Condensation Op 3-Acetyl-and 3-Acetyl-4-Methyl-2H-1-Benzopyran-2-One with Aromatic Adehydes

Abstract

The reactivities of 3-acetyl-2H-1-benzo-pyran-2-one (2) and 3-acetyl-4-methyl-2H-1-benzopy-ran-2-one (3)are compared in the condensation with aromatic aldehydes. It is established that the benzopyrones 2 and 4 condense with various aromatic aldehydes in chloroform containing some drops of piperidine by boiling for 7 hours and azeotropic distillation of water, yielding 3-cinnamoyl-2H-1-benzopyran-2-ones (3a-g) and 4-(2-arylvinyl)-3-acetyl-2H-1-benzopyran-2-ones (6a-f), respectively. Evidence is provided that benzopyrone 4 participates in the condensation with the methyl group in position 4. A probable mechanism of the process is proposed.