Palladium-catalyzed asymmetric annulation between aryl iodides and racemic epoxides using a chiral norbornene cocatalyst

Org Chem Front. 2018 Nov 7;5(21):3108-3112. doi: 10.1039/c8qo00808f. Epub 2018 Sep 25.

Abstract

Herein, we describe our initial development of an asymmetric Pd-catalyzed annulation between aryl iodides and racemic epoxides for synthesis of 2,3-dihydrobenzofurans using a chiral norbornene cocatalyst. A series of enantiopure ester-, amide- and imide-substituted norbornenes have been prepared with a reliable synthetic route. Promising enantioselectivity (42-45% ee) has been observed using the isopropyl ester-substituted norbornene (N1*) and the amide-substituted norbornene (N7*).