Pyrimidin-4-ones nitration

Ac = Acetyl acac = Acetylacetonate bda = Benzylidene-acetone BINOL = l,l -bi-2-naphthol Bn = Benzyl brsm = Yield based on recovered starting material Bu = Bntyl CAN = Ceric anunonium nitrate CBS = Corey/Bakshi/Shibata catalyst [(+) or (—)-(S)-2-methyl-oxazaborolidine] COD = Cyclo-l,5-octadiene COT = Cyclooctatetraene Cp = Cyclopentadienyl Cp = Penta-methylcyclopentadienyl Cy = Cyclohexyl DCC = Dicy-clohexylcarbodiimde DMF = Ai,A-dimethylformainide DMPU = l,3-dunethyl-3,4,5,6-tetrahydro-2(lH)-pyrimidin-one DMSO = Dimethylsnlfoxide dppe = Diphenylphosp-hinoethane dr = Diastereomer ratio dppm = Diphenylphos-phinomethane E = Electrophile ee = Enantiomeric excess EHMO = Extended htickel molecular orbital Et =... 

Nitration of 2-substituted 4/7-pyrido[l,2- ]pyrimidin-4-ones with 99% HN03 in cone. H2S04 gave 3-nitro derivatives <2000BMC751, 2001H(55)535>. Mannich reaction of 2-hydroxy-4//-pyrido[l,2-tf]pyrimidin-4-one afforded... 

Pyrazine and pyrimidine heterocycles, like pyridine, are electron deficient and need the presence of an activating/electron-releasing group to allow efficient electrophilic nitration to occur. An example of this strategy is seen during the synthesis of 2,6-diamino-3,5-dinitropyrazine (ANPz) (183) where one of the chloro groups of 2,6-dichloropyrazine (180) is substituted for a... 

Nitration of 4,5-dichloro-2-methylpyridazin-3-one occurs at position 6. Pyrimidin-2-one is nitrated under vigorous conditions to give the 5-nitro derivative, whereas l-methylpyrimidine-2,4-dione yields the 5-nitro derivative at 25°C. 

Imidazo[4,5-c]pyridin-4(5H)-ones chlorination, 5, 621 Imidazo[ 1,2-a]pyrimidine, 2-phenyl-nitration, 5, 627... 

Pyrimidinones, 5-methylsulfonyl-synthesis, 3, 138 Pyrimidin-2-ones IR spectra, 3, 64 Pyrimidin-2( 1H)-ones acidic pKa, 3, 60 alkylation, 3, 90 nitration, 3, 69 pKa> 3, 60 reduction, 3, 75 synthesis, 3, 132 Pyrimidin-4(3/7)-ones alkylation, 3, 90 synthesis, 3, 132 thiation, 3, 89 Pyrimidinophanes synthesis, 7, 768, 774 Pyrimidinopurinophanes synthesis, 7, 766 Pyrimidin-2-yl thiocyanate synthesis, 3, 95... 

Formyl derivative 362 was prepared when 9-hydroxymethylpyrido-pyrimidin-4-one 361 in dichloromethane was added to a cooled mixture of oxalyl chloride and dimethyl sulfoxide at - 50°C/ - 60°C in the presence of triethylamine. 9-Formyl derivative 362 was oxidized with silver nitrate in aqueous ethanol, and after 15 minutes of stirring the reaction mixture was treated with aqueous potassium nitrate for 2 hours at ambient temperature to give pyrido[ 1,2-a]pyrimidine-9-carboxylic acid 363 (91EUP453042). 

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). 

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-... 

Oxidation of 3,4-dihydropyrimidin-2(l //)-oncs (DHPMs) with ceric ammonium nitrate (CAN) in acetic acid resulted in ethyl 2,4-dioxo-6-phenyltetrahydropyrimidin-5-carboxylates as the major product. However, DHPMs undergo a regioselective oxidation with CAN in the presence of sodium hydrogencarbonate in neutral aqueous acetone solution to yield ethyl 6-meihyl-4-aryl(alkyl)pyrimidin-2(l //)-one-5-carboxylates. A mechanism involving a nitrolic acid intermediate has been suggested.72... 

The similarities in rate of nitration for the uracils suggest that they are all nitrated in the dioxo forms [log /r2(fb) at 40-50°C at H0 - 10.26 uracil, 1,3 1,3-dimethyluracil, 1.7 6-methyluracil, 1.9]. 2,4-Dimethoxypyrimid-ine is slower by a factor of 104. Whereas pyrimidin-2(l//)-one and its 1-methyl derivative also react as the free bases, the rates are much lower than those of the corresponding uracils [log /c2(fb) at 115°C at H0 -9.27 for pyrimidin-2(l//)-one is 8.1 for the 1-methyl derivative the value is 8.8], and 100 times slower than 3-methyl-2-pyridone. These results reflect the deactivating effect of a second annular nitrogen and the presence of only one oxo function [71JCS(B)1]. 

Chloroperoxidase catalysis by, 58, 302 in chlorination of pyrazoles, 57, 337 Chlorophyll, thioaldehyde synthetic intermediate to, 55, 3 Chlorosulfonyl isocyanate, reaction with 2-arylhydrazono-3-oxobutanoate, 59, 148 Chromatography, of [l,2,4]triazolo[l,5-a]-pyrimidines, 57, 106 Chrom-3-enes, see 2//-l-Benzopyrans Chromium tricarbonyl complexes of 3,5-diphenyl-l-(alkyl- or oxido-)-thiabenzenes, 59, 206, 227 indoles, lithiation of, 56, 181, 184 of pyridine, 58, 160 pyridines, lithiation of, 56, 230, 239 of 2f/-thiopyrans, 59, 227 Chromones, see l-Benzopyran-4-ones Cinnamonitrile, a-cyano-, condensations with thio-, seleno-amides, 59, 184, 186 Cinnoline, nitration, MO calculation, 59, 302... 

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