A New Highly Asymmetric Chelation-Controlled Heck Arylation

Abstract
This communication describes the development of a new highly asymmetric chelation-controlled Heck arylation. The methodology permits formation of 2-aryl-2-methyl cyclopentanones in good to very good two-step yields (45−78%) with excellent chiral enrichment (90−98% ee). In contrast to the well-known direct coupling to the enolate of a cyclic ketone, the Heck arylation of the corresponding N-methyl pyrrolidin enol ether requires neither a strong base nor a blocking of the alternative nonalkylated α-carbon. A chelated π-intermediate is proposed to explain the excellent chiral induction.