The reactivity of the high-energy intermediates formed in the reactions of Group 13 metal atoms and aromatic alkenes

Group 13 metal atoms were reacted with aromatic alkenes in a specialized metal atom reactor known as a "rotating cryostat." The nature of the intermediates formed was deduced from a GC-MS study of their hydrolysis and deuterolysis products. The product studies suggest that 2-phenylaluminacyclopropane, cis- and trans-3,4-diphenylaluminacyclopentane, and cis- and trans- 2,4-diphenylaluminacyclopentane are formed when Al atoms react with styrene, and 2-methyl-2-phenylaluminacyclopropane and 3,4-dimethyl- 3,4-diphenylaluminacyclopentane are formed when Al atoms react with α -methylstyrene. These findings are consistent with the radicals detected in the EPR spectroscopic studies of Al-alkene reaction mixtures prepared under similar conditions. Mechanisms for the formation of the organoaluminium intermediates are discussed. Analogous organogallium intermediates are formed when gallium atoms react with styrene. The reductive coupling of styrene did not occur when In and Tl atoms were used. Only trace quantities of phenylethane were detected in the hydrolyzed reaction mixture.Key words: Group 13 metal atoms, aluminium atoms, organoaluminium intermediates, metal atom reactions.