Pyrimidine compounds, vinyl

In cases where there is a suitable leaving group, such as chloro, alkoxy, or amino, the nucleophilic attack at the activated vinyl system of the C—C —C fragment will be followed by the reestablishment of the C—C double bond, the result being a vinylic substitution. In these cases the final cyclization affords the pyrido[2,3-d]pyrimidine compound, or otherwise its dihydro derivative. 

Pyrido[],2-a]pyrimidine-3,7-dicarboxylate 396 was also obtained in the reaction of diazo compound 395 and methyl vinyl ketone in boiling benzene in the presence of a catalytic amount of ruthenium acetate. 

Relatively few simple pyrimidine monomers have been incorporated into heterocyclic polymers (70MI11100). By far the greatest efforts with this ring system have involved polymerizable derivatives of nucleic acid bases and related compounds (81MH1102). The majority of this work has involved the synthesis and free radical polymerization of suitable vinyl- and acrylic-functional monomers, e.g. (134)-(136), although epoxy and other derivatives have also been studied. A number of the polymers exhibit base-paired complex formation with natural nucleic acid polymers or synthetic analogues, have found use in... 

Oxo-4//-pyrido[l,2-a]pyrimidine-7-carboxylates 500 were obtained when 7-iodo-4T/-pyrido[ 1,2-a]pyrimidines 499 reacted with carbon monoxide in the presence of bis(triphenylphosphine)palladium(II) chloride catalyst and triethylamine (Scheme 29) (94MI2). From 7-iodo derivatives 499, 7-vinyl derivatives 501 and 7-(l-ethoxyvinyl) derivatives 502 were prepared with vinyltributyltin in the presence of Pd(PPh3)4 and with (1-ethoxy-vinyl)tributyltin in the presence of bis(triphenylphosphine)palladium(II) chloride catalyst, respectively, in toluene at 80°C. 7-(l-Ethoxy vinyl)pyr-ido[l, 2-a]pyrimidin-4-ones 502 were hydrolyzed to yield 7-acetyl derivatives 503. The acetyl group of compounds 503 was reduced with sodium borohydride in the presence of cerium(III) chloride in ethanol to give 7-(1 -hydroxyethyl)pyridopyrimidin-4-ones 504. 

The formal addition of perfluorinated pyridine, pyrimidine, pyridazine or of pentafluorobenzo-nitrile to fluorinated acetylenes in the presence of cesium fluoride in sulfolane leads to fluorinated aryl-substituted alkenes. " In the first reaction step fluoride ion adds to the fluorinated acetylene to give a vinyl carbanion, which substitutes, in a second step, a fluoride ion from the perfluorinated aromatic compound. Some examples of this type of reaction are shown by the formation of... 

Other synthons for 1,3-dicarbonyl compounds that have been successfully applied include p-chloro-a,P-unsaturated ketones and aldehydes, P-dimethylamino-a,P-unsaturated ketones (easily obtained from ketones by reaction with DMFDMA), P-alkoxy-enones"" and vinyl-amidinium salts."" Alkynyl-ketones react with 5-alkyl-isothioureas, giving 2-alkylthio-pyrimidines" and propiolic acid reacts with urea to give uracil directly in about 50% yield. "" 1,3-Keto-esters with formamidine produce 4-pyrimidinones"" and C-substituted formamidines with ethyl cyanoacetate give 2-substituted-6-amino -pyrimidinones. In analogy, pyrimidines fused to other rings, for example as in quinazolines, can be made from ortho-aminonitriles " and in general, from P-enamino esters. ... 

An attempt to generate 2-(trichloromethyl)pyrimidine 198, from 196 and phenyl vinyl sulfoxide 197, failed and produced 2-(trichloromethyl)-4-(dimethylamino)-l,3,5-triazine 203 as the only isolable product (20%) (Scheme 30). This compound is suggested to arise as a consequence of a partial fragmentation of 196 to A, A -dimethylformamidine 199 and trichloroacetonitrile 200 <1996JOC2470>. 

For example, 5-acryloyloxyethoxycarbonylmethyl-7-hydroxy-1,2,4-triazolo[1.5-a]pyrimidine, c.f. Figure 9.7, can be obtained from 7-hydroxy-5-carboxymethyl-l,2,4-triazolo[l,5-a]pyrimidine by esterification with 2-hydroxyethyl acrylate. This compound has a vinyl group, thus it can be copolymerized with vinylic monomers. 2-Acrylamido-2-methylprop-... 

Some carbocyclic nucleoside phosphonates have been described. There has been a further report on compounds of type 208 (see Vol. 28, p. 291), with both purine and pyrimidine bases. Although initially made as racemates, a precursor diol could be resolved by enantioselective acetylation using a lipase and vinyl acetate.The triphosphate analogues 209 (B=Gua, Ade) have been made from the previously-described monophosphonates (Vol. 29, p. 285), and the cyclopropyl-fused diphosphate analogues 210 (X=CH2 and O) were also reported, along with their enantiomers. Trani-compounds of type 211 (n=l-3) have been made as racemates,and so have the related cw-isomers (n=l or 2). ... 

PVC (Sect. 11.11) A polymer called poly(vinyl chloride), formed from the polymerization of vinyl chloride (H2C=CHCI). pymnose (Sect. 24.5) A six-membered cyclic hemiacetal form of a carbohydrate, pyrimidine (Sect. 23.11) A compound that is similar in structure to pyridine but contains one extra nitrogen atom at the 3 position. 

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