Enantioselective Friedel-Crafts Alkylations of Pyrroles and Indoles via α′-Hydroxyenones

Significance

The Friedel-Crafts reaction is of great value in organic synthesis. In terms of metal-catalyzed Friedel-Crafts alkylations, there are few examples demonstrating high enantioselectivity. In many of the reported cases, strongly coordinating bidentate Michael acceptors are required for good enantiocontrol. Presented herein, non-enolizable α′-hydroxyenones represent the above characteristics and, in the presence of easily accessible tert-butyl-bis(oxazoline) Cu(II) complexes and electron-rich heteroaromatics, provide highly enantioenriched Friedel-Crafts alkylation products. This method is efficient with both pyrrole and indole as nucleophile, and with alkyl or aryl β-substituents.