Intramolecular amidation:: synthesis of novel imidazo[2,1-b][1,3,4]thiadiazole and imidazo[2,1-b][1,3]thiazole fused diazepinones

Novel heterocyclic systems 2-alkyl/aryl-9-(2-hydroxybenzylidene)-7,9-dihydro-8H-[1,3,4]thiadiazolo[2',3':2,3]imidazo[4,5-( [1,2]diazepin-8-one and 9-(2-hydroxy-benzylideile)-3,3-dimethyl-3,4,7,9-tetrahydro-2H-11-thia4b,6,7,10-tetriazaindeno[1,2-a]azulene-1,8-dione are synthesized via an intramolecular annidation reaction. An interesting ring opening and cyclization of 2-alkyl/aryl-6-(2-oxo-2H-chromen-3-yl)imidazo[2, 1-b][1,3,4]thiadiazole-5-carbaldehydc and 6,6-dimethyl-8-oxo-2-(2-oxo-2H-chromen-3-yl)-5,6,7,8-tetrahydromidazo[2,1-b][1,3]benzothiazole-3-carbaldehyde are discussed. (c) 2006 Elsevier Ltd. All rights reserved.