Chemoselective Hydroboration of Isocyanates Catalyzed by Commercially Available NaH

A simple, efficient, and economical method for the chemoselective hydroboration of isocyanates is reported. Commercially available NaH, at very low loadings, efficiently catalyzes the selective conversion of isocyanates to N-boryl formamides, bis(boryl)hemiaminals, and N-boryl methyl amines. NaH catalyzes isocyanates to controllably open the N=C bond to build an amide bond, and can also remove the C=O bond to obtain N-boryl methyl amines. Both aliphatic and aromatic isocyanates can be quantitatively converted to the corresponding hydroboration products. Furthermore, there is excellent functional group selectivity over imines, nitriles, and olefins. Additionally, through in situ monitoring, a possible reaction mechanism is proposed. And the chemical intermediates generated by NaH and HBpin are responsible for all the reduction steps.