Synthesis of (±)-biotin from a substituted 2,3-dehydrothiophane

(±)-Biotin has been synthesized from a mixture of cis- and allo-trisubstituted dehydrothiophanes by a scheme providing for the easy elimination of the accompanying allo-substituted thiophane in the form of an intermediate and not as the final isomeric allo-biotin. The imidazoline ring of biotin is formed from a dialkoxy-carbonyldiaminothiophane under the conditions of partial hydrolysis of one of the protective groups with the elimination of phosgene from the scheme of synthesis.All-Union Scientific-Research Vitamin Institute, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 220–223, March–April, 1981.     

Synthesis of oxazolidine analogs of biotin and epibiotin

dl-cis- and dl-trans-6-(4-Carboxybutyl)-2-oxo-cis-hexahydrothieno[3,4-d]oxazoles were synthesized by the action of phosgene on r-4-amino-c-3-hydroxy-c(or, respectively, )-2-(4-carboxybutyl)thiophan hydrohalides. It is shown that the acid hydrolysis of r-4-benzamido-t-3-hydroxy-c(or t)-2-(4-methoxycarbonylbutyl)thiophans is accompanied by inversion to give r-4-amino-c-3-hydroxy-c(or t)-2-(4-alkoxycarbonylbutyl)thiophans.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 459–465, April, 1976.     

Thermal destruction of coordination polymers with an inorganic basic chain

Conclusions The destruction of coordination polymers based on diphenylarsenic, diphenylphosphinic, and p-toluenesulfonic acids was studied by the method of thermogravimetry in an inert atmosphere. Manganese polysulfonate possesses the greatest thermal stability.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2586–2588, 1969.     

Stereospecific synthesis of all of the possible isomers of 4-ureido-3-hydroxy-2-(5′-alkoxycarbonylbutyl)thiophan

All four possible isomers of 4-ureido-3-hydroxy-2-(5-alkoxycarbonylbutyl)-thiophan were synthesized by the action of potassium isocyanate on the corresponding hydrochlorides (or hydrobromides) of the stereoisomers of A-amino-3-hydroxy-2[5-methoxy (or ethoxy)carbonylbutyl]thiophans, which were obtained by several methods. The configurations of the compounds obtained were proved by PMR spectroscopy.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 616–620, May, 1980     

Quantum chemistry studies of far-infrared spectra of aromatic urethanes

Restricted Hartree-Fock and density function calculations (B3LYP), using 6-311++G(d,p), have been used to investigate the far infrared spectra of aromatic urethanes, synthesized on the basis of 2,4-and 2,6-toluene diisocyanate (2,4-TDI, 2,6-TDI), and the spectrum of ethylphenylurethane. It is shown, that the region of frequencies of 100-200cm(-1) is associated primarily with torsional vibrations of methyl groups. For almost all studied urethanes, the bands are observed in the region 385-340cm(-1), which is associated with in plane deformations of angles CCNC, COC and CNC of the urethane groups according to the calculations. The bands, observed at 300-320 and 260-280cm(-1), are assigned to in plane and out of plane deformations of the urethane skeleton, which are mixed with vibrations of methyl group connected to the benzene ring.     

13C NMR spectra and three-dimensional structures of isomeric 3,4-substituted thiophans

The chemical shifts and the direct carbon-proton spin-spin coupling constants for a number of cis and trans isomers of 4-amino-substituted 3-hydroxy(acyloxy)-thiophans, the configurations of the substituents in which and the conformational states were previously established by an independent method, were studied. It was found that in the spectra of the cis isomers the signals of the vicinal ¹³C atoms, which bear the substituents, are shifted to strong field as compared with the trans isomers ( trans-cis 1.7–4.3 ppm). Conformational effects of the substituents on the chemical shifts of the ring ¹³C atoms were noted. It is shown that a relationship exists between the direct carbon-proton spin-spin coupling constants and the spatial orientations of the acyloxy and acylamino substituents for five-membered saturated rings.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1612–1616, December, 1981.     

Dissociative ionization of fusidic acid and the products of its thermolysis in the temperature range of 30–250°C

The results are reported of a study of the dissociative ionization of fusidic acid and its derivatives, and also of an investigation of the products of its thermal degradation by the mass-spectrometric method. A scheme of fragmentation of the antibiotic under the action of electron impact is suggested.All-Union Scientific-Research Institute of Antibiotics, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 228–234, March–April, 1981.     

Oxidation of fusidic acid

Summary 11-Oxofusidic acid — a previously unknown keto derivative of the antibiotic — has been isolated from the products of the oxidation of fusidic acid by chromium trioxide.All-Union Scientific-Research Institute of Antibiotics, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 66–69, January–February, 1979.     

Influence of the type and concentration of a dopant on the dynamics of the beta-induced variation in the microhardness of silicon

The influence of the type and concentration of a dopant (P, Sb, B) on the dynamics of the transformation of a system of structural (intrinsic and radiation-induced) defects of silicon under low-intensity electron irradiation is investigated. A qualitative model is proposed for the formation of the complexes of secondary radiation defects responsible for the maxima of beta-induced softening of silicon single crystals.