Application of the method of chromatographic plates toΒ-dicarbonyl compounds

Summary The chromatographic behavior of-dicarbonyl compounds was investigated using as an adsorbent silica gel — starch fastened to a glass plate.     

Mechanism of cyclocondensation of isoprenoid acyclic α,Β-enals with monoethyl malonate under the conditions of the Knoevenagel reaction

It was shown that the formation of the di- and trisubstituted derivatives of 1.3-cyclohexadiene-1-carboxylic acid during the condensation of 3-methyl-2-butenal, citral, and farnesal with monoethyl malonate in the presence of secondary amines takes place through the enamines corresponding to these aldehydes, which add to the monoesters of the respective alkenylidenemalonic acids (the normal products of the Knoevenagel reaction) by a mechanism of [4 + 2]-cycloaddition. The free carboxyl group in the dienophile is required for the spontaneous transformation of the intermediate [4 + 2]-cycloadducts into the derivatives of cyclohexadiene-1-carboxylic acid in which the catalyst of the process (the secondary amine) is regenerated.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1079–1088, May, 1991.     

Synthesis of 5-hydroxy-6-methyluracil 3-Β-D-ribofuranoside

3-(-D-Ribofuranosyl)-5-hydroxy-6-methyluracil was synthesized by the silyl method in the presence of SnCl₄ using 1-O-acetyl-2,3,5-tri-O-benzoyl--D-ribofuranose as the carbohydrate component. The structures of the glycosides were confirmed by spectral methods.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 794–797, June, 1991.     

Molecular structures of syn- and anti-20-carboethoxyhydrazone isomers of 3Β, 21-diacetoxypregna-5,16-dien-20-one

The validity of syn- and anti-isomer assignments in the case of 3,21-diacetoxypregna-5, 16-dien-20-one 20-carboethoxyhydrazones has been established by x-ray structural analysis; the isomer designations had been made previously based on chemical and spectral data. The isomers differ sharply in the conjugative relationship between the hydrazone group and the C¹⁶=C¹⁷ double bond in the steroid skeleton: the syn-isomer is trans-conjugated (the degree of twisting about the C¹⁷-C²⁰ bond is characterized by a torsional angle=-161.0), while the anti-isomer is not conjugated (=– 75.3); this explains the electronic spectral features of these isomers.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 610–615, March, 1991.     

Reactions of 3-(Β-hydroxyethyl)-8-thiaxanthine

Depending on the base used, reaction of 3-(-hydroxyethyl)-8-thiaxanthine with p-toluenesulfonylchloride either stops at the stage of formation of the tosylate or gives 1,2,5-thiadiazolo[3,4-d]oxazolidino[2,3-b]pyrimidin-9(4H)-one. Upon treatment with ammonia or methylamine, both of these compounds react to give 3-(-hydroxyethyl)-8-thiaguanines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 272–274, February, 1991.     

Reactions of N-(Β-aminoethyl)piperazine and its derivatives

The alkylation, cyanoethylation, and heterocyclization reactoins of N-(-amonoethyl)piperazine and its derivatives, dicarboxylic acid imides, have been investigated. A new method has been proposed for the synthesis of 1,4-diazobicyclo[2.2.2]octane via pyrolytic cleavage of N,N-bis[piperazinoethyl]ethylenediamine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 381–385, March, 1991.     

Synthesis and transformations of the 20-substituted derivatives of 16α,17α-epoxy-5α-pregnane-3Β,21-diol-20-ones

A new and more effective sequence of reactions is proposed for the production of 16,17-isopropylidenedioxy-5-pregnane-3,21-diol-20-one. It uses methods previously unused for 5-H-steroids and involves 21-hydroxylation of 16,17-epoxy-5-pregnan-3-ol-20-one with diacetoxyiodobenzene and cis-opening of the obtained 21-hydroxy-16,17-epoxy-5-pregnane-3,21-diol-20-one by acetic acid in the presence of epoxycarbonylhydrazine, followed by condensation of the obtained product with acetone.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1185–1188, May, 1991.     

Transformed steroids. 185. Use of the Nicholas reaction for regio- and stereo-selective transformation of 16α,17a-epoxy-17Β-ethynyl-androstanes into 16α,17α-cis-disubstituted steroids

The HBF₄·Et₂O-catalyzed methanolysis reactions of the 16, 17-oxides of 17-ethy-nylandrost-4-en-3-one and its dicobalt hexacarbonyl complex were studied. It was shown that these reactions proceed with the same regiodirectivity of the oxide ring opening at the tertiary center but with a different mode of stabilization of the intermediates formed. The reaction of the free oxide proceeds without the inclusion of the external nucleophile and is concluded by the Wagner-Meerwein rearrangement; the C¹⁷-carbocation formed in the Co-coordinated oxide is stabilized by the addition of the methoxide ion and the elimination of a proton or of water. The opening of the oxide ring of dicobalt tetracarbonyl 16, 17-epoxy-17-ethynylandrost-4-en-3-one can be realized with decomplexation accompanied by carbonylation and heterocyclization.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp.1180–1184, May, 1991.     

Synthesis and cyclization of N-(2-hydroxyphenyl)-and N-(2-benzyloxyphenyl)-Β-alanines

N-Substituted -alanines have been synthesized by treating o-aminophenol or o-benzyloxyaniline with acrylic, methacrylic, or crotonic acids. Their cyclization to 2-benzoxazolinones and dihydro-2,4(1H,3H)-pyrimidinediones has been studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 527–531, April, 1991.     

Transformed steroids. 184. Pathways for the use of 17α-pregna-4,9-dien-3-on-17Β-ol-20-yne in the synthesis of 9, 11-disubstituted pregnanes

A study was carried out on pathways for the conversion of 17-pregna-4, 9-dien-3-on-17-ol-20-yne to 9, 11-epoxypregn-4-en-17-ol-3-on-20-ynes and their ^16– and 16, 17-epoxy derivatives, which are valuable intermediates in reported schemes for the synthesis of corticosteroids.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 724–729, March, 1991.     

Asymmetric synthesis of heteroorganic analogs of natural compounds. 3. General preparative method of diastereo- and enantioselective synthesis of fluorine-containing 2(R), 3(S)-Β-phenylserines

The diastereo- and enantioselective synthesis of the previously unknown 2(R), 3(S)--phenylserines containing fluorine atoms, the O-CHF₂-, O-CF₃-, and CF₃ groups in the benzene ring, was carried out by alkylation of a Ni(II) complex of a Schiff base of glycine with (S)-2-N-(N'-benzylprolyl)aminobenzophenone by fluorine-substituted benzaldehydes. The factors influencing the stereochemical result of the reactions studied are not the steric characteristics of the substituents in benzaldehydes, but their electronic nature.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1166–1175, May, 1991.     

Synthesis of esters of α-chloroacetoxy-β,β,β,-trichloroethylphosphonic acids

Summary The synthesis of 11 previously unreported dialkyl esters of -mono-, -di-, and -trichloroacetoxy-,,-trichloroethylphosphonic acids has been effected.