1.3.4.6- Tetrahydro-1,2,4-triazine 4-oxides formation

Aromatic aldazines when treated in boiling toluene with potassium r-butoxide, furnished 3,5,6-triaryl-l,2,4-triazines (632) and their 2,5-dihydro (633) and 1,2,5,6-tetrahydro derivatives (634), besides triazoles, which were the major products (76JCS(Pl)207). The formation of the triazines is best explained by a [4+2] cycloaddition or a two-step process via the carbanion (631) and elimination of benzalimine to give (633), which can be oxidized to (632 Scheme 21). TTie formation of (634) is still in doubt. 

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