Enabling Reductive C-N Cross-Coupling of Nitroalkanes and Boronic Acids by Steric Design of P(III)/P(V)═O Catalysts.

An organophosphorus-catalyzed C-N bond-forming reductive coupling of nitroalkanes with arylboronic acids and esters is reported. The method shows excellent chemoselectivity for the nitro/boronic acid substrate pair, allowing the synthesis of N-(hetero)arylamines rich in functionalization. The identification of a sterically reduced phosphetane catalyst capable of productive coupling in the P(III)/P(V)═O redox manifold is the key enabling development. Combined experimental kinetics and computational mechanistic studies show that the sterically reduced catalyst affects post-rate-limiting steps to enable the C-N coupling event in preference to deleterious side-paths.