Chemical and Electrochemical Reduction of Pyrido-as-triazines

Article abstract of DOI:10.1021/jo00336a026

The catalytic hydrogenation of 3-phenylpyrido<3,2-e>-as-triazine (1) and of 3-phenylpyrido<3,4-e>-as-triazine (2) leads to the corresponding 1,4-dihydro derivatives 3c and 4c.The structures of these compounds were established by 1H NMR using the nuclear Overhauser effect and long-range coupling constants.Reduction by LiAlH4 gives the 5,6,7,8-tetrahydro derivative of 1 and the 4,5,6,10-tetrahydro derivative of 2; the conformation of the latter compound has been established.In aqueous methanol, 1 and 2 are electrochemically reduced into 3c and 4c, respectively; the same products are obtained in acetonitrile in the presence of phenol.The electrochemical reduction of 2 in acetonitrile in the presence of acetic anhydride leads to a mixture of 1,4-diacetyl-1,4-dihydro and 1,2-diacetyl-1,2-dihydro compounds.These results are compared with those obtained in the reduction of other azanaphthalenes.