Moisture-Assisted Hydroboration of Nitriles and Conversion Thereof to N-Heterocyles and N-Containing Derivatives

The recent revelation of hidden-borane catalysis has revolutionized the field of catalytic hydroboration in organic synthesis. Many nucleophilic reaction promoters, previously believed to be the catalysts, in fact primarily facilitated the formation of borane (BH3), which subsequently acted as the true catalyst. This revelation prompted us to explore the untapped potential of these unexpected transformations, with a view to simplify hydroboration using more cost-effective and environmentally friendly nucleophilic pre-catalysts. Via computational studies, we were able to identify that water can actually undertake that role. Herein, we report a study on simple hydroboration of nitriles, a notorious-ly challenging yet synthetically valuable class of substrates, using nothing more than moisture as an activating agent. This moisture-assisted nitrile hydroboration process can seamlessly integrate with a range of downstream transfor-mations in a one-pot fashion to produce valuable N-containing products such as symmetrical imines, thioureas and bis(alcohol)amines as well as N-heterocyclic derivatives such as pyrroles, pyridines, pyridinium salts, 2-iminothiazolines and carbazoles.