Synthesis and Cyclization of 3-Cinnamoyltropolones

Abstract

Alkaline condensation of 3-acetyltropolone (1) with benzaldehydes gave 3-cinnamoyltropolones (2 a-d), which were cyclized with concentrated orthophosphoric acid to afford 2-aryl-2, 3, 4, 9-tetra-hydrocyclohepta [b] pyran-4, 9-diones (3a-d) and oxidized with selenium dioxide to give 2-aryl-4, 9- dihydrocyclohepta [b] pyran-4, 9-diones (4a-d).