Regioselective Ortho Lithiation of 3-Aryl and 3-Styryl Furans

Abstract

[structure: see text]. An unusual regioselectivity pattern for the ortho lithiation of 3-aryl and 3-styryl furans has been uncovered wherein lithiation occurs preferentially at the sterically encumbered 2-position. The results are attributed, at least in part, to stabilization of the intermediate furyl anion by through-space donation of pi-electron density from the substituent appended at the 3-position to the lithium cation. This ortho lithiation reaction may be applied as a useful synthetic tool for accessing 2,3-disubstituted furans.