Studies on bisthiazolo[3,2-a:4′,5′-d]pyrimidine derivatives. Part II

Abstract

Ethyl 4-allylthioureido-3-aryl-2-imino-4-thiazoline-5-carboxylates (V), obtained by condensation of ethyl 4-amino-3-aryl-2-imino-4-thiazoline-5-carboxylates (I) with allyl isothiocyanate, were converted into 9H-3-aryl-6,7-dihydro-6-methylbisthiazolo[3,2-a:4′,5′-d]pyrimidine-2(3H),9-diones (IX) when heated in polyphosphoric acid. Treatment of compounds (V) with bromine, followed by dehydrobromination, gave ethyl 3-aryl-4-(5-bromomethylthiazolidin-2-ylideneamino)-2-imino-4-thiazoline-5-carboxylates (XI), which were cyclised to 9H-3-aryl-6-bromomethyl-6,7-dihydrobisthiazolo[3,2-a:4′,5′-d]pyrimidine-2(3H),9-diones (XII).