diethyl 2-(2-methylbut-3-yn-2-yl)propanedioate

diethyl 2-(3-oxocyclohexyl)propanedioate

diethyl 2,2-di(1,2,3,4-tetrahydro-2,4,6-triphenyl-1,2,4,5-tetrazin-1-yl)malonate

2,4,6-triphenyl-1,3-dihydro-1,2,4,5-tetrazine

ethyl 4-chloro-2-oxochromene-3-carboxylate