Electrochemical Synthesis of 4-Sulfenylisocoumarins via Radical Cascade Annulation of o-Alkynylbenzoates with Thiophenols

doi:10.6023/cjoc202508022

Chinese Journal of Organic Chemistry ›› 2026, Vol. 46 ›› Issue (3): 1039-1049.DOI: 10.6023/cjoc202508022 Previous Articles Next Articles

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电化学促进邻炔基苯甲酸酯与硫酚的自由基串联环化反应合成4-硫代异香豆素

马超^a, 徐晓玲^a, 骆翔^a, 鲁瑞娟^a, 虞国棋^b^,^*(), 蔡涛^a^,^b^,^*()

^a 绍兴文理学院化学化工学院浙江绍兴 312000
^b 浙江省脂溶性维生素工程中心浙江绍兴 312000

收稿日期:2025-08-25 修回日期:2025-10-15 发布日期:2025-11-27
通讯作者: 虞国棋, 蔡涛
基金资助:
绍兴市基础公益项目(2023A11003); 绍兴文理学院科研基金(2023LG003)

Electrochemical Synthesis of 4-Sulfenylisocoumarins via Radical Cascade Annulation of o-Alkynylbenzoates with Thiophenols

Chao Ma^a, Xiaoling Xu^a, Xiang Luo^a, Ruijuan Lu^a, Guoqi Yu^b^,^*(), Tao Cai^a^,^b^,^*()

^a College of Chemistry and Chemical Engineering, Shaoxing University, Shaoxing, Zhejiang 312000
^b Zhejiang Engineering Research Center of Fat-Soluble Vitamin, Shaoxing University, Shaoxing, Zhejiang 312000

Received:2025-08-25 Revised:2025-10-15 Published:2025-11-27
Contact: Guoqi Yu, Tao Cai
Supported by:
Shaoxing Basic Public Welfare Project(2023A11003); Research Project of Shaoxing University(2023LG003)

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Abstract

The first electrochemical method that employs commercially available, stable, and inexpensive thiophenols as sulfenylating agents for the efficient synthesis of valuable 4-sulfenylisocoumarins is presented. Various thiophenols containing both electron-donating and electron-withdrawing groups reacted smoothly with o-alkynylbenzoates to afford the corresponding 4-sulfenylisocoumarins in moderate to good yields. Preliminary mechanistic investigation, including controlled experiments and cyclic voltammetry (CV) experiments, indicated that this electrochemical cyclization might proceed via a radical pathway. In comparison to existing methods, this strategy circumvents the need for moisture-sensitive and pre-functionalized sulfenylating reagents, such as aryl sulfenyl chloride (ArSCl), diaryl disulfide (ArSSAr) and N-thiosuccinimide, significantly broadens the substrate scope, and offers a practical and sustainable alternative for the synthesis of 4-sulfenylisocoumarins.

Key words: 4-sulfenylisocoumarin, thiophenol, o-alkynylbenzoate, electrochemical synthesis, radical cascade annulation

Cite this article

Chao Ma, Xiaoling Xu, Xiang Luo, Ruijuan Lu, Guoqi Yu, Tao Cai. Electrochemical Synthesis of 4-Sulfenylisocoumarins via Radical Cascade Annulation of o-Alkynylbenzoates with Thiophenols[J]. Chinese Journal of Organic Chemistry, 2026, 46(3): 1039-1049.

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References 11

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Entry	Electrode (＋/－)	Electrolyte	Solvent	Yield^b/%
1	Pt/Pt	Bu₄NBF₄	CH₃CN	Trace
2	GF/Pt	Bu₄NBF₄	CH₃CN	24
3	RVC/Pt	Bu₄NBF₄	CH₃CN	12
4	Carbon rod/Pt	Bu₄NBF₄	CH₃CN	25
5	C100/Pt	Bu₄NBF₄	CH₃CN	45
6	C200/Pt	Bu₄NBF₄	CH₃CN	70
7	C200/C100	Bu₄NBF₄	CH₃CN	46
8	C100/C100	Bu₄NBF₄	CH₃CN	14
9	C200/Pt	Bu₄NBF₄	THF	Trace
10	C200/Pt	Bu₄NBF₄	HFIP	20
11	C200/Pt	Bu₄NBF₄	EtOH	0
12	C200/Pt	Bu₄NBF₄	Acetone	25
13	C200/Pt	Bu₄NBF₄	DMSO	0
14	C200/Pt	Bu₄NBF₄	CH₃CN/acetone (V∶V=10∶1)	45
15	C200/Pt	Bu₄NBF₄	CH₃CN/H₂O (V∶V=10∶1)	38
16	C200/Pt	Bu₄NBF₄	CH₃CN/HFIP (V∶V=10∶1)	82
17	C200/Pt	Bu₄NClO₄	CH₃CN/HFIP (V∶V=10∶1)	24
18	C200/Pt	Bu₄NPF₆	CH₃CN/HFIP (V∶V=10∶1)	15
19	C200/Pt	Bu₄NBr	CH₃CN/HFIP (V∶V=10∶1)	Trace
20	C200/Pt	CF₃SO₃Li	CH₃CN/HFIP (V∶V=10∶1)	30
21	C200/Pt	LiClO₄	CH₃CN/HFIP (V∶V=10∶1)	66
22^c	C200/Pt	Bu₄NBF₄	CH₃CN/HFIP (V∶V=10∶1)	70
23^d	C200/Pt	Bu₄NBF₄	CH₃CN/HFIP (V∶V=10∶1)	80
24^e	C200/Pt	Bu₄NBF₄	CH₃CN/HFIP (V∶V=10∶1)	48

Entry	Electrode (＋/－)	Electrolyte	Solvent	Yield^b/%
1	Pt/Pt	Bu₄NBF₄	CH₃CN	Trace
2	GF/Pt	Bu₄NBF₄	CH₃CN	24
3	RVC/Pt	Bu₄NBF₄	CH₃CN	12
4	Carbon rod/Pt	Bu₄NBF₄	CH₃CN	25
5	C100/Pt	Bu₄NBF₄	CH₃CN	45
6	C200/Pt	Bu₄NBF₄	CH₃CN	70
7	C200/C100	Bu₄NBF₄	CH₃CN	46
8	C100/C100	Bu₄NBF₄	CH₃CN	14
9	C200/Pt	Bu₄NBF₄	THF	Trace
10	C200/Pt	Bu₄NBF₄	HFIP	20
11	C200/Pt	Bu₄NBF₄	EtOH	0
12	C200/Pt	Bu₄NBF₄	Acetone	25
13	C200/Pt	Bu₄NBF₄	DMSO	0
14	C200/Pt	Bu₄NBF₄	CH₃CN/acetone (V∶V=10∶1)	45
15	C200/Pt	Bu₄NBF₄	CH₃CN/H₂O (V∶V=10∶1)	38
16	C200/Pt	Bu₄NBF₄	CH₃CN/HFIP (V∶V=10∶1)	82
17	C200/Pt	Bu₄NClO₄	CH₃CN/HFIP (V∶V=10∶1)	24
18	C200/Pt	Bu₄NPF₆	CH₃CN/HFIP (V∶V=10∶1)	15
19	C200/Pt	Bu₄NBr	CH₃CN/HFIP (V∶V=10∶1)	Trace
20	C200/Pt	CF₃SO₃Li	CH₃CN/HFIP (V∶V=10∶1)	30
21	C200/Pt	LiClO₄	CH₃CN/HFIP (V∶V=10∶1)	66
22^c	C200/Pt	Bu₄NBF₄	CH₃CN/HFIP (V∶V=10∶1)	70
23^d	C200/Pt	Bu₄NBF₄	CH₃CN/HFIP (V∶V=10∶1)	80
24^e	C200/Pt	Bu₄NBF₄	CH₃CN/HFIP (V∶V=10∶1)	48

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电化学促进邻炔基苯甲酸酯与硫酚的自由基串联环化反应合成4-硫代异香豆素

Electrochemical Synthesis of 4-Sulfenylisocoumarins via Radical Cascade Annulation of o-Alkynylbenzoates with Thiophenols

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