Cycloaddition of α-dialkylborylamino-n-heterocycles to cyanamides

-Diisopropylaminopyridine and 2-dipropylborylamino-1-methylbenzimidazole react with cyanamides to give chelate [4+2]-cycloadducts. X-ray crystallography has been used to establish the molecular and crystal structure of the product of the reaction of -diisopropylaminopyridine and benzoylcyanamide.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 407–411, February, 1990.     

35Cl NQR study of CCl3 reorientations in the carbonyl-containing derivatives of 3,3,3-trichloropropene

Temperature dependences of³⁵Cl NQR frequencies and spin-lattice relaxation times were measured for the CCl₃ groups of compounds CCl₃CH=CHR and CCl₃CH=CR₂ with R=COCH₃ and COOCH₃. The activation energies of CCl₃ reorientations reflect the significant contribution of intermolecular steric interactions to the value of the potential barrier hindering these reorientations. In the CCl₃CH=CHCOCH₃ crystal, the reorientations of the CCl₃ group are hindered more than those of the molecule as a whole. Perm State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 35, No. 2, pp. 54–60, March–April, 1994. Translated by L. Smolina     

Synthesis of aza-, oxa-, and thiabicyclo[3.1.0]hexane heterocycles from a common synthetic intermediate

[reaction: see text] An efficient and stereospecific approach to the synthesis of structurally constrained aza-, oxa-, and thiabicyclo[3.1.0]hexane heterocycles has been achieved through application of the intramolecular cyclopropanation reaction of diazoacetates. The various constrained heterocycles (X = N, O, or S) are conveniently prepared from a common diol intermediate accessible from readily available cinnamyl alcohols. Application of the methodology to the synthesis of conformationally constrained oxazolidinone antibacterials is also discussed.     

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.     

A pulse radiolysis study of the reactions of the hydrated electron and hydroxyl radical with the oxalate ion in neutral aqueous solution

The rate constants of the reactions of e _aq ^? and the OH^· radical with the oxalate ion in a neutral aqueous solution were measured by means of the pulse radiolysis technique. They were found to be (3.5 ± 0.5) × 10⁷ and (1.5 ± 0.2) × 10⁷ l mol^?1 s^?1, respectively. The radical anion ^?OOC-C^·OO^2? is characterized by an optical absorption band that has a maximum at 270 nm and a molar absorption coefficient of (2400 ± 200) l mol^?1 cm^?1. The radical anion ^·OOC-COO^?, the product of the reaction with the OH^· radical, exhibits absorption that has no maximum and increases in intensity with a decrease in the wavelength extending to the UV region (?₂₂₀ = 1800 l mol^?1 cm^?1). The mechanism of radiation-chemical transformations in aqueous oxalate solutions is discussed.     

Reaction of β-aminopropionohydroxamic acid with aldehydes and ketones

β-Aminopropionohydroxamic acid reacts with aliphatic aldehydes or ketones to give 2-substituted 1-hydroxytetrahydropyrimidin-6-ones, while its reaction with aromatic carbonyl compounds leads to either the same products or Schiff's bases, which can exist in tautomeric equilibrium in solution. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 691–694, April, 1998.     

Pyrroloindoles. 6. New synthesis of 1H, 5H-pyrrolo[2,3-f]indole and 3H,6H-pyrrolo[3,2-e]indole

Ethyl pyruvate 1-acetyl-5-indolinylhydrazone was obtained by diazotization of 1-acetyl-5-aminoindoline with subsequent reduction of the diazonium salt and condensation of the hydrazine with ethyl pyruvate. A mixture of hydrogenated derivatives of linear and angular pyrroloindoles is formed as a result of cyclization of the hydrazone in polyphosphoric acid esters. Subsequent hydrolysis, decarboxylation, and dehydrogenation lead to 1H,5H-pyrrolo[2,3-f]indole and 3H,6H-pyrrolo-[3,2-e]indole.See [1] for Communication 5.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 504–507, April, 1982.