Cobalt-catalyzed alkyne-nitrile cyclotrimerization to form pyridines in aqueous solution.

A new, water-soluble cobalt(I) catalyst has been used in the aqueous, chemospecific, cyclotrimerization of one nitrile with two alkynes for the synthesis of highly functionalized pyridines. Several different functional groups are well incorporated in this transformation, including unprotected alcohols, ketones, and amines. Double isotopic crossover data, as well as nitrile dependence on the rate of product formation, suggest associative rate-determining coordination of the nitrile.