Silyl Radicals. XV. Stereochemical Course of Chlorine Abstraction by 1-Methyl-4-t-butyl-1-silacyclohexyl Radicals from Polychloroalkane

The isomerically pure cis and trans 1-methyl-4-t-butyl-1-silacyclohexane were subjected to the free radical chlorination with carbon tetrachloride in the presence of a catalytic amount of benzoyl peroxide under UV irradiation at 0 °C, affording the corresponding chlorosilanes with retention of configuration. With less reactive polyhalocarbons, however, less stereospecific products were obtained. A mechanism that inversion of silyl radicals competes with chlorine abstraction is proposed. Relative rates of each reaction were analyzed with a steadystate assumption.