Lewis Acid Mediated Reactions of 1-Cyclopropyl-2-arylethanones with Allenic Esters:  A Facile Synthetic Protocol for the Preparation of Dihydrofuro[2,3-<i>h</i>]chromen-2-one Derivatives

2007-09-27T00:00:00Z (GMT) by Min Shi Xiang-Ying Tang Yong-Hua Yang
TMSOTf-mediated reactions of 1-cyclopropyl-2-arylethanones with allenic esters afford a novel method for the synthesis of dihydrofuro[2,3-<i>h</i>]chromen-2-one derivatives in moderate to good yields. This process is a sequential reaction involving a nucleophilic ring-opening reaction of the cyclopropane by H<sub>2</sub>O, two intermolecular aldol-type reactions and one intramolecular aldol-type reaction, a cyclic transesterification, dehydration, and aromatization mediated by Lewis acid.