Catalyst-Free Diborylation and Silaboration of Azoarenes: A Simple Photoinduced Approach.

The diborylation of the N=N double bond of azoarenes has been achieved using a commercially available diboron reagent, Bcat [bis(catecholato)diboron]. By utilizing the photo-switchable nature of azoarenes under blue-LED light irradiation, an uncatalyzed diborylation and silaboration yielded a broad range of functionalized hydrazine derivatives. The mechanistic origin validates the importance of cis configuration, which is corroborated by theoretical calculations.