Activation of the Si-B Linkage: Copper-Catalyzed Addition of Nucleophilic Silicon to Imines

Activation of the Si-B bond through copper-catalyzed transmetalation quickly developed into a practical method to generate Cu-Si reagents. These silicon nucleophiles cleanly add to aldehyde-derived imine electrophiles to form alpha-silylated amines in protic media, and no carbon-to-nitrogen Brook-type rearrangement of the intermediate anion is observed. Aside from electron-withdrawing groups at the imine nitrogen atom, for example, SO(2)Tol and P(O)Ph-2, previously delicate nitrogen substituents such as phenyl or benzhydryl are tolerated. The same protocol also allows the unprecedented addition to representative ketone-derived imines.