Synthesis of some new spiro(pyran-4,2'-benzoxazole) derivatives

Article abstract of DOI:10.1055/s-1994-25425

Ketene S,S-acetal 2 reacts with 2-aminophenol to afford 2-(1-acetyl-2- oxopropylidene)benzoxazole (3) which was allowed to react with a variety of active methylenes having an α-cyano or α-keto group to give spiro[pyran- 4,2'-benzoxazole] derivatives 5-12. Compound 3 also reacts with bromomalononitrile to afford spiro[3,3-diacetyl-2,2-dicyanocyclopropane- 1,2'-benzoxazole] 13 through a nucleophilic addition and cyclization.