Synthesis of nitrogen‐containing heterocycles 9. Preparation and carbon‐carbon bond cleavage of spiro[cycloalkane[1′,2′,4′]‐triazolo[1′,5′‐a][1′,3′,5′]triazine] derivatives and related compounds

Abstract

Diaminomethylenehydrazones of cyclic ketones 1–5 reacted with ethyl N‐cyanoimidate (I) at room temperature or with bis(methylthio)methylenecyanamide (II) under brief heating to give directly the corresponding spiro[cycloalkane[1′,2′,4′]triazolo[1′,5′,‐a][1′,3′‐5′]triazine] derivatives 7–12 in moderate to high yields. Ring‐opening reaction of the spiro[cycloalkanetriazolotriazine] derivatives occurred at the cycloalkane moiety upon heating in solution to give 2‐alkyl‐5‐amino[1,2,4]triazolotriazines 13–16. Diaminomethylenehydrazones 17–19, of hindered acyclic ketones, gave 2‐methyl‐7‐methylthio[1,2,4]‐triazolo[1,5‐a][1,3,5]triazines 21–23 by the reaction with II as the main products with apparent loss of 2‐methylpropane from the potential precursor, 2‐tert‐butyl‐2‐methyl‐7‐methylthio[1,2,4]triazolo[1,5‐a]‐[1,3,5]triazines 20, in good yields. In general, bis(methylthio)methylenecyanamide II was found to be a favorable reagent to the one‐step synthesis of the spiro[cycloalkanetriazolotriazine] derivatives from the diaminomethylenehydrazones. The spectral data and structural assignments of the fused triazine products are discussed.

Synthesis of nitrogen‐containing heterocycles 10. Reaction of 2‐amino‐1h‐imidazole derivatives with ethoxymethylene compounds

“…This compound was obtained in 98 % yield as yellow needles, mp 186-187º; 1 : C,63.14;H,5.30;N,21.66. Found: C,62.94;H,5.27;N,21.54.…”

“…The organic phase was washed with water, dried over sodium sulfate, and then evaporation under reduced pressure to give pale yellow crystals (0.76 g, 71 %), mp 164-165º. Recrystallization from 2-propanol gave pale yellow prisms (0.66 g, 62 %), mp 167º; 1 …”

“…The separated crystals were collected, washed with methanol, and then dried to give 6a as a crystalline powder (0.035 g, 41 %). Recrystallization from methanol gave the analytically pure sample of as yellow needles (0.031 g, 36 %), mp 238-240º; 1 6-Cyano-5-imino-1-isopropylideneamino-3-phenyl-1H-imidazo [1,2-a]…”

“…The crystals gradually deposited from the solution, and were collected by filtration to give 0.1 g (50 %) of analytically pure 9 as pale yellow needles, mp 148-151º; 1 Anal. Calcd.…”

“…The precipitated crystals were collected, washed with acetonitrile, and then dried to give yellow crystals (0.23 g, 83 %), mp 218-220º. Recrystallization from methanol gave yellow needles (0.21 g, 76 %), mp 218-220º; 1 Anal. Calcd.…”