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  • Author: Wolfgang Voelter x
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Benzyl 2,3-anhydro-4-0-triflyl-β-L-ribopyranoside (1) and benzyl 2,3-anhydro-4-O-triflyl-α-D-lyxopyranoside (3) react with pyridine to give benzyl 2,3-anhydro-4-deoxy-4-[N]-pyridinium - α-D-lyxopyranoside triflate (2) and benzyl 2,3-anhydro-4-deoxy-4-[N]-pyridinium -β-L-ribopyranoside triflate (4). Similar reactions with thiourea and dimethylsulfoxide are mentioned. Compound 2 is stable at room temperature, whereas compound 4 decomposes in a few hours (neighbouring group effect). The 13C NMR assignments of 2 are proved by 13C {1H} single frequency decoupling experiments.

Selected Topics. Proceedings of the Fall Meeting Gesellschaft für Biologische Chemie Tübingen, Germany, September 1979

A new synthesis for the tripeptide Pyr-Ser-Gly-NH,, with mutual GH-RH activity is described. Z-L-Pyr-OH is reacted with HO-NSu to the protected amino acid derivative Z-L-Pyr-ONSu. Further intermediates in the synthesis are Z-L-Pyr-L-Ser(Bzl)-OH and Z-L-Pyr-L-Ser(Bzl)-Gly-NH,.

Abstract

The 2.4.6-triisopropylbenzenesulfonyl group is introduced in high yield into the guanidino function of arginine by the reaction of Na-protected arginine with 2.4.6-triisopropylbenzene-sulfonyl chloride. This protecting group was found to be cleaved by commonly used reagents used in peptide synthesis like methanesulfonic, trifluoromethanesulfonic acid or mixtures of tri-fluoroacetic with methanesulfonic or trifluoromethanesulfonic acid.

New muramyl dipeptide derivatives with exchanged carbohydrate residues are described. Each derivative is synthesized via a solid phase synthesis using an aminomethyl anchor resin. All synthetic products can be isolated in good yields. Their biological activities are tested by the luminol-dependent chemiluminescence associated with the phagocytosis of opsonized zymosan by granulocytes.

As part of our total synthesis of thymosin β4 an optimized synthesis of the C-terminal part of thymosin β4 is described. Side chain functional residues of the tridecapeptide are masked by tert-butyl and the α-amino residues are protected by Z groups. The fully protected peptide derivative was obtained by WSCI/HOBt coupling of three fragments representing the segments [31-35], [36-37] and [38-43].

In previous communications1-4 substituent effects in the 1-arylisobenzpyrylium salt series were investigated. 13C NMR spectroscopy now made it possible to obtain quantitative data, which could be used for comparison of the electron distribution in 1-arylnaphthalene (1), 1-arylisobenzpyrylium salt (la), N-methylisoquinolinium salt (1b) and 1-arylisoquinoline (1c) derivatives. We hope that this set of data will be useful for the study of the differences in aromatic character in the various compounds and some insight into the interactions between the heterocyclic and the 1-aryl ring can also be obtained.