Study of the inversion of 4-benzamido-3-hydroxythiophane

Inversion during the acid hydrolysis of trans-4-benzamido-3-hydroxythiophane is accomplished through the intermediate formation of cis-2-phenyltetrahydrothieno[3,4-d]oxazoline. The latter has cis ring fusion, and the oxazoline ring is planar. Opening of the oxazoline ring is not accompanied by inversion and leads to cis-3,4-substituted thiophanes. Migration of the acyl group from the nitrogen to the oxygen atom was detected in substituted thiophanes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No.10, pp. 1339–1344, October, 1971.     

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.     

Establishment of the configuration of 4-benzamido-3-oxo-2-(α-hydroxyamino-δ-carbomethoxybutyl)-thiophane

Proton magnetic resonance spectroscopy was used to establish that the addition of hydroxylamine to the exocyclic double bond of 4-benzamido-3-oxo-2-(-carbomethoxybutylidene)-thiophane occurs stereospecifically; the compound formed has the trans configuration with respect to the substituents in the 2 and 4 positions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1600–1601, December, 1972.     

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     

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.     

Stereospecific synthesis of cis- and trans-4-amino-3-hydroxythiophanes

The reduction of 4-benzoylamino- and 4-carbethoxyamino-3-ketothiophanes proceeds stereospecifically to form only trans-4-benzoylamino- and trans-4-carbethoxyamino-3-hydroxythiophanes, respectively, from which trans-4-amino-3-hydroxythiophane is obtained by alkaline hydrolysis. It was established that acid hydrolysis of trans-4-carbethoxyamino-3-hydroxythiophane leads only to trans-4-amino-3-hydroxythiophane, while acid hydrolysis of trans-4-benzoylamino-3-hydroxythiophane is accompanied by inversion to form cis-4-amino-3-hydroxythiophane. Derivatives of the cis- and trans-isomeric pairs of 4-amino-3-hydroxythiophanes were synthesized.Translated from Khimiya Geterotsilicheskikh Soedinenii, No. 12, pp. 1609–1613, December, 1970.     

Prototropic isomerization of trans-4-benzamido-3-hydroxy-2-(4-carbomethoxybutylidene)thiophan to cis- and trans-4-benza mido-3-oxo-2-(4-carbomethoxybutyl) thiophan

trans-4-Benzamido-3-hydroxy-2-(4-carbomethoxybutylidene)thiophan (I) was prototropically isomerized in the presence of hydrogen chloride. It is shown that the two possible isomers cis- and trans-4-benzamido-3-oxo-2-(4-carbomethoxybutyl)thiophan — are formed in the process.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No, 2, pp. 175–177, February, 1973.     

Advances in the chemistry of biotin

The review gives methods of synthesizing the biocatalyst biotin. The existing methods of obtaining biotin and its stereoisomers from dihaloalkanes, dicarboxylic acid esters, sugars, thiophene derivatives, etc., are discussed. The basic possibilities of the formation of biotin are considered.All-Union Scientific-Research Vitamin Institute. Translated from Khimiya Pridodnykh Soedinenii, No. 4, pp. 445–477, July–August, 1980.     

Formation of an acyclic disulfide from an 4-acylamino-3-oxothiophan

It has been established that 4-benzoylamino-3-oxothiophan is cleaved at a S-C bond by methanol in the presence of sodium methoxide with the formation of an acyclic disulfide.