5-Phenyl-7-methyl-1,2,4-triazolo pyrimidine

Crude 5-methyl-3-phenyl-v-triazolo[3,4-a]pyrimidin-7(4H)-one heated 2 hrs. at 140 7-methyl-3-phenyl-v-triazolo[3,4-a]pyrimidin-5(4H)-one. Y ca. 100%. Reverse rearrangement in the presence of piperidine s. D. R. Sutherland, G. Tennant, and R. J. S. Vevers, Soc. Perkin I 1973, 943. 

Reaction of 4-chloro-5-methyl-6-phenyl-2-pyrimidinamine (566) with formylhydrazine yielded a mixture of triazolo[4,3 c]pyrimidine (567) and its [l,5-c]isomer 568 (83USP4405780), and boiling 566 with formylhydrazine in DMF containing a 3-A molecular sieve afforded 567 (81GEP3029871) (Scheme 110). 

The reaction of 2-thiovioluric acid (69) with hydrazine hydrate in boiling ethanol afforded triazolopyrimidine derivative 70, but in boiling acetic acid yielded N-acetyltriazolo[4,5-d]pyrimidine derivative 71. In the same manner, the N-phenyl and A-methyl-l, 2,3-triazolo derivatives 72 and 73 were obtained through the condensation of 69 with phenylhydrazine and with methylhydrazine, respectively (91MI1) (Scheme 13). 

DIETHYL-0-(p-(METHYLSULFINYL)PHENYL) PHOSPHOROTHIOATE see FAQ800 0,0-DIETHYL-0-p-(METHYLSULFINYL)PHENYL THIOPHOSPHATE see FAQ800 N,N-DIETHYL-5-METHYL-(l,2,4)TRIAZOLO(l,5-a)PYRIMIDINE-7-AMINE see DI0200 DIETHYL-NICODYMIDE see DJS200... 

Finally, there are syntheses where the 3 and 4 positions of the triazole become incorporated in a new ring. 4-Amino-5-phenyltriazole, acetylacetone, and sodium hydroxide, when refluxed in ethanol, gave 5,7-dimethyl-3-phenyl-l,2,3-triazolo[3,4-fl]pyrimidine (lOI) (10 min, 91%) (three related examples also cited) [71JCS(C)2156], Similarly, 4-amino-5-phenyltriazole, ethyl acetoacetate, and piperidine, refluxed for 2 hr in ethanol, gave a mixture of 5-methyl-3-phenyl-l,2,3-triazolo[3,4-a]pyrimidin-7(4//)-one (68%) with the 7-methyl isomer (17%) [73JCS(P 1)943], 4-Amino-5-phenyltriazole, condensed with l-methylbut-2-en-l-ol in a mixture of trifluoroacetic and perchloric acids, produced 2,3-diphenyl-l,2,3-triazolo[l,5-a]pyridinium perchlorate (102) (78KGS1422). 

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