Stereoselective synthesis of donor-acceptor substituted cyclopropafuranones by intramolecular cyclopropanation of vinylogous carbonates: Divergent synthesis of tetrahydrofuran-3-one, tetrahydropyran-3-one, and lactones

"Chemical Equation Presented" A new, highly stereoselective Intramolecular cyclopropanation of vlnylogous carbonate with carbenes using copper catalyst is described. Each of the cyclopropane bonds of these two acceptor substituted cyclopropafuranones can be cleaved with complete regiocontrol by judicious choice of reaction conditions, leading to a diverse array of frameworks such as tetrahydrofuran-3-one, tetrahydropyran-3-one, and lactones. © 2009 American Chemical Society.