Electrooxidative Metal‐Free Dehydrogenative α‐Sulfonylation of 1H‐Indole with Sodium Sulfinates

Abstract

A method for the electrochemical α‐sulfonylation of 1H‐indole with arenesulfinates was developed. A variety of indoles underwent this sulfonylation smoothly at room temperature under metal‐free and chemical‐oxidant‐free conditions to afford indolyl aryl sulfones in good to high yields. This reaction was found to tolerate a variety of functional groups, including halides and cyclopropyl, ether, ester, and aldehyde groups. It was applied to the synthesis of biologically active 5‐HT6 modulators.

Direct Metal‐ and Reagent‐Free Sulfonylation of Phenols with Sodium Sulfinates by Electrosynthesis

“…Therefore the electrochemical mode of operation provides a safe and sustainable manner of organic synthesis in general, and also especially for producing aryl sulfones . A recent example was presented by Feng et al . By an iodide‐mediated potentiostatic electrolysis, a sulfonylation of 1 H ‐indoles with sodium sulfinates was performed.…”

Electrochemical Oxidative C−H Sulfonylation of Anilines

“…In 2015, Yuan and co‐workers developed a electrochemical oxidative sulfonylation of olefins with sodium sulfinates. Soon after, Waldvogel, Yu and Nematollahi– reported related works, respectively. Considering the significance of this type of reaction, we conceived that C−H sulfonylation of anilines could be achieved via an electrochemical oxidative C−S bond formation.…”

Electrocatalytic Oxidative Transformation of Organic Acids for Carbon–Heteroatom and Sulfur–Heteroatom Bond Formation

“…Electrogeneration of phenoquinone and its analogues as electrophiles is a popular strategy for the arylation of sulfinic acids . Additionally, in 2017, Yu and co‐workers reported the electrochemical α‐sulfonylation of 1 H ‐indoles with sodium sulfinates by using a catalytic amount of TBAI . Because reviews by the groups of Baran and Waldvogel summarized part of this field, herein we only focus on some representative advances made in recent years and do not reiterate the same content.…”

“…[50] Additionally,i n2 017, Yu and coworkers reported the electrochemical a-sulfonylation of 1H-indoles with sodium sulfinates by using ac atalytic amount of TBAI. [51] Because reviews by the groups of Baran and Waldvogel summarized part of this field, [1a, b] herein we only focus on some representative advancesm ade in recent years and do not reiterate the same content.N otably,f or some cases, not only CÀSb onds, but also SÀNb onds, are constructed in sequential reactions. We discuss these cases in Section5.3.…”