Boron Catalysis in the Transformation of Carboxylic Acids and Carboxylic Acid Derivatives

Carboxylic acids, amides, and esters are ubiquitous motifs in functional organic molecules. However, the reactivities of these high oxidation state carbonyl compounds are far lower than ketones and aldehydes, and catalysts applicable to transform this class of carbonyl compounds are limited. On the other hand, boron catalysts have found various applications in the transformation of carbonyl compounds by taking advantage of the unique properties derived from their vacant p-orbitals. The continuous advancement of boron catalysis has realized several unprecedented direct transformations of carboxylic acids, amides, and esters in the past decade. In this review, representative achievements of boron catalysis are summarized according to reaction types by focusing on their applications to non-activated carboxylic acids, amides, and esters.