High Degree of Chemoselectivities Recorded during the Reformatsky Reaction on Coumarinyl phenyl ketones and Formyl Coumarins.

Abstract

Bromo-zinc enolate reagents showed excellent chemo-selectivity towards 7-methoxy-8- coumarinyl phenyl ketones (1, 2) furnished α- alkylidene chromene derivatives (5-10) together with bridged- lactone (11), cinnamate derivative (12) & γ-benzopyran(13). In case of 7-methoxy-8-formylcoumarin (3,4) afforded β-hydroxy ester (14,16) and α-β- unsaturated esters(15,17-21) showing excellent chemoselectivity with E-configuration.