Enantioselective alkylations of tributyltin enolates catalyzed by Cr(salen)CI: Access to enantiomerically enriched all-carbon quaternary centers

The catalytic asymmetric α-alkylation of tributyltin enolates with a range of primary alkyl halides is catalyzed by a chiral Cr(salen) complex. The reaction constitutes the first transition-metal-catalyzed system for α-alkylation of carbonyl substrates with this important class of electrophiles, providing access to five-, six-, and seven-membered ring ketone products bearing α-quaternary stereocenters in high enantioselectivity and synthetically useful yields.