5-Chloro-6-phenyl-1,2,4-triazine

The 11 NMR spectrum (500MHz) of 3-(4-chloro-phenyl)-7-ethyl-7,9-dimethyl-2,3,4,9-tetrahydropyrimido[l,2-tf]-[l,3,5]triazine-6,8-dione 49 <2002JHC663> showed the presence of quartets (AB pattern) at 6 4.99 and 6 5.12 corresponding to the methylene protons of the triazine ring. 

Phenyl-Substituted Phenols (V). 2,4-Di-octadecanoxy-6-chloro-s-triazine (16). To a solution of 18.4 g of cyanuric chloride (0.1 mol) and... 

Chloro-5,6-diphenyl-as-triazine readily undergoes methoxy-de-chlorination at 25° (< 12 hr) with methanolic methoxide and at 65° (4.5 hr) in non-basified methanol. The chloro group is also displaced by hydrazine (80°, 1 hr), ammonia (140°, 6 hr), and phenyl-magnesium bromide (70°, 12 hr), the latter forming the triphenyl compound 315.3-Chloro-6-phenyl-as-triazine is unstable to cold water or alkali and to hot alcohol or aqueous potassium carbonate. ... 

At the same time, the reaction of 1,2,4-triazine 4-oxides 55 with the anion of chloromethyl phenyl sulfone affords 5-(l-chloro-l-phenylmethyl)-l,2,4-triazines 66. In this case, autoaromatization of the a -adducts proceeds by the deoxygenative... 

A novel route to functionalised 3-aminq)yridazines 77 is the reaction of 3-chloro-6-phenyl-1,2,4-triazine with C-nucleq)hiles. The mechanism proposed for this reaction is shown in Scheme 13 <96TL5795>. 

The parent heterocycle of pyrido[2,3-e][l,2,4]triazine and its phenyl derivative 39 were prepared (89JHC475) by cyclization with polyphos-phoric acid of 3-acyIhydrazino-2-aminopyridines 36, obtained by reduction of the corresponding 3-acylhydrazino-2-nitropyridines 35. Compounds 35 were obtained from 3-fluoro-2-nitropyridine 34 either by reaction with benzoylhydrazine or by reaction with hydrazine and subsequent for-mylation of the initially formed 3-hydrazino-2-nitropyridine 38. Attempts to prepare 38 from 3-chloro-2-nitropyridine gave 2-hydrazino-3-chloropyridine 37. These results could be explained by semiempirical calculations (CNDO and MNDO calculations). 

The reaction of 5-chloro-6-methyl-3-phenyl-l,2,4-triazine and diethyl malonate in the presence of sodium hydride in THF at ambient temperature for 12-24 hr gave malonate (489) in 65% yield (87H3259). 

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). 

Comparison of this reactivity order with that found in the amination of 2-X-4-phenyl pyrimidines (SCH3 Br = Cl > F > SO2CH3 I > (013)3 > CN see Table 11.5 in Section ll,C,l,d) shows that these reactivity orders differ considerably. The fluoro substituent, especially, which has in the pyrimidine series about the same reactivity order as the chloro or bromo atom, shows in the 1,2,4-triazine series a low ANRORC activity. Comparison of both series of reactivities is, however, a delicate matter, mainly because the yields obtained for the amino compounds in the 1,2,4-triazine series are much lower than those obtained in the pyrimidine series, because of the occurrence of many side reactions, such as ring contraction, dehalogenation, ring transformations, and degenerate ring transformations... 

As mentioned in Section II,D,l,a, the presence of a r-butyl or phenyl group at position 5 of the 1,2,4-triazine ring does not prevent addition of the amide ion to that position. Therefore, it becomes of interest to investigate whether in the amino-dehalogenation of two annelated 3-chloro-l,2,4-triazines, i.e., 3-chloro-l,2,4-benzotriazine (123) and 3-chlorophenanthro[9,10-e]l,2,4-triazine (125), using potassium amide/liquid ammonia, the Sn(ANRORC) process would be involved. Both compounds... 

It was reported that 7-chloro-3-phenyl-4H-pyridazino[6,1 -c ]-1,2,4-triazine underwent reaction with hydrazine to give the unexpected product (146) (69AC(R)552). However, it was later established that the assigned structure for this reaction product was incorrect, and the correct hydrazino structure (147) for this product was confirmed by an independent synthesis (70S180). 

Treatment of 3-chloro-6-phenyl-l,2,4-triazine A with 1.1 equivalents of phenylacetonitrile in dry N.N-dimethylacetamide at 0°C in the presence of an excess of KOlBu for one hour followed by quenching of the reaction mixture with ice-water gave an 86% yield of a dinitrile B, C17H12N4. Treatment of B with 1 1 aqueous ammonia/acetone for one hour resulted in quantitative conversion into 3-amino-4,6-diphenylpyridazine, C. The triazine A was converted directly into the pyridazine C when DMF was used as solvent and the reaction mixture was quenched with aqueous acetic acid. 

The products obtained from the treatment of C-acetyl-N-(3-phenyl-4-R-5-pyrazolyl)methanehydrazonoyl halides 5a,b,d,l with triethylamine in benzene or ethanol are the pyrazolof 1,5-c]-1,2,4-triazoles 169a-d, respectively (77JHC227 80JHC209 92MI1). However, treatment of 5a with sodium acetate in ethanol yielded 6-chloro-7-methyl-2-phenylpyra-zolo[5,1-c]-1,2,4-triazine 170. Solvolysis of 170 in aqueous sodium hydroxide gave 171. Attempted cyclization of 5a with methylamine or hydrazine hydrate in methanol gave 171 directly (77JHC227). 

The reactivity of the s-triazine system is so great that the tri-chloro derivative undergoes nucleophilic substitution by the phenyl TT-electrons of diethylaniline (forming 253), by the ethylenic... 

Formation of 1,3,5-triazine derivatives has also been observed in the reaction of 3-halo-5-phenyl-1,2,4-triazines with potassium amide in liquid ammonia (80JOC881) and on treatment of 3-chloro-5,6-diphenyl-l,2,4-tri-azine with phenylmagnesium bromide (83IJC(B)559). Both transformations were assumed to be initiated by the addition of the nucleophile employed at C-5 of the 1,2,4-triazine ring. 

Chloro-3-(4-nitrophenyI)-6-phenyl-l,2,4-triazine (OH - Cl) Typical Procedure 189... 

Treatment of A-phenylbcnzimidoyl chloride (15) with 2,2,2-trichloro-N-cyarurace timid amide (16) in 1,2-dimethoxyethane at room temperature for 20 hours gives 2-chloro-4-phenyl-6-(trichloromethyl)-l,3,5-triazine (17) in a 28 % yield. The mechanism of this conversion is open however, liberation of aniline during the reaction has been observed.366... 

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