Oxidative Conversion of Sulfonyl Indoles into 3-Alkylidene-2-oxindoles under Flow Chemical Conditions

Abstract

Sulfonyl indoles were converted into 3-alkylidene-2-oxindoles using NCS as the sole reagent under flow chemical conditions. The conjugated oxindole derivatives were generally obtained as E stereoisomers in moderate to satisfactory yields. The transformation entails the oxidation of the indole ring by NCS followed by elimination of arylsulfinic acid in order to install the exocyclic unsaturation.

Key words

flow chemistry - 2-oxindoles - heterocycles - indoles - oxidation

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