The reaction between azo-compounds and trialkylboranes

Abstract

trans-Azobenzene does not react with organoboranes, but cis-azobenzene, prepared separately or in situ by irradiation, reacts essentially instantaneously, undergoing hydroboration according to equation (i). cis- PhNNPh R₃B [graphic omitted] + R′(–H)(i)

The reaction involves cis-elimination of the olefin, and probably follows a cyclic six-centre mechanism.

Dialkyl trans-azodicarboxylates react in the same way [equation (iia)], but the trans-hydroboration is now accompanied by homolytic alkylboration of the unsaturated systems according to equation (iib). trans- RO₂CNNCO₂R + R′₃B[graphic omitted]