Enantioselective N-Alkylation of Indoles via an Intermolecular Aza-Wacker-Type Reaction.

The development of an intermolecular and enantioselective aza-Wacker reaction is described. Using indoles as the N-source and a selection of alkenols as the coupling partners selective ß-hydride elimination toward the alcohol was achieved. This strategy preserves the newly formed stereocenter by preventing the formation of traditionally observed enamine products. Allylic and homoallylic alcohols with a variety of functional groups are compatible with the reaction in high enantioselectivity. Isotopic-labeling experiments support a syn amino-palladation mechanism for this new class of aza-Wacker reactions.

Diastereo- and enantioselective phase-transfer alkylation of 3-substituted oxindoles with racemic secondary alkyl halides.

A catalytic asymmetric alkylation of fully substituted enolates with racemic, non-activated secondary alkyl halides is described. The chiral 1,2,3-triazolium ion enables excellent diastereo- and enantiocontrol via enantiofacial discrimination of prochiral enolates and kinetic resolution of secondary halides.