Process for preparing indoline-2-carboxylic acids via alpha-hydroxy-2-nitrobenzenepropanoic acid

Abstract

Disclosed herein is a process for obtaining indoline-2-carboxylic acid (or derivatives thereof) comprising the following steps: (a) reducing .alpha.-oxo-2-nitrobenzenepropanoic acid to .alpha.-hydroxy-2-nitrobenzenepropanoic acid, (b) replacing the hydroxyl group of the latter with a chlorine atom utilizing a selected Vilsmeier chlorinating reagent at temperatures of at least 20.degree. C., (c) reducing the nitro group of the resulting .alpha.-chloro-2-nitrobenzenepropanoic acid to obtain .alpha.-chloro-2-aminobenzenepropanoic acid, and (d) cyclizing the latter in aqueous base to form the desired indoline-2-carboxylic acid. Alternately, steps (c) and (d) may be combined in a one pot step by using, for example, a Raney nickel-hydrazine reducing medium.

Dependencies are inferred from the claim text.