ELECTRON-TRANSFER VS NUCLEOPHILIC-ADDITION OF KETENE SILYL ACETALS WITH HALOGENATED P-BENZOQUINONE DERIVATIVES

A beta,beta-dimethyl-substituted ketene silyl acetal reduces p-chloranil to produce the carbon-oxygen adduct, the hydrolysis of which yields the corresponding hydro-quinone ether (3). The structure of 3 has been determined by the X-ray crystal analysis. On the other hand, the reaction of a nonsubstituted ketene silyl acetal with p-fluoranil yields the carbon-carbon adduct selectively. The mechanistic difference between the C-O and C-C bond formation is elucidated based on the kinetic study.