Modification of Photochemical Reactivity by Cyclodextrin Complexation: Alteration of Photochemical Behavior via Restriction of Translational and Rotational Motions. Alkyldeoxybenzoins

Article abstract of DOI:10.1021/jo00234a005

The photochemical behavior of alkyldeoxybenzoins has been investigated in isotropic organic solvents, in aqueous cyclodextrin solutions, and when they are bound to cyclodextrin in the solid state.Norrish type I and type II reactions occur in these media and the product distributions resulting from these primary processes are dependent on the medium.While in organic solvents the type I and the type II products are obtained in equal amounts, in the aqueous cyclodextrin solution the type II products are formed in large excess.In the solid state the type II products constitute more than 90percent of the product distribution.Ratios of products resulting via elimination and cyclization from the type II 1,4-diradical are also altered by the host cyclodextrin.Conformational and super-cage effects have been invoked to rationalize the dramatic alteration of the photobehavior of alkyldeoxybenzoins by the cyclodextrin.