Highly Regioselective Copper-Catalyzed cis- and trans-1-Propenyl Grignard Cleavage of Hindered Epoxides. Application in Propionate Synthesis
journal contributionposted on 21.07.2006, 00:00 authored by David Rodríguez, Marlenne Mulero, José A. Prieto
Hindered protected and unprotected epoxy alcohols were regioselectively cleaved using copper-catalyzed cis- and trans-1-propenylmagnesium bromide. The reaction exhibited good yield and excellent regioselectivity in systems where organocuprates and organoalanes failed. The cis Grignard reagent displayed no double-bond isomerization, whereas the trans isomer showed partial trans-to-cis equilibration, which was minimized by controlling the reagent formation conditions. The reaction was shown to be highly useful for the elaboration of the C10−C15 Streptovaricin D ansa chain fragment.