A new highly asymmetric chelation-controlled heck arylation.
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 alpha-carbon. A chelated pi-intermediate is proposed to explain the excellent chiral induction.
Nilsson
Peter
P
Department of Organic Pharmaceutical Chemistry, Uppsala Biomedical Centre, Uppsala University, Sweden.
Larhed
Mats
M
Hallberg
Anders
A