2,6‐Diaryl‐4,4‐disubstituted‐4<i>H</i>‐thiopyran: Source for spiro heterocycles

Abstract

Abstract The 1,5‐diaryl‐3,3‐disubstituted‐1,5‐pentanedione on reaction with ammonium acetate, phosphorus pentoxide and phosphorus pentasulfide gave respective 1,4‐dihydropyridine, 4 H ‐pyran and 4 H ‐thiopyran. Novel spiro heterocycles have been obtained by the cyclocondensation of 4 H ‐thiopyran with hydrazine, hydroxylamine, urea and thiourea.