- Convergent Total Synthesis of the Siderophore Piscibactin as Its Ga3+Complex
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The siderophore piscibactin is a key virulence factor involved in the iron uptake of pathogenic bacteria Photobacterium damselae subsp. piscicida and Vibrio anguillarum, responsible for the fish diseases photobacterioisis (pasteurellosis) and vibriosis, respectively. A convergent total synthesis of its Ga3+ complex using l-/d-cysteine as chiral agents and Meldrum's acid is described. A Staudinger reduction/Aza-Wittig process in the synthesis of the acid-sensitive β-hydroxy-2,4-disubstituted thiazoline moiety and the convenient protecting groups was a key step in this synthesis.
- De La Fuente, M. Carmen,Jiménez, Carlos,Rodríguez, Jaime,Segade, Yuri,Valderrama, Katherine
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p. 340 - 345
(2021/01/13)
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- AN IMPROVED PROCESS FOR THE PREPARATION OF (1S, 4S, 7Z, 10S, 16E, 21R)- 7-ETHYLIDENE-4,21-BIS(1-METHYLETHYL)-2-OXA-12,13-DITHIA-5, 8, 20, 23- TETRAAZABICYCLO[8.7.6]TRICOS-16-ENE-3, 6, 9, 19, 22-PENTONE
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The present invention is relates to an improved process for the preparation (1S,4S,7Z,10S,16E,21R)-7-ethylidene-4,21-bis(1-methylethyl)-2-oxa-12,13-dithia-5,8,20,23-tetraazabi-cyclo[8.7.6]tricos-16-ene-3,6,9,19,22-pentone of formula I.
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Page/Page column 27
(2017/05/19)
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- Investigation of Cysteine as an Activator of Side-Chain N→S Acyl Transfer and Tail-to-Side-Chain Cyclization
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N→S Acyl transfer is a popular method for the postsynthesis production of peptide C α -thioesters for use in native chemical ligation and for the synthesis of head-to-tail cyclic peptides. Meanwhile thioester formation at the side chain of aspartic or glutamic acids, leading to tail-to-side-chain-cyclized species, is less common. Herein we explore the potential for cysteine to function as a latent thioester when appended to the side chain of glutamic acid. Initial insights gained through study of C-terminal β-alanine as a model for the increased chain length were ultimately applied to peptide macrocyclization. Our results emphasize the increased barrier to acyl transfer at the glutamic acid side chain and indicate how a slow reaction, facilitated by cysteine itself, may be accelerated by fine-tuning of the stereoelectronic environment..
- Castillo-Pazos, Durbis J.,Macmillan, Derek
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p. 1923 - 1928
(2017/09/13)
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- A comprehensive one-pot synthesis of protected cysteine and selenocysteine SPPS derivatives
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A proof-of-principle methodology is presented in which all commercially-available cysteine (Cys) and selenocysteine (Sec) solid phase peptide synthesis (SPPS) derivatives are synthesized in high yield from easily prepared protected dichalcogenide precursors. A Zn-mediated biphasic reduction process applied to a series of four bis-Nα-protected dichalcogenide compounds allows facile conversion to their corresponding thiol and selenol intermediates followed by insitu S- or Se-alkylation with various electrophiles to directly access twenty one known Cys and Sec SPPS derivatives. Most of these derivatives were able to be precipitated in crude form out of petroleum ether in sufficient purity for direct use as peptide building blocks. Subsequent incorporation of these derivatives into peptide models nicely illustrates their viability and applicability toward SPPS.
- Flemer, Stevenson
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p. 1257 - 1264
(2015/04/14)
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- Efficient procedure for the preparation of oligomer-free N-fmoc amino acids
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A two-step method is presented for the peptide-free, high-purity, and high-yield synthesis of N-Fmoc amino acids. The first step involves the preparation of stable dicyclohexylammonium-amino acid ionic adduct in acetone. Subsequently, the ionic adducts, on reaction with Fmoc-Nosu under mild alkaline conditions, give dipeptide-free N-Fmoc amino acids. The positive charge of the dicyclohexylammonium counterion in the ionic salt has a longer radius, moderating the nucleophilicity of the carboxylate ion of the amino acid and preventing by-products by arresting the formation of mixed anhydrides, the precursors of oligopeptide impurities.
- Nowshuddin, Shaik,Rao,Reddy, A. Ram
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experimental part
p. 2022 - 2031
(2009/11/30)
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- Treating disorders by application of insulin-like growth factors and analogs
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A method of enhancing the survival of neuronal cells in a mammal, the cells being at risk of dying, the method including the step of administering to the mammal one of the following substances: IGF-I; a functional derivative of IGF-I; IGF-II; a functional derivative of IGF-II; IGF-III; or a functional derivative of IGF-III.
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