R 12 Racemization of 4-aryl-amino-2-phtalimidoglutarates [Text] / V. P. Krasnov, M. A. Koroleva, I. M. Bukrina, I. A. Nizova, N. G. Evstigneeva // Amino Acids. - 1995. - Vol. 7, N 1. - P71-72 Рубрики: ХИМИЧЕСКИЕ НАУКИ |
A 18 Acidic hydrolysis of N-acyl-1-substituted 3-amino-1,2-dicarba-closo-dodecaboranes [Electronic resource] / G. L. Levit, A. M. Demin, M. I. Kodess, M. A. Ezhikova, L. Sh. Sadretdinova, V. A. Ol'shevskaya, V. N. Kalinin, V. P. Krasnov, V. N. Charushin // Journal of Organometallic Chemistry. - 2005. - Vol. 690, № 11. - P2783-2786 Рубрики: ХИМИЧЕСКИЕ НАУКИ Аннотация: Acidic hydrolysis of N-acyl 1-methyl- and 1-phenyl-3-amino-1,2-dicarba-closo-dodecaboranes has been studied. It has been shown that acidic hydrolysis of diastereomeric amides of 1-methyl-3-amino-1,2-dicarba-closo-dodecaborane results in the partial racemization of the target 3-amino-1-methylcarborane. Under the similar conditions, the hydrolysis of N-acyl-3-amino-1-phenyl-1,2-dicarba-closo-dodecaboranes resulted in amide bond cleavage accompanied by simultaneous deboronation with the removal of boron atom at position 6 of carborane cage and formation of 7,8-dicarba-nido-undecaborane derivative according to 11B and 1H NMR spectroscopy. \\\\Expert2\\nbo\\Journal of Organometallic Chemistry\\2005, v. 690, p.2783.pdf |
S 98 Synthesis of 4-amino derivatives of 5-oxoproline [Text] / V. P. Krasnov, A. Yu. Vigorov, I. A. Nizova, T. V. Matveeva, A. N. Grishakov, I. V. Bazhov, A. A. Tumashov, M. A. Ezhikova, M. I. Kodess // European Journal of Organic Chemistry. - 2007. - № 25. - P4257-4266 Рубрики: ХИМИЧЕСКИЕ НАУКИ Аннотация: The possibility of obtaining the stereoisomeric derivatives of 5-oxoproline and glutamic acid with a tertiary amino group at C-4, using the nucleophilic substitution of bromine in dimethyl (2S,4RS)-4-bromo-N-phthaloylglutamate with secondary amines followed by resolution of diastereomers and removal of protecting groups has been studied. We have shown that the reaction with arylamines results in optically pure 5-oxoproline derivatives in high yields. In the case of more basic amines, the reaction is accompanied by racemization, and the target products can be isolated only as diastereomeric racemates. |
E 54 Enantiomers of 3-amino-1-methyl-1,2-dicarba-closo-dodecaborane [Text] / V. P. Krasnov, G. L. Levit, V. N. Charushin, M. I. Kodess, V. N. Kalinin, O. N. Chupakhin // Tetrahedron: Asymmetry . - 2002. - Vol. 13, № 16. - P1833-1835. - Bibliogr. : p. 1835 (6 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Аннотация: The enantiomers of 3-amino-1-methyl-1,2-dicarba-closo-dodecaborane were prepared by means of resolution of the racemic mixture via acylation by (S)-naproxen chloride followed by separation and subsequent acid hydrolysis of each of the diastereoisomeric amides. Partial racemization of enantiomeric 3-aminocarboranes was observed during acid hydrolysis \\\\Expert2\\nbo\\Tetrahedron Asymmetry\\2002, v.13, p.1833.pdf |
1H NMR evidence for 5(4H)-oxazolones formation and racemization [Text] : доклад, тезисы доклада / O. N. Chupakhin, V. P. Krasnov, A. M. Demin, G. L. Levit, M. I. Kodess // XXth European Colloquium on Heterocyclic Chemistry, Stockholm,Sweden, 18-21 Aug. 2002 г. - Stockholm, 2002. - C:2 Рубрики: ХИМИЧЕСКИЕ НАУКИ |
S 90 Study of the effect of the nature of the side chain in esters of amino acids on the diastereoselectivity of condensation with 5(4H)-oxazolone in the synthesis of dipeptides with N-terminal N-acetylphenylalanine [Electronic resource] / V. P. Krasnov, E. A. Zhdanova, N. Z. Solieva, L. Sh. Sadretdinova, I. M. Bukrina, A. M. Demin, G. L. Levit, M. A. Ezhikova, M. I. Kodess // Russian Chemical Bulletin (Translation of Izvestiya Akademii Nauk, Seriya Khimicheskaya). - 2004. - Vol. 53, № 6. - P1331-1334 Рубрики: ХИМИЧЕСКИЕ НАУКИ Аннотация: Conditions for fast racemization of 5(4H)-oxazolones prepared from N-acylphenylalanine were found. Reactions of 4-benzyl-2-methyl-5(4H)-oxazolone with amino acid esters proceed diastereoselectively to give predominantly dipeptides comprising R-phenylalanine. The diastereoselectivity increases with complication of the structure of the side chain in the amino acid esters \\\\Expert2\\nbo\\Russian Chemical Bulletin\\2004, 53 (6), 1331.pdf |
S 90 Study of the inf luence of the alkyl ester group in (S)-valinates on diastereoselectivity of their condensation with N-acetylphenylalanine by the mixed anhydride method [Electronic resource] / E. A. Zhdanova, N. Z. Solieva, L. Sh. Sadretdinova, M. A. Ezhikova, M. I. Kodess, V. P. Krasnov // Russian Chemical Bulletin (Translation of Izvestiya Akademii Nauk, Seriya Khimicheskaya). - 2006. - Vol. 55, № 5. - P925-927. - Bibliogr. : p. 927 (15 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): 5(4H)-OXAZOLONES -- AMINO ACIDS -- DIASTEREOSELECTIVITY -- DIPEPTIDES -- DYNAMIC KINETIC RESOLUTION -- RACEMIZATION Аннотация: The dynamic kinetic resolution in the synthesis of alkyl N-acetylphenylalanyl (S)-valinates was studied by the mixed anhydride method. The structure of the ester group of the amino component appeared to exert no substantial effect on the diastereoselectivity of the reaction. \\\\Expert2\\nbo\\Russian Chemical Bulletin\\2006, 55 (5), 925.pdf |
S 98 Synthesis of derivatives of the RGD peptide with the residues of glutaric and adipic acids [Electronic resource] / A. Yu. Vigorov, I. A. Nizova, V. P. Krasnov, A. M. Demin // Russian Journal of Bioorganic Chemistry. - 2014. - Vol.40, №2. - С. 142-150. - Bibliogr. : p. 149-150 (42 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): AMINO ACIDS -- PEPTIDE SYNTHESIS -- RACEMIZATION Аннотация: Derivatives of the RGD peptide were prepared by the attachment of the residues of glutaric and adipinic acids to the α-amino group of L-arginine. This modification allowed condensation of these derivatives with other biomolecules or nanoparticles \\\\expert2\\nbo\\Russian Journal of Bioorganic Chemistry\\2014, v.40, N 2, p.142-150.pdf |
S 83 Stereochemical aspects in the synthesis of novel N-(purin-6-yl)dipeptides as potential antimycobacterial agents / V. V. Musiyak, I. A. Nizova, E. N. Chulakov [et al.] // Amino Acids. - 2021. - Vol. 53, № 3. - P407-415 Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): DIPEPTIDES -- RACEMIZATION -- PURINE -- COUPLING -- NUCLEOPHILIC SUBSTITUTION -- ANTIMYCOBACTERIAL ACTIVITY Аннотация: The synthesis of purine conjugates with natural amino acids is one of the promising directions in search for novel therapeutic agents, including antimycobacterial agents. The purpose of this study was to synthesize N-(purin-6-yl)dipeptides containing the terminal fragment of (S)-glutamic acid. To obtain the target compounds, two synthetic routes were tested. The first of them is based on coupling of N-(purin-6-yl)-(S)-amino acids to dimethyl (S)-glutamate in the presence of carbodiimide coupling agent followed by the removal of ester groups. However, it turned out that this coupling process was accompanied by racemization of the chiral center of N-(purin-6-yl)-α-amino acids and in all cases led to mixtures of (S,S)- and (R,S)diastereomers (6:4). Individual (S,S)-diastereomers were obtained using an alternative approach based on the nucleophilic substitution of chlorine in 6-chloropurine or 2-amino-6-chloropurine with corresponding dipeptides as nucleophiles. The enantiomeric purity of the target compounds was confirmed by chiral HPLC. To test the assumption that racemization of the chiral center of N-(purin-6-yl)-α-amino acids occurs with the participation of nitrogen atoms of the imidazole ring via the stage of formation of a chirally labile intermediate, we obtained such structural analogs of N-(purin-6-yl)-(S)-alanine as N-(9-benzylpurin-6-yl)-(S)-alanine and N-(7-deazapurin-6-yl)-(S)-alanine. It was found that coupling of these compounds to dimethyl (S)-glutamate was also accompanied by racemization. This indicates that the imidazole fragment does not play a crucial role in this process. When testing the antimycobacterial activity of some of the obtained compounds, conjugates with moderate activity against the laboratory Mycobacterium tuberculosis H37Rv strain (MIC 3.1–6.25 μg/mL) were identified. |