Development of New Mitsunobu Reagents.

The Mitsunobu reaction, a popular alkylation reaction utilizing the redox system between diethyl azodicarboxylate and triphenylphosphine, has a shortcoming that it can only be applied satisfactorily to a nucleophile (HA) of pKa less than 11. In order to overcome the limitation, we introduced several combinations of azodicarboxamides (TIPA, ADDP, TMAD, and DHTD) and tributylphosphine. In our continual search for new versatile reagents, we found cyanomethylenetrialkylphosphorane (CMBP, CMMP) was capable of mediating the alkylation of various HA of larger pKa than 11. Utilizing these reagents, the efficient alkylation of N-, C-, and O-nucleophiles, such as tosylamides, active methylene compounds, alcohols, and carboxylic acid was accomplished. The results are presented along with their synthetic application.