The cyclocondensation of 6‐acetyl‐4,7‐dihydro‐5‐methyl‐7‐phenyl[1,2,4]triazolo[1,5‐a]pyrimidine (3) with hydroxylamine or hydrazine leads to 3a,4,9,9a‐tetrahydro‐3,9a‐dimethyl‐4‐phenylisoxazolo‐[5,4‐d][1,2,4]triazolo[1,5‐a]pyrimidine (4a) and 3a,4,9,9a‐tetrahydro‐3,9a‐dimethyl‐4‐phenyl‐1H‐pyrazolo[3,4‐d][1,2,4]triazolo[1,5‐a]pyrimidine (4b), respectively. In the presence of methanolic hydrogen chloride, 4b undergoes a cleavage of the pyrimidine ring to yield (5‐amino‐1,2,4‐triazol‐1‐yl)(3,5‐dimethylpyrazol‐4‐yl)phenylmethane (5). The structure determination of the compounds obtained is based on 1H and 13C nmr spectra including NOE measurements.

No abstract

The reaction of 3‐amino‐1,2,4‐triazole (1) with N‐arylmaleimides leads to azolopyrimidines 4 and 5. The 2‐aminobenzimidazole (2) in the reaction with 3 gives the pyrimidobenzimidazoles 6. In similar conditions, the reaction of amine 2 with maleic anhydride (7) leads to formation of 2‐oxo‐1,2,3,4‐tetrahydropyrimido[1,2‐a]benzimidazole‐4‐carboxylic acid (8). The structures of 4, 5, 6, and 8 were proved by X‐Ray and NOE NMR measurements. J. Heterocyclic Chem., (2011)

No abstract

Reactions of 4,7-Dihydro-1,2,4-triazolo [1,5-a]pyrimidines with α,β-Unsaturated Carbonyl Compounds Victoria V. Lipson[a], Irina V. Ignatenko[a], Sergey M. Desenko[b], Svetlana V. Shishkina[b], OlegThe reaction of 5,7-diphenyl-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidine (1) with α,β-unsaturated carbonyl compounds 2a-f led to the formation of the alkylated heterocycles 3a-f (Figure 1). However, the reaction of 5-methyl-7-phenyl-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidine (5) with 2a-c yielded under the same conditions the triazolo[5,1-b]quinazolines 6a-c (Figure 3). In this case, the alkylation is followed by a cyclocondensation. The structure elucidation of the products is based on ir, ms, 1 H and 13 C nmr measurements and on an X-ray diffraction study.

No abstract

in Wiley InterScience (www.interscience.wiley.com).The reaction of 3-amino-1,2,4-triazole (1) with arylidene-5-acetyl barbituric acid (2b,c) or dehydroacetic acid (2a) by refluxing in butanol leads to the formation of dihydro-1,2,4-triazolo[1,5-a]pyrimidines 3a-c.

The reaction of both aliphatic and aromatic thioamide derivatives with N-substituted maleimides under various conditions leads to the formation of complex polycyclic systems [1,2]. No information is available on the reaction of N-arylmaleimides with heterocyclic thiocarboxamide derivatives.We have found that the reaction of 1-aminothiocarbonyl-3,5-diarylpyrazolines 1a-1d [2] with N-substituted maleimides upon heating for 10 min in acetic acid at reflux leads to N-aryl-2-[2-(3,5-diaryl-4,5-dihydro-1H-pyrazol-1-yl)-4-oxo-4,5-dihydro-1,3-thiazol-5-yl]acetamides 2a-d in high yield. This reaction permits broad variation of the substituents R, R 1 , and R 2 in the pyrazolinothiazolone molecules 2, which allows us to synthesize large combinatorial libraries of such compounds. N N N H 2 S R R 1 N O O R 2 N N N S O NH O R 2 R R 1 AcOH 1a-d 2a-d He Hd Hf Ha Hb Hc 1 a R = R 1 = Ph, b R = 4-MeOC 6 H 4 , R 1 = 4-MeC 6 H 4 , c R = 4-FC 6 H 4 , R 1 = 3-ClC 6 H 4 , d R = 2-C 4 H 3 S, R 1 = Ph; 2 a R = R 1 = R 2 = Ph, b R = 4-MeOC 6 H 4 , R 1 = 4-MeC 6 H 4 , R 2 = 4-F, 3-ClC 6 H 3 , c R = R 2 = 4-FC 6 H 4 , R 1 = 3-ClC 6 H 4 , d R = 2-C 4 H 3 S, R 1 = Ph, R 2 = 3-MeOC 6 H 4The structure of products 2a-d was indicated by 1 H and 13 C NMR spectroscopy and mass spectrometry. The 1 H and 13 C NMR spectra were taken on a Varian Mercury VX-200 spectrometer at 200 and 50 MHz, respectively, in CDCl 3 with TMS as the internal standard. The IR spectra were taken on a Perkin Elmer One FTIR spectrometer for KBr pellets. The electron impact mass spectra were taken on a Varian 1200L mass spectrometer at 70 eV.