3- Nitro-2-methyl-47/-pyrido

Nitro-6-methyl-4//-pyrido[l,2-a]pyrimidin-4-one was prepared from 6-methyl-4//-pyrido[l,2-a]pyrimidin-4-one by nitration with a mixture of concentrated nitric and sulfuric acids at ambient temperature for 2 hours (85JHC481). 

Heating 9-hydroxy-2-methyl-8-nitro-4//-pyrido[ 1,2-a]pyrimidin-4-one 326 in dimethylformamide in the presence of hydrazine hydrate and Raney nickel at 50°C afforded 8-amino derivative 327 (92KGS1660). 8-Amino derivative 327 was also prepared from 8-phenylazo derivative 328. 

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). 

Difluoro-3-methyl-8-nitro-7-oxo-2,3-dihydro-7//-pyrido[l,2,3- /e]-l, 4-benzoxazine-6-carboxylic acid was obtained from 8-unsubstituted derivative by treatment with KNO3 (99MI56). 

Carboxyl group of (-)-9-fluoro-3-methyl-7-oxo-10-[(3S)-3-(tert-butoxy-carbonylamino)pyrrolidino]-2,3-dihydro-7//-pyrido[l,2,3- 7e]-l,4-benzoxa-zine-6-carboxylic acid was converted into l-nitro-2-oxoethyl group in 45% yield by treatment with l,l -carbonyldiimidazole in boiling CFICI3 for 18h, then with MeN02 in the presence of KOr-Bu for another 18 h (96MI12). 6-(2,2-Diethoxycarbonyl)acetyl derivative formed from the aforementioned 6-carboxylic acid, when it was treated with l,l -carbonyldiimidazole in... 

Ethyl (3S)-8-amino-3-methyl-10-(2,6-dimethyl-4-pyridyl)-7-oxo-2,3-dihy-dro-7//-pyrido[l,2,3- f< ]-l,4-benzothiazine-6-carboxylate was obtained by the reduction of the respective 8-nitro derivative (OOMIPIO). 

On the other hand, reaction of 5-acetyl-2-methyl-4-nitro-6-phenyl-3(2//)-pyridazinone 287 with A -methyl-/3-alaninenitrile afforded the 4-(2-cyanoethyl) derivative 288, which was cyclized by heating with sodium ethoxide in ethanol to the pyrido[2,3-rflpyridazine 289 (Equation 22) <1994S669>. 

Amino-l-methyl-527-pyrido[4,3-6]indole (see Trp-P-2) 2-Amino-5-(5-nitro-2-furyl)-l,3,4-thiadiazole 2-Amino-4-nitrophenol 2-Amino-5-nitrophenol... 

H NMR spectra of 117/-pyrido[2,l-b]quinazolin-l 1 -one (27) and its 2-amino, 3-amino, 2-methoxy, 8-nitro, 9-methyl, and 3-chloro derivatives were measured using DMSO-d6 (83MI3). 

Vielsmeier-Haack formylation of 2-nitro-6,7,8,9-tetrahydro-l 1 //-pyrido-[2,l-b]quinazolin-l 1-one (120, R = 2-N02) (84JHC219) and 1,2,3,4,6,7,8,9-octahydro-ll//-pyrido[2,l-6]quinazolin-l 1-one and its 8- and 9-methyl derivatives (87JHC1045) with a mixture of phosphoryl chloride and dimethyl-formamide at 15-20°C gave 6-formyl-2-nitro-5,7,8,9-tetrahydro- (122) and 6-formyl-l,2,3,4,5,7,8,9-octahydro-ll//-pyrido[2,l-b]quinazolin-ll-ones. 

Cyclization of 2-[(3-acetamido-2-pyridyl)amino]benzoic acid (202) in 0.5 N sulfuric acid gave 6-amino-ll//-pyrido[2,l-h]quinazolin-ll-one (203) (84MI3). 2-[(6-Methyl-, 5-nitro-, and 3-nitro-2-pyridyl)amino]benzoic acids were cyclized into 9-methyl, 8-nitro, and 6-nitro-l 1 //-pyrido[2,l -ujquina-zolin-ll-ones, respectively, by the action of 80% sulfuric acid. Ethyl 2-(2-pyridylamino)benzoate, prepared in the reaction of 2-chloropyridine and ethyl anthranilate in boiling toluene for 10 h, afforded ll//-pyrido[2,l-b]-quinazolin-ll-one (27) on heating at 200-210°C for 0.5 h (92MI2). 

Nevertheless, the 9-methyl derivative of 71 failed to produce a quaternary salt because of the steric hindrance effect of the methyl group,137 as did 2-rnethyl-3-nitro-4-oxo-4//-pyrido[l,2- ]pyrimidine37 because of the electron deficiency of the ring. When the pyridopyrimidine bore a substituent containing a nitrogen atom more basic than N-l, the quaternization occurred in that side chain.42... 

The reaction of 3-benzyloxy-, 5-methoxy-, and 5-nitro-2-aminopyridines and 3-acetyl-4,5-dihydro-2(3//)-furanone in warm toluene in the presence of phosphoryl chloride afforded 3-(2-chloroethyl)-2-methyl-4//-pyrido[l, 2-a]pyrimidin-4-ones 102 (84EUP110435 90EUP368388 92USP5158952). 

Ethyl 7-methyl-9-nitro-4-oxo-4//-pyrido[ 1,2-a]pyrimidine-3-carboxyl-ate 142 was obtained when diethyl 2-(pyridyl)aminomethyIenemalonate 141 was cyclized in polyphosphoric acid at 115°C (91H1455). 

The amino moiety of the 3-carbohydrazide group of unsaturated and 6,7,8,9-tetrahydro-4-oxo-47/-pyrido[l,2-n]pyrimidine-3-carbohydrazides was condensed with acetone and 5-nitro-2-furoaldehyde (830MR687 88EUP252809). The reaction of 6-methyl-6,7,8,9-tetrahydro-4-oxo-4//-pyrido[l,2-a]pyrimidine-3-carbohydrazide with diethyl 2-[2-dimethyl-amino)vinyl]-6-methylpyridine-3,5-dicarboxylate in boiling ethanol for 4 hours afforded N-( 1,6-naphthyridin-6-yl)-4-oxo-4//-pyrido[ 1,2-a]pyrimi-dine-3-carboxamide 426 (85MIP1). 

Hydroxy-2-methyl-4//-pyrido[ 1,2-a]pyrimidin-4-one 365 gave 8-sub-stituted derivatives in a reaction with different electrophilic reagents (Scheme 28) (92KGS1660). Nitration gave 8-nitro-9-hydroxy-2-methyl-pyridopyrimidin-4-one 326. Reaction with iodine afforded 8-iodo-... 

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