Synthesis of the hexapeptide 11–16 of the natural sequence of human calcitonin

A new variant of the preparative synthesis of hexapeptide 11–16 of the natural sequence of human calcitonin is described. In several of the stages 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline was used successfully as the condensing agent. The final and intermediate compounds were obtained with good yields in chromatographically homogeneous form. Their purity was checked by TLC and measurements of angles of optical rotation. The final product was identified additionally by¹³C NMR. Several physicochemical characteristics of the compounds synthesized (angles of optical rotation, chromatographic mobilities) are given.     

6-(1,3-Dioxoindan-2-ylidenemethyl)-1,2,2,4-tetramethyl-1,2-dihydro- and 1,2,3,4-Tetrahydroquinolines

6-Formyl-1,2,2,4-tetraalkyldi- and -tetrahydroquinolines have been synthesized by the Vilsmeier reaction and they are readily condensed with 1,3-indanedione to give 2-hetarylidene-1,3-indanediones. The latter exist as complexes with charge transfer from the quinoid structure of the heterocyclic fragment.     

Use of tert-butoxycarbonyl protection in the synthesis of the peptide corresponding to sequence 17–19 of ACTH

The paper gives the results of the synthesis of the tripeptide arginyl-arginylproline performed with the use of various condensing agents. N-tert-Butoxycarbonyl-N-nitroarginine was used as the starting compound. Some physicochemical characteristics of the tripeptide derivatives (melting point, angle of optical rotation, elementary composition) are given. The¹³C NMR method was used to identify the structures of the compounds. The chemical shifts of the signals and their assignments 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. 373–378, May–June, 1979.     

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.     

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.