Transition-Metal-Catalyzed Rearrangement of 1,1-(Oligomethylene)-4-aryl-2-butene-1,4-diols: Ring Expansion vs. Aryl Group Migration

Abstract

The transition-metal-catalyzed rearrangement of 1,1-(oligomethylene)-4-aryl-2-butene-1,4-diols was investigated. In the presence of PdCl(2)(MeCN)(2) and Cu(OTf)(2), a rapidly equilibrating 1,3-isomerization is followed by 1,2-migration to produce cyclopentanones or cyclohexanones through expansion Of four- or five-membered ring systems. When employing larger ring systems or acyclic cores, aryl migration provides 2-aryl aldehydes.