Synthesis of Sulfonated Oxindoles by Potassium Iodide Catalyzed Arylsulfonylation of Activated Alkenes with Sulfonylhydrazides in Water

Abstract

A catalytic system consisting of KI, 18-crown-6, and TBHP for arylsulfonylation of activated alkenes with sulfonylhydrazides as sulfonyl precursor is described. This protocol provides a practical and environmentally benign method for the construction of sulfonated oxindoles in water.

Sulfonyl Hydrazides in Organic Synthesis: A Review of Recent Studies

“…One important synthetic application of highly reactive sulfonyl radicals was their use in the intramolecular cyzlization or cyzlization/rearrangement cascade (Eq. 13‐1).…”

Synthesis of Oxindoles through Silver‐Catalyzed Trifluoromethylation–, Difluoromethylation– and Arylsulfonylation–Cyclization Reaction of N‐Arylacrylamides

“…Later, Li and Duan independently reported the oxidative benzylation‐cyclization reaction of N ‐arylacrylamides to form alkyl‐substituted oxindoles through a tandem radical addition/cyclization reaction 23. Very recently, metal‐free radical acetylation,24a sulfonylation,24b azidolation,24c and hydroxylalkylation24d of N ‐arylacrylamides were also reported to deliver various functionalized oxindoles. As for the synthesis of trifluoromethyl containing oxindoles, in 2012, Liu reported a Pd‐catalyzed trifluoromethylation‐cyclization of N ‐arylacrylamides by using TMSCF 3 as the trifluoromethyl group source under mild conditions (Scheme , a) 25a.…”

Recent advances in sulfur- and phosphorous-centered radical reactions for the formation of S–C and P–C bonds

“…Li and Xu group reported iodide-catalyzed formation of sulfonyl radical from sulfonyl hydrazides for the reactions of N-phenylmethacrylamides 187 for the synthesis of tosylated oxindoles 188 using water as a solvent (Scheme 85) 148. The Wang group developed a free reaction for the synthesis of sulfonated oxindoles 189 through the direct arylsulfonylation of N-phenylmethacrylamides with sulfinic acids (fragmentation of sulfonyl radical led to highly stereoselective synthesis ofcyclopentanes 191 bearing four stereogenic centers (Scheme 87).…”