Enol ester: A Versatile Synthetic Equivalent for Isocoumarin and Chromone Synthesis

Abstract

Oxygen counterpart of enamide, called as “Enol ester”, is abundant in various biological active natural products, and hence considered as an important structural motif with immense attention. Enol esters also involved in different reactions such as cycloadditions, Aldol reactions, Mannich type reactions, and asymmetric hydrogenation reactions to afford synthetically useful products. Considering the versatile applications of enol esters, several methods have been appeared in the literature for their synthesis. On the other hand, synthetic applications of enol esters in oxygen-containing heterocycle synthesis is relatively less literature precedent. Therefore, a work has been initiated to employ the enol ester as an important structural scaffold to assemble biologically potent oxygen-containing heterocycles. The present thesis entitled “Enol ester: A Versatile Synthetic Equivalent for Isocoumarin and Chromone Synthesis” involves the base-mediated synthesis of enol esters from the reaction of aromatic carboxylic acid and propiolic esters as well as 1,3-dicarbonyl compounds, and the utilization of the so formed enol esters in flavonoid synthesis. Additionally, silver-catalyst was exploited for the first time in the formation of Csp2−Csp3 bond to assemble isocoumarin and chromone motif under mild reaction conditions.