Synthesis of Esters via Sodium Carbonate Promoted Oxa-Michael Addition of Acids to α,β-Unsaturated Ketones

Abstract

Ester bonds are found widely in various fine chemicals, medicines, pesticides and functional materials. Despite the apparent simplicity, the construction of ester bonds often constitutes the most challenge in the synthesis of complex molecular containing ester functionality. Oxa-Michael addition represents an important class of organic reactions in carbon-heteroatom bond formation. The use of alcohol donors in oxa-Michael additions is well known. However, the use of carboxylic acid as the donor in the reaction is difficult due to the low activity of acid and a more pronounced reversibility of the reaction. To date, there is no general oxa-Michael addition of acids to α,β-unsaturated ketones reported. Herein, an efficient sodium carbonate promoted oxa-Michael addition of acids to α,β-unsaturated ketones to synthesize esters is reported. With a broad substrate scope, a well-common catalyst and simple operation, the approach provides a facile, practicable, economical, and environmentally benign method for the synthesis of esters.