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 α-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, SO2Tol and P(O)Ph2, previously delicate nitrogen substituents such as phenyl or benzhydryl are tolerated. The same protocol also allows the unprecedented addition to representative ketone-derived imines.