Base-mediated carboxylation of unprotected indole derivatives with carbon dioxide

Abstract

A simple and straightforward method for the preparation of indole-3-carboxylic acids was discovered through the direct carboxylation of indoles with atmospheric pressure of carbon dioxide (CO 2) under basic conditions. The key for the reaction was found to be the use of a large excess of LiO tBu as a base to suppress the undesired decarboxylation side reaction. © 2012 American Chemical Society.