Thiation of Oxindoles

Abstract

The thiation of methyl substituted oxindoles (I) with phosphorous pentasulfide gave the corresponding 2-indolinethiones (II). The 2-indolinethione (II) having more than one hydrogen at 3-position, however, were sensitive towards phosphorous pentasulfide to produce the indolic compounds such as III, IV, V and VI. On the other hand the 2-indolinethione (VIII) prepared from VII with phosphorous pentasulfide, was stable towards the reagent. Reactivity of 2-indolinthione (IIb) was compared with the oxindole (Ib) in some reactions including the deuteration at 3-position in deuterochloroform-acetic acid-d₄.