Photochemistry of homoconjugated ketones: 2-(carbomethoxy)spiro[5.5]undeca-1, 3-dien-7-one.

Abstract The direct and sensitized irradiation of the title compound ( 2 c) was studied with particular attention to its oxa-di-π-methane rearrangement, the product of which is of notable structural and synthetic interest. X-ray diffraction data of the final product (8) are given to support structural assignments.