Unexpected conversion of 2-aminophenylacetic acid hexafluorosilicate to 2-oxindol under mild conditions

Abstract

Fluoride therapy is known to be the most effective and safe method of caries treatment. In recent years, ammonium hexafluorosilicates, including salts with biologically active cations, have been actively studied as promising anticaries agents. Considering the literature data, significant pharmacological potential is expected for aminoacids hexafluorosilicates. Previously we have carried out the synthesis of 2-, 3-, 4-aminophenylacetic acids hexafluorosilicates (2-, 3-, 4-APhHFS), an attempt to recrystallize them from ethanol led to the formation of a red crystalline product in the case of 2-APhHFS. The purpose of this work is to determine the composition and structure of the 2-APhHFS recrystallization product.