Development of new synthetic reagents in Mitsunobu-type reaction

The author's work in the past 10 years have been reviewed, focusing on their endeavor to find more effective and versatile reagents applicable to the Mitsunobu-type reactions. The project was originally planned to provide various N-alkyl-N-allylacylamides, the substrates for the aza-Claisen rearrangement the authors have developed. The effort was rewarded by more colorful results than expected originally, introducing to the chemical community two new series of reagents, that is, azodicarboxamides, such as TMAD and DHTD, and phosphoranes, such as CMBP and CMMP. The former series mediates the Mitsunobu reaction between primary alcohols and various protonic acids (N- and C-nucleophiles) of pKa up to 12, while the later, though needed a higher temperature, mediates the reactions of both primary and secondary alcohols with protonic acids of pKa of up to 23.5. Utilizing both the aza-Claisen rearrangement and new Mitsunobu reaction, a variety of natural products including isoirridomyrmecin, alpha -skytanthine, antimycin A(3b) as well as various alkaloids and pheromones were synthesized in reasonable ease.