A Stereospecific Synthesis of Azo Nitriles

Article abstract of DOI:10.1021/jo00389a047

A series of α,α'-dicyanoazoalkanes 2 have been prepared in high isolated yield (96-98percent) by treatment of the corresponding α,α'-dichloroazoalkanes 3 (generated from ketazines 1) with trimethyl cyanide and 50 molpercent stannic chloride at low temperature.Usa of 5 mol percent stannic chloride resulted in the formation of α-chloro-α'-cyanoazoalkanes 4.Single-crystal X-ray diffraction analysis of α,α'-dichloro-3,3,3',3'-tetramethyl-2,2'-azobutane (3a) and the 2-chloro-2'-cyano (4a) and the 2,2'-dicyano (2a) derivatives established that all three have the same relative configuration and thus the complete stereospecifity of the cyanation.The utility of the reaction was demonstrated by the successful synthesis of (2S,2'R,4S,4'S)-2,2'-dimethyl-4,4'-diphenyl-2,2'-azopentanenitrile (11, X = CN).