Iodine–PPh3-mediated C3-sulfenylation of indoles with sodium sulfinates

Abstract

3-(Alkylsulfanyl)-and 3-(arylsulfanyl)indoles were efficiently prepared by the reaction of indoles with sodium sulfinates mediated by iodine-PPh 3 in ethanol. The salient features of the present protocol are simplicity, high efficiency, non-anhydrous conditions, environmentally friendly reagents and solvent, and short reaction time.

Sulfenylation of C–H Bonds for C–S Bond Formation under Metal‐Free Conditions

“…For example, 1 equiv. of I 2 was used to promote the sulfenylation of indole in the absence of an oxidant …”

“…of I 2 was used to promote the sulfenylation of indole in the absence of an oxidant. [41] Imidazo heterocycles could also be sulfenylated by sodium sulfinates in the presence of triphenylphosphine (Scheme 33). With I 2 as catalyst, various desired products were synthesized in moderate to high yields.…”

Sustainable and Site‐Selective C−H Sulfenylation of Aromatic Compounds with Thiol using Catalytic Graphene Oxide and NaI

“…The incorporation of sulfenyl groups into heterocyclic moieties like indole has garnered much attention because of their wide uses. Among the various indole derivatives, 3‐sulfenylindoles are significant owing to their potential uses as drugs for the treatment of cancer, heart diseases, allergies, HIV and Alzheimer′s disease (Figure ) . Because of their synthetic importance and diverse pharmacological activities, synthesis of aryl sulfanes represents an important chemical reaction in organic chemistry.…”

“…Considering the toxicity as well as a high cost of various transition‐metal‐based catalysts, metal‐free approaches have also been developed. The most common is to use iodine in the presence of thiol, or other sulfur‐based reagents like disulfide, sulfinate, sulfonyl chloride, sulfonyl hydrazide . However, most of these conditions using thiols require the presence of an oxidant, such as tert ‐butyl hydroperoxide (TBHP), hydrogen peroxide (H 2 O 2 ), or DMSO –.…”

Recent Advances in the C(sp2)-S Bond Formation Reactions by Transition Metal-Free C(sp2)-H Functionalization

“…Scheme 12). 随后, Kuhakarn 等[33] 使用相对更加简单的 I 2 /PhPh 3 催化体系, 在乙醇为溶剂 80 ℃的加热条件下, 也顺利实现了这一 同时释放出 HI. 次碘酸和 HI 之间的氧化还原反应 重新生成分子点进行催化(Scheme 13).…”