions. ¹H NMR chemical shifts (δ) are relative to TMS (δ＝0.0); chemical shifts for ¹³C NMR spectra are reported from TMS with the solvent as the internal standard. HRMS spectra were performed on an Orbitrap Fusion Lumos. All major chemicals and solvents were obtained from commercial sources and used without further purification.

  4.2   Typical procedure for the synthesis of (E)-(2- (phenylsulfonyl)vinyl)benzene

  A sealable reaction tube equipped with a magnetic stirrer bar was charged with nitrostyrene (0.2 mmol), phenyl- sulfinic acid (2.0 equiv.), and o-DCB (1 mL) under nitrogen atmosphere at room temperature using green LEDs (8 W) for 12 h. After completion, it was diluted with ethyl acetate. After the solvent was removed under reduced pressure, the residue was purified by column chromatography on silica gel to afford the corresponding product.

  (E)-(2-(Phenylsulfonyl)vinyl)benzene (3a): 42.9 mg, yield 88%. Yellow solid, m.p. 73.2~74.9 ℃ (lit.^[19] 67~68 ℃); ¹H NMR (500 MHz, CDCl₃) δ: 8.01~7.92 (m, 2H), 7.69 (d, J＝15.4 Hz, 1H), 7.61 (t, J＝7.4 Hz, 1H), 7.54 (t, J＝7.6 Hz, 2H), 7.51~7.45 (m, 2H), 7.39 (t, J＝7.5 Hz, 3H), 6.87 (d, J＝15.4 Hz, 1H); ¹³C NMR (126 MHz, CDCl₃) δ: 142.5, 140.8, 133.4, 132.4, 131.2, 129.3, 129.1, 128.6, 127.6, 127.3.

  (E)-1-Chloro-2-(styrylsulfonyl)benzene (3b): 50.2 mg, yield 90%. White solid, m.p. 182.1~183.6 ℃ (lit.^[18] 200~201 ℃); ¹H NMR (500 MHz, CDCl₃) δ: 8.23 (dd, J＝7.9, 1.5 Hz, 1H), 7.77 (d, J＝15.4 Hz, 1H), 7.53 (ddd, J＝9.6, 6.5, 1.6 Hz, 4H), 7.50~7.39 (m, 4H), 7.08 (d, J＝15.4 Hz, 1H); ¹³C NMR (126 MHz, CDCl₃) δ: 145.3, 138.2, 134.5, 132.8, 132.3, 131.9, 131.4, 130.7, 129.1, 128.7, 127.4, 125.2.

  (E)-1-Methyl-4-(styrylsulfonyl)benzene (3c): 43.8 mg, yield 85%. White solid, m.p. 118.3~119.6 ℃ (lit.^[19] 126 ℃); ¹H NMR (500 MHz, CDCl₃) δ: 7.83 (d, J＝8.3 Hz, 2H), 7.66 (d, J＝15.4 Hz, 1H), 7.48 (dd, J＝7.6, 1.8 Hz, 2H), 7.40 (dd, J＝5.8, 3.8 Hz, 3H), 7.34 (d, J＝8.0 Hz, 2H), 6.85 (d, J＝15.4 Hz, 1H), 2.44 (s, 3H); ¹³C NMR (126 MHz, CDCl₃) δ: 144.4, 141.9, 137.7, 132.4, 131.1, 129.9, 129.0, 128.5, 127.6, 21.6.

  (E)-1-Bromo-4-(styrylsulfonyl)benzene (3d): 56.0 mg, yield 87%. Yellow solid, m.p. 101.3~102.7 ℃ (lit.^[19] 103.5~104.5 ℃); ¹H NMR (500 MHz, CDCl₃) δ: 7.81 (d, J＝8.6 Hz, 2H), 7.69 (dd, J＝12.0, 3.3 Hz, 3H), 7.52~7.46 (m, 2H), 7.46~7.37 (m, 3H), 6.83 (d, J＝15.4 Hz, 1H); ¹³C NMR (126 MHz, CDCl₃) δ: 143.1, 139.8, 132.6, 132.2, 131.4, 129.2, 128.6, 126.8.

  (E)-2-(Styrylsulfonyl)naphthalene (3e): 44.6 mg, yield 76%. White solid, m.p. 132.2~133.6 ℃ (lit.^[23] 138~140 ℃); ¹H NMR (500 MHz, CDCl₃) δ: 8.55 (s, 1H), 7.99 (dd, J＝8.2, 5.1 Hz, 2H), 7.94~7.86 (m, 2H), 7.75 (d, J＝15.4 Hz, 1H), 7.69~7.59 (m, 2H), 7.52~7.46 (m, 2H), 7.43~7.34 (m, 3H), 6.92 (d, J＝15.4 Hz, 1H); ¹³C NMR (126 MHz, CDCl₃) δ: 142.5, 137.6, 135.2, 132.4, 131.2, 129.6, 129.2, 128.6, 127.9, 127.6, 127.4, 122.6.

  (E)-1-Chloro-4-(2-(phenylsulfonyl)vinyl)benzene (3f): 47.8 mg, yield 86%. White solid, m.p. 124.3~125.6 ℃ (lit.^[19] 131 ℃); ¹H NMR (500 MHz, CDCl₃) δ: 7.98~7.92 (m, 2H), 7.68~7.61 (m, 2H), 7.59~7.54 (m, 2H), 7.45~7.40 (m, 2H), 7.39~7.35 (m, 2H), 6.84 (d, J＝15.4 Hz, 1H); ¹³C NMR (126 MHz, CDCl₃) δ: 140.9, 140.5, 137.3, 133.5, 130.8, 129.7, 129.4, 127.9, 127.7.

  (E)-2, 4-Dichloro-1-(2-(phenylsulfonyl)vinyl)benzene (3g): 54.2 mg, yield 87%. White solid, m.p. 128.2~129.8 ℃ (lit.^[20] 132~133 ℃); ¹H NMR (500 MHz, CDCl₃) δ: 8.06~7.93 (m, 3H), 7.69~7.62 (m, 1H), 7.57 (t, J＝7.7 Hz, 2H), 7.49~7.41 (m, 2H), 7.26 (dt, J＝8.5, 4.2 Hz, 1H), 6.90 (d, J＝15.4 Hz, 1H); ¹³C NMR (126 MHz, CDCl₃) δ: 140.1, 137.4, 137.1, 135.9, 133.6, 130.6, 130.2, 129.4, 129.0, 127.8.

  (E)-1-Fluoro-4-(2-(phenylsulfonyl)vinyl)benzene (3h): 47.6 mg, yield 91%. Yellow solid, m.p. 103.6~105.2 ℃ (lit.^[19] 108~110 ℃); ¹H NMR (500 MHz, CDCl₃) δ: 8.01~7.91 (m, 2H), 7.70~7.60 (m, 2H), 7.55 (dd, J＝10.6, 4.7 Hz, 2H), 7.52~7.44 (m, 2H), 7.14~7.03 (m, 2H), 6.80 (d, J＝15.4 Hz, 1H); ¹³C NMR (126 MHz, CDCl₃) δ: 165.4, 163.3, 141.1, 140.6, 133.4, 130.6, 129.3, 128.6, 127.6, 127.1, 116.4, 116.2.

  (E)-1-Methyl-4-(2-(phenylsulfonyl)vinyl)benzene (3i): 43.8 mg, yield 85%. Yellow solid, m.p. 129.5~131.1 ℃ (lit.^[19] 138 ℃); ¹H NMR (500 MHz, CDCl₃) δ: 7.95 (ddd, J＝8.6, 5.3, 3.3 Hz, 2H), 7.66 (d, J＝15.4 Hz, 1H), 7.63~7.58 (m, 1H), 7.57~7.51 (m, 2H), 7.37 (d, J＝8.1 Hz, 2H), 7.19 (d, J＝8.0 Hz, 2H), 6.81 (d, J＝15.4 Hz, 1H), 2.36 (s, 3H); ¹³C NMR (126 MHz, CDCl₃) δ: 142.6, 141.9, 140.9, 133.3, 129.8, 129.6, 129.3, 128.6, 127.6, 126.0, 21.5.

  (E)-1, 2-Dimethyl-4-(2-(phenylsulfonyl)vinyl)benzene (3j): 39.7 mg, yield 73%. Yellow solid, m.p. 131.2~132.6 ℃ (lit.^[21] oil); ¹H NMR (500 MHz, CDCl₃) δ: 7.94 (d, J＝7.5 Hz, 2H), 7.62 (dd, J＝19.2, 11.4 Hz, 2H), 7.54 (t, J＝7.6 Hz, 2H), 7.27~7.20 (m, 2H), 7.14 (d, J＝7.8 Hz, 1H), 6.80 (d, J＝15.4 Hz, 1H), 2.26 (d, J＝8.9 Hz, 6H); ¹³C NMR (126 MHz, CDCl₃) δ: 142.8, 141.0, 140.6, 137.4, 133.2, 130.3, 130.0, 129.7, 129.3, 127.5, 126.3, 125.8, 19.8, 19.6.

  (E)-1-Methoxy-3-(2-(phenylsulfonyl)vinyl)benzene (3k): 44.3 mg, yield 81%. Yellow solid, m.p. 116.3~117.8 ℃ (lit.^[19] 120 ℃); ¹H NMR (500 MHz, CDCl₃) δ: 7.95 (d, J＝7.7 Hz, 2H), 7.68~7.60 (m, 2H), 7.56 (t, J＝7.8 Hz, 2H), 7.31 (t, J＝7.9 Hz, 1H), 7.08 (d, J＝7.9 Hz, 1H), 7.00~6.94 (m, 2H), 6.85 (d, J＝15.4 Hz, 1H), 3.81 (s, 3H); ¹³C NMR (126 MHz, CDCl₃) δ: 160.0, 142.4, 140.6, 133.6, 133.4, 130.1, 129.3, 127.6, 121.24, 117.1, 113.4, 55.3.

  (E)-1, 2-Dimethyl-4-(2-tosylvinyl)benzene (3l): 52.6 mg, yield 92%. Yellow solid, m.p. 92.1~93.1 ℃; ¹H NMR (500 MHz, CDCl₃) δ: 7.82 (d, J＝8.3 Hz, 2H), 7.60 (d, J＝15.4 Hz, 1H), 7.33 (d, J＝8.1 Hz, 2H), 7.25~7.19 (m, 2H), 7.14 (d, J＝7.8 Hz, 1H), 6.78 (d, J＝15.4 Hz, 1H), 2.43 (s, 3H), 2.26 (d, J＝9.5 Hz, 6H); ¹³C NMR (126 MHz, CDCl₃) δ: 144.2, 142.2, 140.4, 138.0, 137.4, 130.3, 130.1, 129.9, 129.6, 127.6, 126.2, 21.6, 19.8, 19.7. HRMS calcd for C₁₇H₁₉O₂S [M+H]⁺: 287.10977; found 287.11003.

  (E)-4-(2-((4-Bromophenyl)sulfonyl)vinyl)-1, 2-dimethyl-benzene (3m): 63.0 mg, yield 90%. Yellow solid, m.p. 103.2~105.6 ℃; ¹H NMR (500 MHz, CDCl₃) δ: 7.83~7.76 (m, 2H), 7.70~7.65 (m, 2H), 7.63 (d, J＝15.4 Hz, 1H), 7.25 (s, 1H), 7.22 (d, J＝7.8 Hz, 1H), 7.15 (d, J＝7.8 Hz, 1H), 6.76 (d, J＝15.4 Hz, 1H), 2.27 (d, J＝9.7 Hz, 6H); ¹³C NMR (126 MHz, CDCl₃) δ: 143.4, 140.8, 140.1, 137.5, 132.5, 130.4, 129.8, 129.1, 128.4, 126.3, 125.3, 19.8, 19.6. HRMS calcd for C₁₆H₁₆O₂BrS [M+H]⁺: 351.00464; found351.00489.

  (E)-4-(2-((2-Chlorophenyl)sulfonyl)vinyl)-1, 2-dimethyl-benzene (3n): 52.0 mg, yield 85%. Yellow solid, m.p. 115.2~117.6 ℃; ¹H NMR (500 MHz, CDCl₃) δ: 8.21 (d, J＝7.8 Hz, 1H), 8.21 (d, J＝7.8 Hz, 1H), 7.71 (d, J＝15.3 Hz, 1H), 7.75~7.38 (m, 4H), 7.57~7.48 (m, 2H), 7.46 (t, J＝7.4 Hz, 1H), 7.26 (d, J＝18.1 Hz, 2H), 7.16 (d, J＝7.7 Hz, 1H), 7.16 (d, J＝7.7 Hz, 1H), 7.00 (d, J＝15.3 Hz, 1H), 7.00 (d, J＝15.3 Hz, 1H), 2.28 (d, J＝7.3 Hz, 6H); ¹³C NMR (126 MHz, CDCl₃) δ: 145.6, 140.9, 138.5, 137.5, 134.3, 132.8, 131.8, 130.6, 130.4, 129.9, 127.4, 126.4, 123.7, 19.9, 19.7. HRMS calcd for C₁₆H₁₆O₂ClS [M+H]⁺: 307.05511; found 307.05540.

  (E)-1-Chloro-2-((4-methylstyryl)sulfonyl)benzene (3o): 46.7 mg, yield 80%. White solid, m.p. 180.2~182.1 ℃(dec.); ¹H NMR (500 MHz, CDCl₃) δ: 8.22 (dd, J＝7.8, 1.4 Hz, 1H), 7.74 (d, J＝15.4 Hz, 1H), 7.56~7.49 (m, 2H), 7.48~7.44 (m, 1H), 7.41 (d, J＝8.1 Hz, 2H), 7.21 (d, J＝8.0 Hz, 2H), 7.02 (d, J＝15.4 Hz, 1H), 2.38 (s, 3H); ¹³C NMR (126 MHz, CDCl₃) δ: 145.3, 142.1, 138.5, 134.3, 132.8, 131.8, 130.6, 129.8, 129.6, 128.7, 127.4, 124.1, 21.5. HRMS calcd for C₁₅H₁₄O₂ClS [M+H]⁺: 293.03946; found 293.03975.

  (E)-1-Methyl-4-((4-methylstyryl)sulfonyl)benzene (3p): 45.6 mg, yield 84%. Yellow solid, m.p. 148.9~150.2 ℃ (lit.^[19] 152~155 ℃); ¹H NMR (500 MHz, CDCl₃) δ: 7.82 (d, J＝7.9 Hz, 2H), 7.62 (d, J＝15.4 Hz, 1H), 7.35 (dd, J＝15.3, 7.9 Hz, 4H), 7.19 (d, J＝7.8 Hz, 2H), 6.79 (d, J＝15.4 Hz, 1H), 2.40 (d, J＝32.5 Hz, 6H); ¹³C NMR (126 MHz, CDCl₃) δ: 144.2, 142.0, 141.7, 137.9, 129.8, 128.5, 127.6, 126.4, 21.5.

  (E)-2-((4-Methylstyryl)sulfonyl)naphthalene (3q): 48.6 mg, yield 79%. Yellow solid, m.p. 167.6~168.3 ℃ (lit.^[22] 172 ℃); ¹H NMR (500 MHz, CDCl₃) δ: 8.54 (s, 1H), 8.03~7.95 (m, 2H), 7.93~7.84 (m, 2H), 7.71 (d, J＝15.4 Hz, 1H), 7.63 (dt, J＝14.8, 6.9 Hz, 2H), 7.38 (d, J＝8.0 Hz, 2H), 7.18 (d, J＝7.9 Hz, 2H), 6.86 (d, J＝15.4 Hz, 1H), 2.36 (s, 3H); ¹³C NMR (126 MHz, CDCl₃) δ: 142.6, 141.9, 137.7, 135.1, 132.3, 129.8, 129.6, 129.4, 129.1, 128.6, 127.9, 127.6, 126.1, 122.6, 21.5.

  (E)-1-Chloro-2-((4-fluorostyryl)sulfonyl)benzene (3r): 50.9 mg, yield 86%. Yellow solid, m.p. 119.6~122.2 ℃; ¹H NMR (500 MHz, CDCl₃) δ: 8.22 (dd, J＝7.9, 1.3 Hz, 1H), 7.73 (d, J＝15.4 Hz, 1H), 7.53 (ddd, J＝8.4, 6.2, 1.5 Hz, 4H), 7.49~7.45 (m, 1H), 7.10 (t, J＝8.5 Hz, 2H), 7.02 (d, J＝15.4 Hz, 1H). ¹³C NMR (126 MHz, CDCl₃) δ: 165.5, 163.5, 144.0, 138.1, 134.6, 132.8, 131.9, 130.8, 130.7, 130.7, 128.6, 128.6, 127.5, 125.0, 125.0, 116.5, 116.3. HRMS calcd for C₁₄H₁₁O₂ClS [M+H]⁺: 297.01437; found 297.01468.

  (E)-1-Fluoro-4-(2-tosylvinyl)benzene (3s): 46.9 mg, yield 85%. Yellow solid, m.p. 90.2~91.6 ℃ (lit.^[24] 84~85 ℃); ¹H NMR (500 MHz, CDCl₃) δ: 7.82 (d, J＝8.2 Hz, 2H), 7.62 (d, J＝15.4 Hz, 1H), 7.47 (dd, J＝8.6, 5.4 Hz, 2H), 7.35 (d, J＝8.1 Hz, 2H), 7.08 (t, J＝8.5 Hz, 2H), 6.78 (d, J＝15.4 Hz, 1H), 2.44 (s, 3H); ¹³C NMR (126 MHz, CDCl₃) δ: 165.3, 163.3, 144.5, 140.6, 137.6, 130.5, 130.0, 128.7, 127.7, 127.4, 116.4, 116.2, 21.6.

  (E)-2, 4-Dichloro-1-(2-((2-chlorophenyl)sulfonyl)vinyl)-benzene (3t): 55.3 mg, yield 80%. Yellow solid, m.p. 106.3~108.1 ℃; ¹H NMR (500 MHz, CDCl₃) δ: 8.23 (dd, J＝7.9, 1.4 Hz, 1H), 8.11 (d, J＝15.4 Hz, 1H), 7.58~7.52 (m, 2H), 7.52~7.46 (m, 3H), 7.28 (dd, J＝8.5, 2.0 Hz, 1H), 7.09 (d, J＝15.4 Hz, 1H); ¹³C NMR (126 MHz, CDCl₃) δ: 140.0, 137.8, 137.6, 136.1, 134.7, 132.9, 131.9, 130.9, 130.3, 129.4, 129.1, 128.6, 127.7, 127.5. HRMS calcd for C₁₄H₁₀O₂Cl₃S [M+H]⁺: 346.94592; found 346.94616.

  (E)-1-Chloro-4-(2-tosylvinyl)benzene (3u): 46.7 mg, yield 80%. Yellow solid, m.p. 132.6~133.7 ℃ (lit.^[19] 139~142 ℃); ¹H NMR (500 MHz, CDCl₃) δ: 7.82 (d, J＝8.3 Hz, 2H), 7.60 (d, J＝15.4 Hz, 1H), 7.41 (d, J＝8.6 Hz, 2H), 7.38~7.33 (m, 4H), 6.82 (d, J＝15.4 Hz, 1H), 2.44 (s, 3H); ¹³C NMR (126 MHz, CDCl₃) δ: 144.5, 140.4, 137.5, 137.1, 131.0, 130.0, 129.7, 129.4, 128.3, 127.8, 21.6.

  (E)-1-(2-(Phenylsulfonyl)vinyl)naphthalene (3v): 47.6 mg, yield 81%. Yellow solid, m.p. 98.2~99.5 ℃ (lit.^[23] 99~101 ℃); ¹H NMR (500 MHz, CDCl₃) δ: 8.52 (d, J＝15.2 Hz, 1H), 8.15 (d, J＝8.4 Hz, 1H), 8.01 (d, J＝7.5 Hz, 2H), 7.89 (dd, J＝17.8, 8.1 Hz, 2H), 7.59 (ddt, J＝25.6, 10.3, 7.3 Hz, 6H), 7.44 (t, J＝7.7 Hz, 1H), 6.97 (d, J＝15.2 Hz, 1H); ¹³C NMR (126 MHz, CDCl₃) δ: 140.7, 139.5, 133.7, 133.4, 131.5, 131.3, 129.6, 129.4, 128.9, 127.7, 127.3, 126.5, 125.7, 125.3, 123.0.

  (E)-1-(2-((2-Chlorophenyl)sulfonyl)vinyl)naphthalene (3w): 49.8 mg, yield 76%. Yellow solid, m.p. 136.2~138.9 ℃; ¹H NMR (500 MHz, CDCl₃) δ: 8.63 (d, J＝15.2 Hz, 1H), 8.28 (dd, J＝7.9, 1.5 Hz, 1H), 8.17 (d, J＝8.4 Hz, 1H), 7.94 (d, J＝8.2 Hz, 1H), 7.89 (d, J＝7.9 Hz, 1H), 7.72 (d, J＝7.2 Hz, 1H), 7.61 (ddd, J＝8.4, 6.9, 1.3 Hz, 1H), 7.59~7.53 (m, 3H), 7.52~7.46 (m, 2H), 7.15 (d, J＝15.2 Hz, 1H); ¹³C NMR (126 MHz, CDCl₃) δ: 142.6, 138.3, 134.6, 133.7, 132.9, 132.0, 131.7, 131.4, 130.9, 129.7, 128.9, 127.7, 127.5, 126.6, 125.9, 125.4, 123.1. HRMS calcd for C₁₈H₁₄O₂ClS [M+H]⁺: 329.03958; found 329.03975.

  (E)-1-(2-Tosylvinyl)naphthalene (3x): 47.4 mg, yield 77%. Yellow solid, m.p. 101.1~102.8 ℃ (lit.^[24]oil); ¹H NMR (500 MHz, CDCl₃) δ: 8.50 (d, J＝15.2 Hz, 1H), 8.16 (d, J＝8.4 Hz, 1H), 7.90 (dd, J＝15.7, 8.2 Hz, 4H), 7.66 (d, J＝7.2 Hz, 1H), 7.63~7.59 (m, 1H), 7.56 (dd, J＝11.0, 3.9 Hz, 1H), 7.45 (t, J＝7.7 Hz, 1H), 7.36 (d, J＝8.1 Hz, 2H), 6.95 (d, J＝15.2 Hz, 1H), 2.44 (s, 3H); ¹³C NMR (126 MHz, CDCl₃) δ: 144.4, 139.0, 137.6, 133.6, 131.3, 130.0, 129.6, 128.8, 127.8, 127.3, 126.5, 125.6, 125.3, 123.0, 21.6.

  (E)-2-(2-(Phenylsulfonyl)vinyl)thiophene (3y): 39.5 mg, yield 79%. Yellow solid, m.p. 95.6~97.1 ℃ (lit.^[19] 93~94 ℃); ¹H NMR (500 MHz, CDCl₃) δ: 8.01~7.91 (m, 2H), 7.80 (d, J＝15.1 Hz, 1H), 7.55 (t, J＝7.6 Hz, 2H), 7.44 (d, J＝5.0 Hz, 1H), 7.32 (d, J＝3.4 Hz, 1H), 7.07 (dd, J＝5.0, 3.7 Hz, 1H), 6.65 (d, J＝15.1 Hz, 1H); ¹³C NMR (126 MHz, CDCl₃) δ: 140.8, 136.9, 135.1, 133.3, 132.5, 130.0, 129.3, 128.3, 127.6, 125.4.

  (E)-2-(2-(Phenylsulfonyl)vinyl)furan (3z): 36.5 mg, yield 78%. Yellow solid, m.p. 105.8~106.6 ℃ (lit. oil^[25]); ¹H NMR (500 MHz, CDCl₃) δ: 7.99~7.90 (m, 2H), 7.61 (d, J＝7.4 Hz, 1H), 7.54 (t, J＝7.6 Hz, 2H), 7.46 (dd, J＝18.3, 8.2 Hz, 2H), 6.73 (dd, J＝18.7, 9.2 Hz, 2H), 6.49 (dd, J＝3.4, 1.8 Hz, 1H); ¹³C NMR (126 MHz, CDCl₃) δ: 148.7, 145.6, 140.8, 133.3, 129.3, 128.9, 127.5, 124.7, 116.9, 112.6.

  Supporting Information   Full experimental details and NMR spectra for compounds 3a~3z. The Supporting Information is available free of charge via the Internet at http://sioc-journal.cn/.

  
  
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• 

  Scheme 1  Synthesis of vinyl sulfones

  下载: 全尺寸图片 幻灯片
  

  Scheme 2  Control experiment

  下载: 全尺寸图片 幻灯片
  

  Figure 1  On/off experiments

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  Scheme 3  Reaction mechanism

  下载: 全尺寸图片 幻灯片

  Table 1.  Optimization of the reaction conditions^a

  Entry	Catalyst	Solvent	Additive	Yieldb/%
  1	NHPI	MeCN	—	59
  2	NHPI	DCE	—	43
  3	NHPI	Acetone	—	66
  4	NHPI	DCM	—	37
  5	NHPI	o-DCB	—	80
  6	—	o-DCB	—	81
  7	—	o-DCB	DBU	Trace
  8	—	o-DCB	TEA	8
  9	—	o-DCB	K2CO3	Trace
  10	—	o-DCB	DMAP	Trace
  11c	—	o-DCB	—	88
  12d	—	o-DCB	—	38
  13e	—	o-DCB	—	45
  14f	—	o-DCB	—	Trace
  a Reaction conditions: 1a (0.2 mmol), 2a (0.4 mmol), catalyst (10 mol%), solvent (1 mL), additive (0.4 mmol) under nitrogen atmosphere at room temperature using white LED (8 W) for 12 h. b Isolated yield. c Using green LEDs (8 W). d Using purple LEDs (8 W). e Using blue LEDs (8 W). f In the dark.

  下载: 导出CSV

  Table 2.  Reaction Scope^abrrhzimage:30:erhhz

  a Reaction conditions: 1 (0.2 mmol), 2 (0.4 mmol), o-DCB (1 mL), under a nitrogen atmosphere at room temperature using green LEDs (8 W).

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•