Purine N-oxides: XXXVII. Derivatives from 6-chloropurine 3-oxide

Interaction of 6-chloropurine 3-oxide with several amines led to 6-substituted purine 3-oxides. 6-Chloropurine 3-oxide and selenourea gave 6-selenopurine 3-oxide. 6-Mereaptopurine 3-oxide, prepared from the 6-chloro derivative and ammonium dithioearbonate, was transformed with chlorine and hydrogen fluoride into 6-purinesulfonyl fluoride 3-oxide which upon ammonolysis afforded purine-6-sulfonamide 3-oxide. Methanelhiol and 6-ehloropurint: 3-oxide yielded the known 6-methylthiopurine 3-oxide, which by treatment with chlorine was oxidized to 6-methyl-sulfonylpurine 3-oxide. Reaction of the latter with hydroxylamine led to an improved synthesis of 6-hydroxylaminopurine 3-oxide, which by interaction with manganese dioxide was transformed into 6-nitrosopurine 3-oxide.     

Alkylation and acylation of 2-aminopyrimidine N-oxides

Products of both O- and N-acylation are formed in the acylation of 2-aminopyrimidine N-oxides, whereas only O-alkylation products are formed by the action of alkylating agents. The reaction of 2-aminopyrimidine N-oxides with aldehydes gives only products of reaction at the amino group; the structures of the resulting compounds depend on the reactivity of the carbonyl component.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1515–1522, November, 1981.     

Purine N-oxides—LII: ESR studies on photochemically induced radicals from N-hydroxyxanthines

UV, gamma-, or X-irradiation of several N-hydroxyxanthines as powdered solids produces radicals that are indefinitely stable in the solid state at room temperature, but are highly unstable in protic solvents. The ESR spectra are not sufficiently resolved to be definitive but are compatible with an amidogen radical, the unpaired electron of which is partially delocalized through the aromatic π system. Structural characterization was obtained by comparing the UV induced radicals from 3-hydroxyxanthine and 3-hydroxy-8-methylxanthine with chemically generated nitroxyl radicals from the same compounds. These two radical species show differences in their ESR spectra, in the extent of interaction of the unpaired electron with the methyl group at position 8, and in the products resulting upon reaction in water.The amidogen radical reacts instantaneously with water to yield the parent xanthines. Parallels are drawn between this reduction of the amidogen radical, the photoreduction of 3-hydroxyxanthine when solutions of it are irradiated with UV light, and the reduction of 3-acetoxyxanthine in aqueous solution in the absence of light.The synthesis of a requisite derivative, 3-hydroxy-7,8-dimethylxanthine, is reported.     

Synthesis, methylation, and acylation of 1,2-dihydrodeoxyvasicinones and their homologs

2,3-Trimethylene- and 2,3-pentamethylene-1,2,3,4-tetrahydro-4-quinazolones and their 6-methyl and 6-bromo derivatives have been obtained by the reduction of deoxyvasicinone and its 6-methyl and 6-bromo derivatives and also their seven-membered homologs at the cycloalkane ring with sodium tetrahydroborate in ethanol. The alkylation and acylation reactions of the above-mentioned reducing compounds have been studied.Institute of Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 659–663, September–October, 1990.     

Synthesis,methylation, and acylation of 1,2-dihydrodeoxyvasicinones and their homologs

2,3-Trimethylene- and 2,3-pentamethylene-1,2,3,4-tetrahydro-4-quinazolones and their 6-methyl and 6-bromo derivatives have been obtained by the reduction of deoxyvasicinone and its 6-methyl and 6-bromo derivatives and also their seven-membered homologs at the cycloalkane ring with sodium tetrahydroborate in ethanol. The alkylation and acylation reactions of the above-mentioned reducing compounds have been studied. Institute of Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 659–663, September–October, 1990.     

Rearrangements of 1-oxa-2-azoles 9. Rearrangements of hydrazidoximes of 1,2,4-oxadiazole-3-carboxylic acid

Reactions of acid chlorides of 1,2,4-oxadiazole-3-carbohydroximic acids with hydrazines lead to the formation of unstable hydrazidoximes, which readily undergo rearrangement to hydrazinofurazans. In the reaction with 4-nitrophenylhydrazine, the parallel reaction, leading to the formation of the amidrazone which undergoes rearrangement to the diaminotriazole, also proceeds simultaneouslyFor Communication 8, see [1]Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 969–973, July, 1992.     

Preparation and some reactions of 3-oxazoline N-oxides

Substituted 3-oxazolines react with m-chloroperoxybenzoic acid to give the corresponding 3-oxazoline N-oxides. These heterocyclic nitrones underwent molecular rearrangements, but would not react with 1,3-cyclo-addition type reagents.