The reaction of 4-amino-substituted 6-hydrazinyl-1,3,5-triazin-2(1H)-ones with triethyl orthoacetate proceeded as a cascade reaction. The initially formed 7-amino-substituted 3-methyl[1,2,4]triazolo[4,3-a][1,3,5]triazin-5(1H)-ones underwent a Dimroth-type rearrangement with the formation of 5-amino-substituted 2-methyl[1,2,4]triazolo[1,5-a][1,3,5]triazin-7(3H)-ones. The latter underwent alkylation at three positions: at the exocyclic oxygen atom with the formation of 7-ethoxy-2-methyl[1,2,4]triazolo[1,5-a][1,3,5]triazines, at the N-3 nitrogen atom with the formation of 3-ethyl-2-methyl[1,2,4]triazolo[1,5-a][1,3,5]triazin-7(3H)-ones, and at the N-1 nitrogen atom to form 1-ethyl-2-methyl[1,2,4]triazolo[1,5-a][1,3,5]triazin-7(3H)-ones. For the latter compound, a retro-Dimroth-type rearrangement occurred with the formation of betaine-type 7-amino-substituted 2-ethyl-3-methyl[1,2,4]triazolo[4,3-a][1,3,5]triazin- 2-ium-5-olates. A possible mechanism for the alkylation of 5-amino-substituted 2-methyl[1,2,4]triazolo[1,5-a][1,3,5]triazin-7(3H)-ones with ortho esters was proposed.

4-氨基取代的6-肼基-1,3,5-三嗪-2(1H)-酮与原乙酸三乙酯的反应以级联反应进行。最初形成的7-氨基取代的3-甲基[1,2,4]三唑并[4,3- a ][1,3,5]三嗪-5(1 H )-酮经历了Dimroth型重排， 5-氨基取代的2-甲基[1,2,4]三唑并[1,5- a ][1,3,5]三嗪-7(3 H )-酮的形成。后者在三个位置进行烷基化：在环外氧原子处形成7-乙氧基-2-甲基[1,2,4]三唑并[1,5- a ][1,3,5]三嗪，在N-3氮原子与形成3-乙基-2-甲基[1,2,4]三唑并[1,5- a ][1,3,5]三嗪-7(3 H )-酮，并在N-1氮原子形成1-乙基-2-甲基[1,2,4]三唑并[1,5- a ][1,3,5]三嗪-7(3 H )-酮。对于后一种化合物，发生逆 Dimroth 型重排，形成甜菜碱型 7-氨基取代的 2-乙基-3-甲基[1,2,4]三唑并[4,3- a ][1， 3,5]三嗪-2-鎓-5-油酸盐。 5-氨基取代的 2-甲基[1,2,4]三唑并[1,5- a ][1,3,5]三嗪-7(3 H )-酮与原酸酯的烷基化的可能机制是建议的。