Copper(II)-Catalyzed Selective Hydroboration of Ketones and Aldehydes

A novel nonanuclear copper(II) complex obtained by a facile one-pot self-assembly was found to catalyze the hydroboration of ketones and aldehydes with the absence of an activator under mild, solvent-free conditions. The catalyst is air- and moisture-stable, displaying high efficiency (1980 h–1 turnover frequency, TOF) and chemoselectivity on aldehydes over ketones and ketones over imines. This represents a rare example of divalent copper catalyst for the hydroboration of carbonyls.