Abstract
The reaction of 3-(3H)-iiminoquinazolin-4-one derivatives 4a-c with 2-spiro-1,3-oxathio-Ian-5-one derivatives 7a-f in ethanol yielded 3-[3′(2′-spirothiazolidin-4′-one)Jquinazolin-4-one derivatives 8a-r in excellent yield. Cyclization of compounds 8a-r with sodium hydroxide in ethanol or with fusion with anhydrous sodium acetate gave the spirothiazolopyrazoloquinazolinone derivatives 9a-r. All the synthesized spiro heterocyclic derivatives were identified by conventional methods (IR.
1
H NMR) and elemental analyses.