1,4-Reduction of α,β-unsaturated ketones catalyzed by tetraarylhydrophosphoranes

We demonstrate that a pentavalent phosphorous compound,
tetraarylhydrophosphorane, is capable of catalyzing 1,4-reduction of
α,β-unsaturated ketones in the presence of pinacolborane. The structure
and properties of tetraarylhydrophosphorane and its participation in the
chemoselective 1,4-reduction were elucidated through both experimental and
theoretical approaches.