4-Pyrimidinone

Hydramethylnon [67485-29-4] is tetrabydro-5,5-dimetbyl-2-(1 H)-pyrimidinone [bis-l,5-(4-trifluoromethylphenyl)-3-penta-l,4-dienylidene] hydrazone (152) (mp 189°C). It is a slow-acting stomach poison used in baits and traps to control ants and cockroaches. Its mode of action is inhibition of mitochondrial electron transport. 

Propylene Urea Resins. In similat fashion to ethyleneurea, dimethyl-olpropyleneurea [3270-74-4] [l,3-bis(hydroxymethyl)tetrahydro-2-(m)-pyrimidinone] is the basis of propyleneurea—formaldehyde resin [65405-39-2], Its preparation is from urea, 1,3-diaminoptopane [109-76-2] and formaldehyde. 

This drug also is reported to activate macrophages, to iaduce polyclonal B-ceU activation as well as enhance specific antibody production m vivo, and to iaduce the synthesis of iaterferon and interleukin 1 (52). The iaduction of these important cytokiaes (and others) largely accounts for the profile of biological activity displayed by the pyrimidinones. Bropirimine is currentiy ia clinical evaluation for cancer, arthritis, and immunorestoration ia AIDS patients. 

The required triamino-4(3H)-pyrimidinone is prepared in three steps starting from guanidine [50-01-1] (14) (26). Condensation with methylcyanoacetate [105-34-0] (15) under basic conditions, followed by nitrosation of the intermediate [56-06-4] (16), gives... 

Since IR spectra are essentially due to vibrational transitions, many substituents with single bonds or isolated double bonds give rise to characteristic absorption bands within a limited frequency range in contrast, the absorption due to conjugated multiple bonds is usually not characteristic and cannot be ascribed to any particular grouping. Thus IR spectra afford reference data for identification of pyrimidines, for the identification of certain attached groups and as an aid in studying qualitatively the tautomerism (if any) of pyrimidinones, pyrimidinethiones and pyrimidinamines in the solid state or in non-protic solvents (see Section 2.13.1.8). 

Preliminary IR spectral studies were said to suggest that pyrimidinones existed as pyrimidinols <50JCS3062) but this conclusion was promptly reversed <52JCS168) on better experimental evidence subsequent comparison with their N- and O-methyl derivatives showed that the pyrimidinones (39a R = H) and (40a R = H) along with their A-methyl derivatives (39a R = Me), (40a R = Me) and (40b R = Me) all exhibited vqo in the range 1600-1700 cm, whereas the methoxypyrimidines (39b R = Me) and (40c R = Me) showed no such absorptions <53JCS33l, 55JCS211). Closer analysis of the spectra for pyrimidin-4-one (40a R= H) showed that the ort/jo-quinonoid form (40a R = H) is the predominant tautomer (see Section 2.13.1.4). 

Quinazolin-2(and 4)-one were first shown to exist as 0x0 tautomers by IR and UV spectroscopic comparisons akin to those above (52JA4834, 51JCS3318) like its pyrimidinone analogue, the quinazolinone (41) prefers that configuration to the pczra-quinonoid tautomer (57JCS4874), a conclusion upheld by the NMR study of simple analogues (69T783). 

The preparation of hydroxypyrimidines must be divided into two categories, pyrimidinones (2- or 4/6-hydroxypyrimidines) and pyrimidinols (5- or extranuclear hydroxypyrimidines) simply because the approaches are different. 

Pyrimidine-4/6-thiones (and occasionally 2-thiones) can be made by thiation of the corresponding pyrimidinones providing that there are no sensitive groups present. The method is summarized and exemplified in Section 2.13.2.2.7/). 

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