2-methyl-4-nitro pyrimidines

Extension of this work by studying the reaction of 3-methyl-5-nitro-pyrimidin-4(3//)-one with -X-arylketones in the presence of ammonium acetate surprisingly revealed the formation of a mixture of 4-arylpyrimidines and 6-arylpyridin-2(l//)-ones (00JCS(P1)27). The ratio between pyridine and pyrimidine formation is dependent on the substituent X. With electron-donating substituents the formation of the pyridin-2(l//)-ones is favored, with electron-attracting substituents the formation of the pyrimidine derivatives (Scheme 21) In the formation of the 6-arylpyridin-2(l//)-ones the C-4- C-5-C-6 part of the pyrimidone-4 is the building block in the construction of the pyridine ring. Therefore, the pyrimidone can be considered as an activated o -nitroformylacetic acid (Scheme 21). 

Not until 1967 was covalent hydration found in a single-ring aromatic nucleus, but several examples are now known. The cation of 5-nitro-pyrimidine (also its 2-methyl and 2-benzyl derivatives) adds a molecule... 

R -CH2 X r C=CH-N(CH3)2 X 1,3-Dicarbonyl-Verbindungcn, Nitrile, Ketone, Ester, Alkyl-nitro-bcnzole, Methyl-pyridine, -pyrimidine, Fluoren, Xanthen reagieren in hohen Ausbeuten... 

Pyrimidin-2-amine, 4-ethyI-5-(2 -hydroxy-4 -nitrophenyI)-6-methyl-synthesis, 3, 121 Pyrimidin-2-amine, 4-methyl-basic pXj, 3, 61 Pyrimidin-2-amine, N-methyl-hydrolysis, 3, 84 synthesis, 3, 135 Pyrimidin-2-amine, 5-nitro-basic pXj, 3, 61 hydrolysis, 3, 84 Pyrimidin-2-amine, 4-phenyl-synthesis, 3, 109 Pyrimidin-2-amine, 5-phenyl-nitration, 3, 78... 

Diorganotin(IV) complexes with 4//-pyrido[l,2-n]pyrimidin-4-ones 109 (96MI4), complexes of 2-methyl- and 2-methyl-8-nitro-9-hydroxy-4//-pyrido[l,2-n]pyrimidin-4-ones with Ag(I), Cu(II), Ni(II), Co(II), and Mn(II) ions (00MI23), 2,4-dimethyl-9-hydroxypyrido[l, 2-n]pyrimidinium perchlorate and its complexes with prasedynium, neodymium, samarium and europium (00MI24) were characterized by UV spectroscopy. 

Diorganotin(IV) complexes (109) were prepared from 4/f-pyrido[l,2-a]pyrimidin-4-ones with Me2SnCl2 and Ph2SnCl2 in dry CHCI3 (96MI4). Different complexes of 2-methyl-9-hydroxy-4//-pyrido[l, 2-n]pyrimidin-4-one and its 8-nitro derivative were prepared with Cu(I)Cl, Cu(II)Cl2, Ni(II)Cl2, Co(II)Cl2, Mn(II)Cl2, and Ag(I)N03 m EtOH (00MI23). Complexes of 2,4-dimethyl-9-hydroxypyrido[l,2-n]pyrimidinium salt were obtained with Pr(III), Nd(III), Sm(III), and Eu(III) ions in acetone (00MI24). 

Into a mixture of 1.6 g of 2-amino-4-methylpyrlmidine with 10 ml of glacial acetic acid is slowly added 2.13 g of concentrated sulfuric acid. A mixture of 2.4 g of 2-formyl-1-methyl-5-nitroimidazole in 20 ml of glacial acetic acid is slowly added to the mixture of the pyrimidine under stirring. The reaction mixture is maintained at a temperature of about 55°C for 4 hours. The resultant mixture is then diluted with 200 ml of distilled water and neutralized with a saturated aqueous solution of sodium bicarbonate. A brownish-yellow precipitate (MP 232° to 235°C) is formed and recovered. The product is analyzed by infrared spectroscopy and is found to conform to 2-amino-4-[2-(1-methyl-5-nitro-2-imidazolyI)vinyl] pyrimidine. 

Methyl-5-nitropyrimidin-4(3f/)-one reacts with ketones in the presence of ammonium salts to give 4,5-disubstituted pyrimidines or 5,6-disubstituted 3-nitro-2-pyridones depending on reaction conditions (Eq. 10.83).142... 

Another ring transformation was encountered in the reactions of 5-methoxyfuroxano[3,4- /]pyrimidine 67 with methyl or ethyl acetoacetate in methylene chloride in the presence of triethylamine. This process results in the formation of 2-methyl-5-nitro-3-furancarboxylic esters 68 (Equation 18) <1997CHE879>. 

Ring opening of also a fused [l,2,4]triazole system by secondary amines has been reported. Chupakhin et al. described that 5-methyl-6-nitro[l,2,4]triazolo[l,5-r ]pyrimidin-7(8/f)one 122 underwent ring opening when treated with various secondary amines to yield pyrimidyl ureas 123 in medium to good yield <2001IZV655>, as shown in Scheme 14. 

The reaction of 2-amino-l-methylimidazole hydrochloride and EMME by heating in boiling ethanol in the presence of excess triethylamine overnight gave imidazo[l,2-tf]pyrimidine-6-carboxylate (1115, R = H) in 47% yield [82IJC(B)1030]. The similar reaction with 5-nitro-2-amino-1-methyl-imidazole yielded only a condensation product (1114, R = N02), which... 

The acidic properties of l-methyl-4-dimethylamino-5-nitro-2-oxo-pyrimidine (p/fa 9.04), a molecule with no ionizable proton, have been traced to the structure 30, which is the anion of a hydrate,50 The acidic properties (pKa 10.57) of the corresponding primary amine, 5-nitro-cytosine,51 probably depend on a similar hydration. In solution, 1,3-dimethyl-5-nitrouracil adds water across the 5,6 (C=C) double bond at pH 9.5, but not at neutrality.52... 

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