Reactions of the derivatives of 5,6-diaryl-2,5-dihydro-1,2,4-triazines with dimethyl acetylenedicarboxylate—structural reassignments of the products and further observations

The structures of the dihydro derivatives of 5,6-diaryl-1,2,4-triazines and of the products from the title reactions have been reassigned as 5,6-diaryl-2,5-dihydro-1,2,4-triazines ($\text{5}$a-g) and 2,6-diaryl-4-methyl-5-substituted-1,8-bis-methoxycarbonyl-3,4,7-triaza-bicyclo[3.3.0]octa-2,7-dienes ($\text{7}$a-g), respectively.