Catalytic Nitrile Hydroboration: A Route to N,N-Diborylamines and Uses Thereof.

Catalytic reduction of nitriles is considered as an attractive and atom-economical route to a diversity of synthetically valuable primary amines. Compared to other methods, dihydroboration approach has been developed relatively recently but has already attracted the attention of many research groups due to reasonably mild reaction conditions, selectivity control and the access to N,N-diborylamines, which emerged as powerful reagents for C-N bond forming reactions. Early developments in catalytic dihydroboration of nitriles implied precious metal catalysts along with harsh conditions and prolonged reaction times, whereas recent advances mostly rely on base and main group metal catalytic systems with significantly improved profiles. This minireview aims to provide an overview of advances and challenges of dihydroboration of nitriles with d-, f- and main group metal catalysts. Mechanistic features of different catalytic systems, functional group tolerance and scope of the methods are also presented. The synthetic utility of N,N-diborylamies, beyond simple protodeborylation, is discussed in the aspect of N-arylation, imine and amide synthesis.