Synthesis of a heptapeptide forming a modified ACTH 4–10 fragment

A scheme is given for the synthesis of a heptapeptide representing a modified ACTH 4–10 fragment on the basis of which it is possible to create a preparation that is an effective adaptogen of peptide nature. A proposed variant of the synthesis permits a peptide with an adequate degree of purity to be obtained comparatively simply on a larger scale. The intermediate compounds and the final products were obtained with good yields and were distinguished by chromatographic homogeneity. The heptapeptide synthesized did not differ with respect to its physicochemical characteristics and biological action from the analogous compound obtained previously. Some physicochemical characteristics of the compound obtained (angles of optical rotation, chromatographic mobilities) are given.     

Synthesis of a modified fragment 13–19 of the sequence of ACTH using silyl protection

A new scheme for the synthesis of a peptide representing a modified analog of fragments 13–19 of the sequence of the adrenocorticotropic hormone has been described, which uses a number of stages the trimethylsilyl grouping for the protection of the carboxy groups of amino acids and peptides. The final and intermediate products were obtained with high yields and were distinguished by chromatographic homogeneity.¹³C NMR was used as a supplementary method for the identification of the compounds. The physicochemical characteristics of the compounds synthesized are given.All-Union Scientific-Research Institute of the Technology of Blood Substitutes and Hormone Preparations, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 374–379, May–June, 1980.     

Protection of the carboxy group in the form of the 2-cyanoethyl ester in synthesis of peptides

With the aim of studying the suitability of the 2-cyano group for the protection of carboxylic functions in peptide synthesis, we have obtained the 2-cyanoethyl esters of a number of amino acids and have studied their behavior under the conditions of peptide synthesis. The synthesis of the pentapeptide leucine-enkaphalin has been performed with the use of 2-cyanoethyl protection for C-terminal carboxy groups throughout. The physicochemical characteristics of the compounds synthesized are given.All-Union Scientific-Research Institute of Molecular Biology Kol'tsovo, Novosibirsk oblast Vector Scientific Industrial Association of the USSR Minmedbioprom, Novosibirsk. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 412–416, May–June, 1988.     

Synthesis of a seven-membered analog of eledoisin using the solid-phase method of peptide synthesis

Summary 1. The solid-phase method of peptide synthesis has been used to obtain the heptapeptide HGly-L-Ala-L-Phe-L-Val-Gly-L-Leu-L-Met which is an analog of eledoisin.2. The possibility has been shown of using o-nitrophenylsulphenyl derivatives of amino acids in the solid-phase method of peptide synthesis.Khimiya Prirodnykh Soedinenii, Vol. 2, No. 3, pp 200–202, 1966     

Aromatic amino-claisen rearrangement in the synthesis of ellipticine

A convenient route is described for the preparation of 1,4-dimethylcarbazole — the key compound in the synthesis of the antitumoral alkaloid ellipticine. The interaction of 2,5-xylidine with 3-chlorocyclohexene led to N-(cyclohex-2-enyl)-2,5-xylidine (I), the two-hour heating of which at 140–150°C gave the product of an amino-Claisen rearrangement, 6-(cyclohex-2-enyl)-2,5-xylidine (II) with a yield of 82%. The intramolecular cyclization of compound (II) in polyphosphoric acid (130–140°C, 5 h) led to 5,6,7,8,12,13-hexahydro-1,4-dimethylcarbazole (III) in a yield of 75%. The dehydrogenation of substance (III) by boiling in trimethylbenzene in the presence of Pd/C gave 1,4-dimethylcarbazole (IV) with a yield of 87%. The conditions for performing the reactions and the physicochemical constants of the compounds obtained are given.Institute of Chemistry, Bashkir Scientific Center, Urals Branch, USSR Academy of Sciences, Ufa. Translated from Khimiya Prirodnykh Soedinenii, Vol. 6, pp. 816–818, November–December, 1989.     

Synthesis of a suggested aggression peptide

Four different schemes for the synthesis by the classical method of pyroglutamylasparaginylglycine — a suggested aggression peptide have been described. The best is a scheme using C- and N-terminal protective groups of the benzyl type at the stage of obtaining the protected tripeptide. Literature information according to which the compound possesses biological activity has been refuted.A. A. Zhdanov Leningrad State University. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 253–255, March–April, 1988.     

Preparation of hydrazides of amino acids and peptides

A new method of synthesizing hydrazides of amino acids and peptides is considered which involves the hydrazinolysis of the silyl esters of the corresponding compounds. A number of hydrazides of derivatives of amino acids and peptides has been obtained in high purity with yields close to quantitative. The physicochemical characteristics of the compounds synthesized are given.All-Union Scientific-Research Institute of the Technology of Blood Substitutes and Hormones Preparations, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 684–686, September–October, 1979.     

Synthesis and properties of a symmetrical macroheterocyclic compound containing 1,3,4-thiadiazole residues

A new macroheterocyclic, symmetrical compound containing 1,3,4-thiadiazole residues was synthesized, and several of its physicochemical properties are given.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 194–195, February, 1971.     

Use of pentafluorophenyl esters in the synthesis of intermediate fragments of ACTH

The results are given of the synthesis of the heptapeptide 13–19 of the natural sequence of ACTH using, in a number of stages, the pentafluorophyl esters of amino acids and peptides in combination with the temporary silyl protection of the carboxy group of the amino components. The intermediate compounds were obtained with good yields (70–90%) in chromatographically homogeneous form and their physicochemical characteristics did not differ from those of similar products obtained by other methods and described in the literature. The identification and checking of the purity of the compounds synthesized was carried out not only by traditional methods but also by the¹³C NMR method and by high-pressure liquid chromatography. Some physicochemical characteristics of the compounds synthesized are given.