Using Alcohols As Simple H2-Equivalents for Copper-Catalysed Transfer Hydrogenations

Catalytic transfer hydrogenations are among the most practical synthetic methods for the selective reduction of functional groups. Cheap and readily available dihydrogen (H2) equivalents are highly desirable for catalytic transfer hydrogenations, as inevitably, waste is generated by the formal H2 source. Copper hydride catalysis generally relies on stoichiometric use of waste-generating hydrosilanes. Here, we demonstrate that simple alcohols can be employed as H2 equivalents in stereoselective alkyne semihydrogenations, prototypical copper hydride-catalysed transformations.