Enantioselective Catalyst Systems from Copper(II) Triflate and BINOL-Silanediol.

Silanediol and copper catalysis are merged, for the first time, to create an enhanced Lewis acid catalyst system for enantioselective heterocycle functionalization. The promise of this silanediol and copper catalyst combination is demonstrated in the enantioselective addition of indoles to alkylidene malonates to give rise to the desirable adducts in excellent yield and high enantiomeric excess. From these studies, 1,1'-bi-2-naphthol (BINOL)-based silanediols emerge as one-of-a-kind cocatalysts. Their potential role in the reaction pathway is also discussed.