Cu(I)-catalyzed oxidative cyclization of alkynyl oxiranes and oxetanes

Abstract : In the presence of a Cu(I) catalyst and a pyridine oxide, alkynyl oxiranes and oxetanes can be converted into functionalized five- or six-membered a,ß-unsaturated lactones or dihydrofuranaldehydes. This new oxidative cyclization is proposed to proceed via an unusual allenyloxypyridinium intermediate. © 2011 American Chemical Society.