AN EFFICIENT APPROACH TO THE IMIDAZO[5,1-c][1,4]BENZOTHIAZINE SKELETON. A NOVEL TRICYCLIC RING SYSTEM

Abstract

Derivatives of a new type tricyclic system having a 1,4-benzothiazine skeleton are described. The reaction of l-(2-mercaptophenyl)-2//-imidazol-2-ones 2 with excess formaldehyde in acid medium resulted in the formation of 2,4-dihydro-lH-imidazo[5,l-c][l,4]benzothiazin-l-one 3. The starting compounds 2 were prepared by a modification of a previously described method of ring transformation of 3-(2-oxopropyI)-2(3//)-benzothiazoIones in reactions with primary amines.