A New and simple synthesis of 2‐aryl‐4,9‐dihydrocyclohepta[<i>b</i>]pyran‐4,9‐diones

Abstract

Abstract 3‐Acetyltropolone ( 1 ) reacted with 2‐methoxybenzaldehyde ( 2a ) in the presence of ethyl orthoformate and perchloric acid to afford 2‐(2‐methoxyphenyl)‐4,9‐dihydrocyclohepta[ b ]pyran‐4,9‐dione ( 3a ). The reactions with 3,4‐dimethoxybenzaldehyde ( 2b ), vanillin ( 2c ), and piperonal ( 2d ) gave respectively the corresponding products 3b‐d . The reaction with benzaldehyde ( 2e ) gave uncyclized 3‐cinnamoyltropolone ( 4 ).