The wittig reaction of benzofuran-2,3-diones.

Abstract

The Wittig reaction of benzofuran-2, 3-diones (2), cyclic α-ketoesters, was examined. The reaction of 2 having an electron-donating substituent on the aromatic ring with a stable ylide afforded not 3-alkylidene-2(3H)-benzofuranones (4) but 2-alkylidene-3(2H)-benzofuranones (1) with high regioselectivity.