2-Amino-4-phenyl-l,3,5-triazine

Fluoro-5-phenyl-l,2,4-triazine (109, X = F) reacts much faster than the 3-chloro-, 3-bromo-, or 3-iodo-compound. Moreover, the reaction mixture obtained is cleaner than that from the corresponding 3-chloro- or 3-bromo compounds 3-amino-5-phenyl-l,2,4-triazine (110) is formed in good yield. This conversion takes place to only a small extent (18%) via the ANRORC process the main part of the aminodefluorination seems to involve the Sn(AE) mechanism. This result is consistent with the observation that the aminodefluorination of 4,6-diphenyl-2-fluoropyrimidine follows the Sn(AE) process, whereas 2-fluoro-4-phenylpyrimidine (position 6 is vacant for addition of the nucleophile) reacts for the most part according to the Sn(ANRORC) mechanism (see Section II,C,l,c). 

The methoxy group is replaced in the reaction of 3-methoxy-5-phenyl-1,2,4-triazine 1-oxide 46 with ammonia, resulting in 3-amino-5-phenyl-l,2,4-triazine 1-oxide 47. The treatment of 3-methoxy-l,2,4-triazine 1-oxide 20 with hydrazine leads to 3-hydrazino-l,2,4-triazine 1-oxide 48 (71JOC787). 

Phenylmagnesium bromide converts 3-amino-6-phenyl-l,2,4-triazin-5-ones (164) into 3-amino-5,6-diphenyl-l,2,4-triazines (165) (73JPR221). 

A number of 1,2,4-triazines are of interest owing to their biological activity. 1,2,4-Triazine-3,5-diones (6) represent aza analogues of pyrimidine nucleic acid bases, a number of natural antibiotics are derivatives of pyrimido[5,4-e][l,2,4]triazine (7), and 4-amino-6-r-butyl-3-methylthio-l,2,4-triazin-5-one (8) and 4-amino-3-methyl-6-phenyl-l,2,4-triazin-5-one (9) are used as herbicides. 

Rosen, J.D. and M. Siewierski (1971). Photolysis of 4-amino-3-methylthio-6-phenyl-l,2,4-triazin-5-one (Aglypt). Bull. Environ. Contam. Toxicol., 6 406 108. 

IUPAC 4-amino-4,5-dihydro-3-methyl-6-phenyl-l, 2,4-triazin-5-one 4-amino-6-lert-butyl-4,5-dihydro-3-methylthio-1,2,4-triazine-5-one N,N -diisopropyl-6-methoxy-1,3,5-triazine-2,4-diamine... 

Amino-l,2,4-triazin-5(4//)-ones can be used as agrochemicals, in particular 4-amino-6-te/7-butyl-3-(methylsulfanyl)-l,2,4-triazin-5(4//)-one (11a, Sencor, Metribuzin), 4-amino-6-tert-butyl-3-(cthylsulfanyl)-1,2,4-triazin-5(4//)-one (lib, Ethyl Metribuzin, SMY1500) and 4-amino-3-methyl-6-phenyl-l,2,4-triazin-5(4//)-onc (12, Goltix, Metamitron).23... 

Treatment of methyl 4-nitroso-3-phenylpyrazole-5-carboxylate with phosphorus pen-tachloride and then with ammonia affords methyl 5-amino-6-phenyl-l,2,4-triazine-3-carboxy-late (4).1312 The reaction proceeds via 1-cyanoalkanone 1-chloroalkylidene hydrazones (cf. Section 2.2.1.1.1.5.). 

Electrochemical reduction of 4-amino-3-methyl-6-phenyl-l,2,4-triazin-5(4//)-one, known as the herbicide metami-tron, in acidic media has been studied <1998JEC177>. The first step has been shown to be reduction of the 1,6-azomethine bond by means of transfer of two electrons to the protonated form of 1,2,4-triazinone, while the second step is reduction of the 2,3-azomethine bond. The 1,6-double bond is reduced at potentials approximately 0.5 V more positive than that of the 2,3-azomethine bond <1998JEC177>. It is interesting to note that in the chemical reaction of the same triazin-5(4//)-one with sodium borohydride the 2,3-G=N bond is reduced first <1996JHC2063>. 

Figure 3 Metamitron 5 [Goltix ", 4-amino-3-methyl-6-phenyl-l,2,4-triazin-5(4H)-one].

The semicarbazone of phenacylhydrazine (699) yielded 4-amino-6-phenyl-4,5-dihydro-l,2,4-triazin-3-one (700) on treatment with base (36JPR(144)273). 

One route to these compounds is the reaction of 3-amino-1,2,4-triazoles (312) with dicyanodiamide (485) to yield (49USP2473797 53JOC1610) 5,1-diamino-l,2,4-triazolo[4,3-a]l,3,5-triazines (486). The 1,3,5-triazine ring of 7-methoxy-3-phenyl-l,2,4-triazolo[4,3-a] 1,3,5-triazine (489) was formed (70T3357) by the direct cyclocondensation of 0-methyl-N-(5-phenyl-l,2,4-triazol-3-yl)urea (488) with methyl diethoxyacetate (487) or triethyl orthoformate. 3,5,7-Triamino-1,2,4-triazolo[4,3-a] 1,3,5-triazine (490) was prepared (53JOC1610 63ZOB1355) in one step by the reaction of two equivalents of dicyanodiamide (485) with one equivalent of hydrazine dihydrochloride. 

The diazotization of 5-amino-4-carbamoyl-l-(a-styryl)-l,2,3-triazole (30) gave 5-phenyl-1.2,3-triazolo[l,5-h][l,2,4]triazine-3-carboxamide (32) as a result of rearrangement of the initially formed 7-phenyl-l,2,3-triazolo[5,J-c][l,2,4]triazine-3-carboxamide (31). Compound 32 is favored thermodynamically and its structure was confirmed by an X-ray crystallographic study (88BSB179) (Scheme 10). 

Reaction of dimethyl l,2,4,5-tetrazine-3,6-dicarboxylate with the oxime ether of 4-(dimethyl-amino)benzaldehyde affords dimethyl 5-[4-(dimethylamino)phenyl]-l,2,4-triazine-3,6-dicarb-oxylate (10).342... 

Reaction of 6-benzyl-3-methylthio-4-phenyl-l,2,4-triazines (200) with hydrazine gave the 4-amino-3-anilino-l,2,4-triazin-5(4//)-ones (201) (Equation (20)) <88JHC279>. 

Methylthio-l,2,4-triazin-5(2//)-ones (209) have been converted into 3//-[l,2,4]triazino[3,2-i]quinoxaline-3,10(4//)-diones (212) upon cyclocondensation with anthranilic acid (210) (Scheme 40). A-Methylanthranilic acid (211) with (209) afforded the 5-methyl-3/f-[l,2,4]triazino[3,2- )]quin-azoline-3,10(5//)-diones (213) (Scheme 40). Reaction of 2-methyl-3-methylthio-6-phenyl-l,2,4-tri-azin-5(2//)-one (214) with anthranilic acid (210) gave 1-methyl-3-phenyl-47/-[l,2,4]triazino[3,4-i]quinazoline-4,6(l//)-dione (216) via the intermediate (215) (Scheme 41) <84CB1077, 84CB1083). 3-Alkylthio-4-amino-l,2,4-triazin-5(4//)-ones (217) with anthranilic acid formed l-amino-3/f-... 

Dichloromethyl-5-trichloromethyl-3-phenyl-l,2,4-triazine (307) reacts with hydrazine to give 3-phenylpyrazolo[3,4-e]-l,2,4-triazine (308) (Equation (35)) <90H(3l)l933>. 3-Amino-6-aminomethyl-... 

The list of relatively simple 1,2,4-triazines for which the X-ray data have been obtained involves 3-amino-l,2,4-triazin-5(2//)-one <2002MI723> and a great number of phenyl derivatives 3,6-diphenyl-5-cyano-l,2,4-triazine <2002RJOC744>,... 

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