α-C-H bond of carboxylic acids, amides, esters and other synthons can be triggered in the absence or presence of a transition metal catalyst under oxidative conditions. While transition metal free conditions predominantly employ electrophilic heteroatom coupling agents and proceeds via enolate chemistry, nucleophilic coupling partners are introduced at the α-position of aliphatic acid derivatives by means of umpolung approaches. However, the hurdle remains in the enolization process owing to the high pKa value of α-C(sp3)-H bonds of carboxylic acid derivatives (pKa >20). Herein, we have uncovered a new approach to the enhancement of the degree of enolization of α-C-H bond of aliphatic carboxylate equivalents that leads to α–chalcogenation via ion pair catalysis (scheme 1). On the other hand, we have introduced new protocols that allow the α-functionalization of aliphatic carboxylic acids by transforming them into the corresponding alkyl-benzazoles.

α-C(sp3)–H bonds adjacent to the benzazole ring in the 2-alkyl side chain are rather activated by the azole ring presumably due to rapid tautomerization of these systems thereby expediting the required metal catalyzed functionalization process. Relying on this strategy, we have achieved various C–C and C–heteroatom bond forming reactions giving expedient access to α-methoxylated (C–O), α-aminated (C–NHAr), α-cyanomethylenated aliphatic carboxylic acids via benzazole intermediates (scheme 1).