Synthesis of the Disubstituted Maleic Anhydride Frame Using a Novel Tandem Radical-Polar Reaction

Abstract

An unreported 5-endo-trig atom-transfer radical cyclization of cyclic N-α-dichloroacyl-ketene-N,S-acetals, which evolves as a tandem radical-polar process, is described. The reaction, which is carried out in the presence of a Cu(I) complex catalyst (10 mol%) and an inorganic base (i.e., carbonate), can be exploited as the key step for a novel, short, and versatile synthesis of the 3,4-disubstituted maleic anhydride nucleus.