Intramolecular reactions of N-nitrenes: oxidation of 3-amino-2-(2,4-dimethoxyphenylbutyl)quinazolin-4(3H)-ones

Abstract

The N-nitrenes generated by oxidation of N-aminoquinazolones (1) and (2) are trapped by the remote 2,4-dimethoxyphenyl ring. Oxidation of (1) in benzene gives the metacyclophane (3) in 60% isolated yield whereas oxidation in methanol gives (5), (6) and (8). The structures of the acetal (5) and the imine (8) have been confirmed by X-ray crystallography. Oxidation of (2) in methanol yields (11) and (16). An explanation is offered for the selectivity for attack on the 2,3- or 5,6-double bonds of the dimethoxyphenyl ring by the N-nitrene derived from (1).