New Type of Oxidation-Reduction Condensation

Thioetherification and azidation of tertiary alcohols by a new type of oxidation-reduction condensation using phenoxydiphenylphosphine (= phenyl diphenylphosphinite, 1) and azide compounds are reported by Mukaiyama and Kuroda’s group. These reactions proceed under mild and neutral conditions. Chiral secondary and the tertiary alcohols having an α-ester group are converted into the corresponding chiral sulfides and azides with inversion of the configuration.

When DEAD is employed as an oxidizing agent, condensation of tertiary alcohols and 2-nitrobenzoic acid affords the corresponding ester with inversion of the configuration.

These new types of oxidation - reduction condensations using 1 are applicable to sterically-hindered tertiary alcohols whereas the Mitsunobu reaction (PPh₃-DEAD) is not.