Synthesis and cyclization of 3-[3 '(2 '-spirothiazolidin-4 '-onyl)] quinazolin-4-one derivatives

The reaction of 3-(3H)-aminoquinazolin-4-one derivatives 4a-c with 2-spiro- 1,3-oxathio-lan-5-one derivatives 7a-f in ethanol yielded 3-[3'(2'-spirothi azolidin-4'-one)]quinazolin-4-one derivatives 8a-r in excellent yield. Cycl ization of compounds 8a-r with sodium hydroxide in ethanol or with fusion w ith anhydrous sodium acetate gave the spirothiazol-opyrazoloquinazolinone d erivatives 9a-r. All the synthesized spiro heterocyclic derivatives were id entified by conventional methods (IR. H-1 NMR) and elemental analyses.