3-Hydroxy-3-((3-methyl-4-nitroisoxazol-5-yl)methyl)indolin-2-one as a versatile intermediate for retro-Henry and Friedel–Crafts alkylation reactions in aqueous medium

Abstract

The first example of a retro-Henry type reaction is reported using 3-hydroxy-3-((3-methyl-4-nitroisoxazol-5-yl)methyl)indolin-2-ones which are prepared via catalyst-free Henry reaction of 3,5-dimethyl-4-nitroisoxazole and isatin. These compounds were used for the selective synthesis of 3-hydroxy-indolyl-2-oxindoles and bis-indolyl-2-oxindoles (symmetric/unsymmetric) via retro-Henry type reaction followed by Friedel–Crafts alkylation reactions in water (one-pot approach). 3-Hydroxy-3-((3-methyl-4-nitroisoxazol-5-yl)methyl)indolin-2-ones on hydrolysis yielded 2-(3-hydroxy-2-oxoindolin-3-yl)acetic acids, which are sources of natural products and biologically active compounds.