4- Methyl-l,3,5-triazines

Dynamic aspects of structure have been scarcely treated. MP2/6-31G (d,p) calculations for 1 predict a lowest out-of-plane ring vibration at 302 cm and a population of approximately 20% of the molecules in a nonplanar state at room temperature <2002JMT(616)159>. The rotational barrier of the Me group in 4-methyl-l,2,3-triazine in the 3 o and 3 i electronic states has been examined. When the torsional angle 61 = 0 is defined to represent a conformation with one C-H bond in the ring plane, a minimum in 3 o and a maximum in is found for 61 = 60° <2001JCP8357>. 

Methyl-l,2,3-triazine EtOH 313sh 286 (2.70), 288sh 1981CC1174... 

Reaction of 4-methyl-l,2,3-triazine 86c with sodium amide in liquid ammonia followed by acidification gives 2-amino-3-hydroxycrotonamide (Equation 26) <1985LA1732>, and the mesoionic compound 105 is cleaved by acidified ethanol into diethyl phenylmalonate and 1,3-diphenyltriazene (accompanied by a small amount of its follow-up product 4-aminoazobenzene) (Equation 27) <1978CB2173>. 

The addition of 1-diethylaminopropyne and pyrrolidinocyclopentene to 1 and 4-methyl-l,2,3-triazine 86c gives pyridine derivatives <1985LA1732>. 

The addition of various pyrrolidinocycloalkenes to 4-methyl-l,2,3-triazine 86c leads to cycloalkane- -annelated pyridines <1985H(23)2789, 1986H(24)29> and the extension of this work to the parent compound 1, 5-methyl-and higher methylated 1,2,3-triazines <1989H(29)1809>. 

The effects of solvent and temperature on the direction of the [4+2] cycloaddition of pyrrolidinocyclooctene to 4-methyl-l,2,3-triazine 86c have been studied. The ratio of products 138 and 139 changed while the total yields dropped with increasing temperature (Equation 51) <1988H(27)2213>. 

Copper(II) acetate in refluxing methanol has been used to prepare 3-alkyl-5-methyl-6-phenyl-3,4-dihydro-l,2,3-triazin-4-ones 568 from 2-(alkylamino)-4-methyl-5-phenyl-l,2-dihydropyrazol-3-ones 567 (Scheme 256). Alternatively, this conversion may be achieved, albeit in a slow reaction, using airoxygen in the presence of sodium hydro-gencarbonate <2006EJ03021>. 

The only synthesis of 1-dialkylaminoindazoles is based on a recyclization reaction (83CC1344). Under the action of ethylmagnesium iodide on 4-phenylbenzo-l,2,3-triazine followed by treatment with methyl iodide, the formation of 1-aminoindazole 26a in 44% yield was observed. The same compound (23% yield) with a small amount of amine 26b is formed when methylmagnesium iodide and ethyl iodide are taken instead of ethyl-magnesium iodide and methyl iodide. Supposedly, the reaction occurs as shown in Eq. (7). 

X-ray crystallographic analysis of 6-methyl-4-phenyl-l,2,3-triazine 1-oxide (8),22 1-methyl-4,6-diphenyl-l,2,3-triazinium iodide (9),23 4,6-dimethyl-l,2,3-triazine 2-oxide (10a),19 4,6-diphenyl-1,2,3-triazine 2-oxide (10b),19 4,5,6-triphenyl-l,2,3-triazine 2-oxide (10c),36 4,5,6-tris(4-tolyl)-... 

Reaction of 1,2,3-triazines 1 with A iV-diethylprop-l-ynamine afforded mainly the N,N-di-ethylpyridin-2-amincs 7.17 284 285 When 4-phenyl-l,2,3-triazine (1, R = Ph R2 = R3 = H) was treated with /V,./V-diethylprop-l-ynamine the main product was MiV-diethyl-4-methyl-6-phenylpyridazin-3-amine (6). Its formation can be explained by an attack of A -.A -diethylprop-1-ynamine at N2 and C5 of l.284... 

For calculated values and orientation of the dipole moment /i of 1 and 4- and 5-methyl-l,2,3-triazines, see Section 9.01.2. An experimental value for 1 is not known, but values (determined in dioxane solution) for 3-methyl-3,4-dihydro-l,2,3-benzotriazin-4-one (19f /i=1.69D) and 2-methyl-l,2,3-benzotriazin-2-ium-4-olate (/t = 4.9 D) have been determined earlier <1968PHA629>. 

Diphenyl-5-(4-methoxyphenyl)-l,2,3-triazine has been converted to (4-methoxyphenyl)phenylethyne at 625°C/10 Torr <1981JCM162>. Beyond the preparation of two perfluoroalkynes, namely perfluoro-3-methyl-l-butyne from perfluoro-4,6-diisopropyl-l,2,3-triazine (600 °C, 10 Torr) <1989CC1657> and difluoroethyne from... 

While the parent 1,2,3-triazine 1 is reported not to react with OT-chloroperbenzoic acid (MCPBA) even after 3 days <1992H(33)631>, 4-methyl-1,2,3-triazine 86c, 4,6-dimethyl-l,2,3-triazine 17m, and 4-methyl-6-phenyl-l,2,3-tri-azine 17s gave mixtures of 1-oxides (minor) and 2-oxides (major) when treated with MCPBA or ACOH/H2O2. In contrast, 4,5,6-triphenyl- and 4,6-diphenyl-l,2,3-triazine gave solely the 2-oxides <1996CHEC-II(6)483>. 

Attack of the 1,2,3-triazine system by an organic radical is used in the introduction of a carboxamide function at C-5 by the treatment of 4,6-disubstituted l,2,3-triazin-2-ium 2-dicyanomethylides 34 (R = H R, R = Me, Ph, Et) with formamide in the presence of ammonium persulfate at 80 °C. Under these conditions, the 1,2,3-triazine is restored by loss of dicyanomethyl radical. The corresponding 2-methyl-l,2,3-triazin-2-ium iodides gave the demethylated... 

Naphtho[ 1,2-h]thiophene-2-carboxylic acid synthesis, 4, 893 Naphthothiophenes synthesis, 4, 881, 907, 914 Naphthothiophenes, dihydrosynthesis, 4, 113 Naphtho[ 1,2-c]thiophenes synthesis, 4, 891 Naphtho[2, l-h]thiophenes synthesis, 4, 907 Naphtho[2,3-h]thiophenes synthesis, 4, 905, 908-909 Naphtho[ 1,8-de][l,2,3]triazine, 2-methyl-reactions... 

The intervention of an intermediate with the symmetry of a benzocyclopropenone (166, R = Cl) is also demanded by the formation of methyl p-chlorobenzoate in the photolysis of the lithio derivative 173 of the chlorosubstituted 3-p-tolylsulpho-nylamino-benzo-l,2,3-triazin-4-one128) ... 

Amino-4-cyano-4-methyl-4/f-l,2,3-triazole (291) reacts with formamidine at room temperature to give the substituted l,2,3-triazolo[l,5-a]-l,3,5-triazine (293) via a translocative rearrangement of the presumed intermediate (292) (Scheme 56) <85JOC4986>. 

Betaines 261 are stable crystalline compounds. Knowledge of their chemical reactions is still limited. Alkaline hydrolysis of aryl derivatives (261 R = Ar) gives the 2-azobenzoic acids 266 but the mechanism of this rearrangement is unknown. Reduction by tin and hydrochloric acid gives the hydrazides 267. Thermolysis of the p-tolyl compound (261 R = p-MeC6H4) (120 C at 0.1 mm Hg) gives the isomeric triazine (268 R = >-MeC6H4). Phosphorus pentasulfide converts the 2-methyl derivative (261 R = Me) into 2-methyl l,2,3-benzotriazinium-4-thiolate (272 R = Me) (Section in,B,15). 

---