Pyrimidine 4-hydroxy- from

Cyclopent-2-en-l-one, 2-hydroxy-3-methyl-synthesis, 3, 693 Cyclopentenone, 4-methoxy-formation, 1, 423 Cyclopenthiazide as diuretic, 1, 174 Cyclopent[2,3-d]isoxazol-4-one structure, 6, 975 Cyclophane conformation, 2, 115 photoelectron spectroscopy, 2, 140 [2,2]Cyclophane conformation, 2, 115 Cyclophanes nomenclature, 1, 27 Cyclophosphamide as pharmaceutical, 1, 157 reviews, 1, 496 Cyclopiloselloidin synthesis, 3, 743 Cyclopolymerization heterocycle-forming, 1, 292-293 6H-Cyclopropa[5a,6a]pyrazolo[l,5-a]pyrimidine pyrazoles from, 5, 285 Cydopropabenzopyran synthesis, 3, 700 Cyclopropachromenes synthesis, 3, 671 Cyclopropa[c]dnnolines synthesis, 7, 597 Cyclopropanation by carbenes... 

Figure 2. Formation of hydrolysis product, 2-isopropyl-6 methyl-4 hydroxy pyrimidine (H) from C-diazinon (D) incubated with water from a rice field treated previously with diazinon (19)...

Hydroxy- from chloro-pyrimidines s. 12, 433 Carboxylic acids... 

The synthesis of pyrimidine nucleosides from glycosyl bromides having the 2-hydroxy group unsubstituted gave 1,2-trans products stereospecifically the mechanism of the reaction was discussed. 

The reaction of 6-amino-5-(l,2-diethoxycarbonylhydrazino)pyrimidines with enamines represents another convenient method for the preparation of pteridines. Fusion of 5-(l,2-diethoxycarbonylhydrazino)-2,4,6-triaminopyrimidine (281) with an excess of mor-pholinocyclohexene leads to 2,4-diaminotetrahydrobenzo[g]pteridine, and with the morpholinoenamine (282) from 17/3-hydroxy-5a-androstan-3-one regioselective condensation to the fused pteridine (283) takes place in almost quantitative yield (equation 101) (71CC83). 6-Amino-5-nitroso- and 6-amino-5-phenylazo-pyrimidines react similarly, imitating the Timmis-type reaction (72CPB1428). 

According to the systematic nomenclature these substances were first named l-f-triazolo[d] pyrimidines in compliance with the general principles of the Ring Index/ More recent papers and Chemical Abstracts indexes use the term i -triazolo[4,5-d]pyrimidine (147) in accord with the lUPAC nomenclature. The numbering of substituents when using the last-mentioned name is different from that of the 8-aza analogs. For the formulas of oxygen and sulfur derivatives names derived from the lactim or thiolactim form are almost exclusively in use (in common with the purine derivatives). These derivatives are thus described as hydroxy and mercapto derivatives, respectively. The name 1,2,3,4,6-pentaazaindene is used only rarely for this system. 

Vilsmeier-Haack formylation of 2-(4-methyl-l-piperazinyl)-4//-pyrido-[l,2-n]pyrimidin-4-one with a mixture of POCI3 and DMF at 95°C gave a 3-formyl derivative (93FES1225) while ethyl 4-oxo-6,7,8, 9-tetrahydro-4//-pyrido[l,2-n]pyrimidine-2-acetate at 50 °C yielded a 9-dimethylaminomethylene-3-formyl derivative (01MI4). 3-Formyl-2-hydroxy-8-[2-(4-isopropyl-l,3-thiazol-2-yl)-l-ethenyl]-4//-pyrido[l,2-n]pyri-midin-4-one was obtained from the 3-unsubstituted derivative with oxalyl chloride-DMF reagent in CH2CI2 at room temperature for 3h (OlMIPl). 

Methoxy-4//-pyrido[],2-n]pyrimidin-4-one was prepared from 2-chloro-4//-pyrido[],2-n]pyrimidin-4-one with NaOMe in MeOH for 16h, and from n /iyJro-(2-hydroxy-4-oxo-4//-pyrido[l, 2-n]pyridinium)hydroxide with Me2S04 in the presence of NaOMe in MeOH for 3h at room temperature in 93% and 41% yields, respectively (99JCS(P2)1087). 2-(2-Hydroxyethoxy)-4//-pyrido[],2-n]pyrimidin-4-one was prepared from the 2-chloro derivative with HOCH2CH2OH in the presence of K2CO3 at 160 °C for 1 h (00BMC751). 

Reaction of 2-hydroxy-4//-pyrido[l,2-u]pyrimidin-4-ones 168 and 2-chloromethylsaccharins 169 in the presence of a base gave 2-<9-alkylated products 170 (94EUP626378, 95JMC4687, 95USP5378720). From the reaction mixture of 3-chloro derivative 168 (R = H, R = Cl) and... 

Fluorophenyl)-3-fluoro-2-hydroxy-6-oxo-6/7-pyrido[],2-n]pyrimidine-7-carboxylic acid (197, R = 4-FPh, R = H) was obtained from the 2-(4-methyl-]-piperazinyl)-7-ester derivative by the treatment with 1 N NaOH in an 1 1 mixture of H2O and THF at room temperature for 6h (95MIP1, 96JMC3070, 96MIP4, 96USP5580872). 

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). 

The structures of pyrrolo[l,2-c]pyrimidine 139 and its N-protonated form 140 were obtained from MP2/6-31G calculations (Scheme 92) [99JOC7788]. Proton affinities computed at the same level reveal that N-protonation is slightly preferred over protonation at the C7 position. The most stable tautomers of 2-substituted 5-methyl-7-hydroxy-l,2,4-tiiazolo[l,5-a]pyrimidine 141 were... 

Unfortunately, the two fuU papers on the silylation-amination of pyrimidine [49] and purine nucleosides [64] as discussed in Sections 4.2.3 and 4.2.4, were pubhshed in German and are thus not readily accessible, although a few detailed procedures from Sections 4.2.3 and 4.2.4 were subsequently published in English [65]. The third paper on the silylation-amination of aromatic hydroxy-N-hetero-cycles, however, as discussed in Section 4.2.5 was, fortunately, pubhshed in English [27]. 

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