Journal of the American Chemical Society, Vol.120, No.46, 11904-11911, 1998
Structure and reactivity of vinylcyclopropane radical cation : Electron transfer photochemistry and ab initio calculations
The electron-transfer photochemistry of vinylcyclopropane (1) generates three ring-opened products, 2-4, each bearing a methoxy as well as a 4-cyanophenyl group. The products are ascribed to nucleophilic attack of methanol on the radical cation, 1(.+). The attack is regioselective but not regiospecific; attack at the secondary cyclopropane carbons, leading to 2 and trans-3, is preferred; attack at the terminal vinylic carbon, yielding trans-4, occurs to a lesser extent. The potential surface of 1(.+) was probed by ab initio calculations; 1(.+) has two minima, anti- and syn-1(.+); both have C-s symmetry and belong to the unusual structure type with two lengthened cyclopropane bonds. The calculations are in general agreement with the observed reaction pattern.
Keywords:NUCLEOPHILE-OLEFIN COMBINATION, DENSITY-FUNCTIONAL THEORY;PHOTO-NOCAS REACTION, X-RAY GEOMETRIES, AROMATIC-SUBSTITUTIONREACTION, HYPERFINE COUPLING-CONSTANTS, FROZEN FREON MATRICES;GAS-PHASE, THERMAL TRANSFORMATIONS, SATURATED-HYDROCARBONS