Tsunoda et al. developed a widely-used variant where two reagents in the reaction are replaced by a single (cyanomethylene)trialkylphosphorane reagent with ylide character.
Shing and coworkers found recently that a variant of this reaction could be used to C-alkylate monosubstituted derivatives of Meldrum's acid, where a resonance-delocalized ester enolate reacts with the phosphonium salt intermediate present in the mechanism. Tsunoda et al. developed a widely-used variant where two reagents in the reaction are replaced by a single (cyanomethylene)trialkylphosphorane reagent with ylide character. Another common variant uses hydrazoic acid as the nucleophile. In the true mechanism of this reaction, triphenylphosphine attacks a compound containing a nitrogen-nitrogen double bond, forming a betaine intermediate which is protonated and then reacts with an alcohol to form a phosphonium salt. This intermediate is captured by the carboxylate nucleophile to yield triphenylphosphine oxide and an ester with an inversion of alcohol stereochemistry. FTP, name this reaction, known for using the reagent diethyl azodicarboxylate, or DEAD, developed by and named for a Japanese chemist.
Shing and coworkers found recently that a variant of this reaction could be used to C-alkylate monosubstituted derivatives of Meldrum's acid, where a resonance-delocalized ester enolate reacts with the phosphonium salt intermediate present in the mechanism.
Mitsunobu Reaction