N-oxides in the quinoxaline series

Acyl derivatives of 2-aminoquinoxaline and their 1-N -oxides, as well as methyl derivatives of some of those compounds, are synthesized. IR spectra of these compounds in the solid state, and UV spectra of their solutions, showed that, with respect to the ability of its 2-acylamino derivatives to tautomerize to the imido form, quinoxaline is close to pyrimidine, and below quinoline and pyridine. With respect to the amideimide tautomerism equilibrium position, N-oxides of 2-acylaminoquinoxalines differ little from acylamides of quinoxaline themselves. The action of benzene sulfochloride on 2-aminoquinoxaline-1-N-oxide in pyridine below 0°leads to deoxidation of the N O group, and introduction of the benzene sulfonyloxy group at position 3 in the quinoxaline ring.For Part VIII see [17].