New heterocycles derived from 2-aminothiophenol

Abstract

2-Aminothiophenol reacted with β-propiolactone in ethanol to give β-[o- (β-carboxyethylamino)phenylthio]propionic acid (1) which underwent cyclodehydration in polyphosphoric acid to give derivatives of two new heterocyclic ring systems, viz., 1,8-dioxo-1,2,3,4,5,6,7,8-octahydro-4- thia-5-azaphenanthrene (2) and 4,8-dioxo-3,4,7,8-tetrahydro-2H,6H- [1,4]thiazepino[2,3,4-ij]quinoline (3). Analytical and spectral data are presented which support the structures proposed for these compounds.     Alternative synthesis of each heterocycle was achieved by using media other than polyphosphoric acid to cyclize the dicarboxylic acid (1). Phosphoryl chloride gave β-(4-oxo-2,3,4,5-tetrahydro-1,5- benzothiazepin-5-yl)propionic acid (4), which was cylodehydrated smoothly to the thiazepine (3). Concentrated sulphuric acid afforded β- (4-oxo-1,2,3,4-tetrahydroquinol-8-ylthio)propionic acid (6) which was converted into the thiazaphenanthrene (2) by polyphosphoric acid.     Bromination reactions and reduction with sodium borohydride of the thiazepine (3) are also described.