Synthetic applications of α-hydroxydiazenes. III. Uncatalyzed and phenol catalyzed hydroalkylation of alkenes and of azobenzene with alkylazodiphenylmethanols

Alkylazodiphenylmethanols (C 6 H 5 ) 2 C(OH)N = NR, (R = CH(CH 3 ) 2 , CH 2 CH 3 , CH 3 ), when decomposed in the presence of olefinic substrates or in the presence of azobenzene, hydroalkylate those substrates. Addition of R and H across the double bond of an unsymmetric alkene occurs with the regiochemistry expected for a radical mechanism, in which the group R adds first. Radical intermediates from decomposition of alkylazodiphenylmethanols have been demonstrated earlier with spin trapping experiments. The fact that addition of phenol can enhance the yield of hydroalkylation product suggests that the process is a radical chain reaction, with chain carrying steps consisting of the reactions: One deuterioalkylation and some yield-optimizing experiments are also reported.