Reactions between nitrile oxides and carbenium ions: synthesis of benzoxazines, oximes and amides through intramolecular ortho and ipso attack

Reactions between nitrile oxides and benzylic carbocations are described. Different results were obtained when the carbocations were generated from the corresponding chlorides with different Lewis acids, with addition products such as benzoxazines, oximes, and amides being produced. Primary, secondary, and tertiary carbocations showed different reactivities. The product ratios strongly depended on the substituents on the aromatic ring of the benzylic carbocations. Evidence for the proposed mechanism is reported.