Palladium-catalyzed cascade ring expansion reaction of 1-(3-methoxycarbonyloxy-1-propynyl)cyclobutanols with phenols

A palladium-catalyzed transformation of 1-(3-methoxycarbonyloxy-1-propynyl)cyclobutanols to cyclo-pentanones on treatment with phenol derivatives is described. This process can be visualized to proceed via nucleophilic attack to allenyl palladium species by phenol, followed by ring expansion reaction of π-allylpalladium complex to form the corresponding cyclopentanone.