Non-innocent pyridyl nitrogens: unprecedented interconversion of N-bridgehead-thiadiazolium salts and thiatriazine in the generation of thiatriazinyl.

ABSTRACT

Condensation of N-2-pyridylimidoyl-2-pyridylamidine with S2Cl2 affords fused N-bridgehead-1,2,5-thiadiazolium salts, which can be converted to 3,5-bis(2-pyridyl)-4-hydro-1,2,4,6-thiatriazine (Py2TTAH). Oxidation of Py2TTAH with iodine yields the corresponding 1,2,4,6-thiatriazinyl radical, identified by EPR spectroscopy.