Taniguchi (Kanazawa Univ.)
et al. have reported a new catalytic Mitsunobu reaction with ethyl 2-(4-cyanophenyl)hydrazinecarboxylate [
E1299] (10 mol%) under atmospheric oxidation conditions. They describe the catalytic system in which ethyl 2-arylazocarboxylate, an oxidized azo form of
E1299, plays a role as diethyl azodicarboxylate (DEAD). The azo compound-promoted Mitsunobu reactions of alcohols with carboxylic acids in the presence of triphenylphosphine successfully proceed to give ester products. Then, generated
E1299 is reoxidized to its azo form by
in situ iron catalyzed atmospheric oxidation.
E1299 provides good results with nucleophiles other than carboxylic acids. On the other hand,
E0998 is suitable for the reactions with carboxylic acids.