Access to chromone-3-carboxylic acid via silver mediated coupling of 4-hydroxy coumarin and enol ester

A silver-mediated aerobic approach to access 2-methyl-chromone-3-carboxylic acid from the reaction of 4-hydroxy coumarin and enol ester in the presence of base has been presented. Mechanistic investigation suggests that the base induced Michael-type addition reaction of 4-hydroxy coumarin to the enol ester resulting the sequential ring opening and closing with the liberation of acetone are the key-steps for the overall transformation. Theoretical calculation of energy of the intermediates by DFT supports the proposed reaction mechanism. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

A silver-catalyzed aerobic approach has been developed for the synthesis of 2-methyl-chromone-3-carboxylic acid from the reaction of 4-hydroxy coumarin and enol ester in the presence of base. Mechanistic investigation suggests that the key steps for the overall transformation include the base induced Michael-type addition reaction and sequential ring opening and closing with the liberation of acetone. Theoretical calculation of energy of the intermediates by DFT supports the proposed reaction mechanism.