Synthesis and structure of α-azo-2-ketomethylquinolines

Sixteen α-phenylazo compounds derived from 2-ketomethylquinolines and two of their N-methyl derivatives were prepared. The structure of these compounds were studied using IR, UV, Mass, 1H NMR and 13C NMR spectroscopies, which revealed that all of the compounds exist exclusively in their azo form (A). Quantum mechanical PM3 computations were also carried out on the tautomers of two representative compounds to explain their relative stabilities and structures.