EFFICIENT SOLID STATE PHOTOCYCLIZATION OF STERICALLY CONGESTED α-o-TOLYL KETONES DESPITE "POOR" GEOMETRIES FOR HYDROGEN ABSTRACTION

Article abstract of DOI:10.1016/S0040-4039(01)80575-X

Several α-mesityl and α-(o-tolyl)acetophenones undergo photocyclization to 2-indanols almost quantitatively when irradiated as crystals, even those that undergo significant competing α-cleavage or 1,3-aryl shift in solution.The requisite triplet δ-hydrogen abstraction apparently can occur at what appears to be a "bad" geometry.One ketone, α-(o-tolyl)propiophenone, partially rearranges to the β-isomer, which arises from disproportionation of the radicals formed by initial α-cleavage.