Synthesis of derivatives of 4-alkylthiouracil,cytosine, pyrido[2,3-d]pyrimidine,and pyrimido[4,5-d]pyrimidine from the N,S- and N,N-acetals of diacetylketene and isocyanates

The action of alkyl and aryl isocyanates on the N,S-acetals of diacetylketene leads to the formation of 4-alkylthio-5-acetyl-1-alkyl(aryl)-6-methyl-1H-pyrimidin-2-ones (derivatives of 4-alkylthiouracils). The reaction of the synthesized thiouracils with amines or the reaction of the N,N-acetals of diacetylketene (N,N-ADK) with an equi-molar amount of aryl isocyanates leads to the formation of substituted 4-amino-5-acetyl-1H-pyrimidin-2-ones (derivatives of cytosine). From the latter and isocyanates or directly from N,N-ADK and an excess of the isocyanate, derivatives of 4-methylene-1H,3H, 4H-pyrimido[4,5-d]pyrimidine-2,7-dione were obtained. The exception was the condensation of 3-[N-(4,6-dimethyl-2-pyrimidinyl)diaminomethylene]pentane-2,4-dione with aryl isocyanates, which led to 3H,8H-pyrido[2,3-d]pyrimidine-2,5-diones.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2593–2599, November, 1991.     

Reactions of 3-hydroxy-1,2-dihydroquinazolin-4-ones with acid chlorides

The reactions of 3-hydroxy-1,2-dihydroquinazolin-4-ones with acid chlorides can afford compounds of different types. The structures of the products depend on the type of acid chloride used and on the nature of the substituent at position 2 of the 3-hydroxy-1,2-dihydroquinazolin-4-one. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1346–1349, July, 1999.     

3-(1-Methyl-1-nitroethyl-1-<Emphasis Type="Italic">ONN</Emphasis>-azoxy)-4-aminofuroxan. Synthesis and transformations of the amino group

A four-step procedure to convert 4-(1-methyl-1-nitroethyl-1-ONN-azoxy)-3-cyanofuroxan into 3-(1-methyl-1-nitroethyl-1-ONN-azoxy)-4-aminofuroxan was developed. The pathways of transformation of the amino group of the synthesized compound into N-nitramino-, N-alkyl-N-nitramino-, N,N’-methylenediamino-, N,N’-methylene-N,N’-dinitramino-, and azo groups were studied.     

<Emphasis Type="Italic">N</Emphasis>-β-Nitroxyethyl derivatives of 1,1’-[methylenebis(oxy)]bis(triaz-1-ene 2-oxides)

Synthetic procedures towards new N-β-hydroxyethyl- and N-β-bromoethylated 1,1’-[methyl enebis(oxy)]bis(triaz-1-ene 2-oxides) were developed. N-β-Nitroxyethyl[methylenebis(oxy)]- bis(triaz-1-ene 2-oxides) were first synthesized by nitration of N-β-hydroxyethyl derivatives and nucleophilic substitution of the bromine atom of N-β-bromoethyl derivatives. The first representative of a new class of energetic compounds, namely, (1-nitroxymethoxy)triaz-1-ene 2-oxide, was synthesized.     

Oscillatory melting temperature of the vortex smectic phase in layered superconductors

We report on transport measurements of YBa 2Cu 3O (7-delta) single crystals with different oxygen contents in the geometry B, J ||ab (J perpendicularB). Our data show that the vortices become confined between the Cu-O planes below a well-defined temperature at which the effective size 2xi of the vortex core is approximately equal to the period of the Cu-O layers. This confinement strongly increases the vortex liquid freezing temperature. A new melting line is found separating a vortex liquid and a smectic phase, which shows an oscillatory field dependence reflecting differences between commensurate and incommensurate smectic states.     

Chelate synthesis of derivatives of 7-diaminomethylene-4,5,6,7-tetrahydro-2h-indazol-6-one

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 525–526, February, 1991.