This account deals with an overview of the development of catalytic addition reactions of carbonyl compounds to alkynes catalyzed by a variety of indium salts. The new C-C bond formation reactions provide a powerful tool for alpha-functionalization of carbonyl compounds, including direct alpha-vinylation with acetylene, regioselective alpha-alkenylation, and alpha-ynenylation that can be applied to a modular synthesis of alpha-arylated beta-keto esters.