Cyclobutanes in organic synthesis. Part I. Fragmentation to 1,4-dicarbonyl compounds. General considerations

Abstract

Photo-cycloaddition of vinyl acetates to 2-cyclohexenones followed by hydrolysis of the acetate group and by oxidative fragmentation leads to 2-alkyl-2-cyclohexenones in which the newly introduced alkyl group bears a 2′-carbonyl group. A similar, less generally applicable method, involving photo-cycloaddition, bromination, and heterolytic fragmentation is also described. Possible applications of this sequence in organic synthesis are discussed.