Further Development of New Deprotection Chemistry for Cysteine and Selenocysteine Side Chain Protecting Groups

2009 ◽  
pp. 135-136 ◽  
Author(s):  
Alayne L. Schroll ◽  
Robert J. Hondal
Keyword(s):  
Protecting Groups ◽  
Side Chain ◽  
Further Development

Zur Totalsynthese des Human-Big-Gastrins I und seines 32-Leucin-Analogons (Vorläufige Mitteilung) / Total Synthesis of Human Big Gastrin I and the 32-Leucine Analogue (Preliminary Communication)

1977 ◽  
Vol 32 (7-8) ◽  
pp. 495-506 ◽  
Author(s):  
E. Wünsch ◽  
G. Wendlberger ◽  
A. Hallett ◽  
E. Jaeger ◽  
S. Knof ◽  
...  
Keyword(s):  
Total Synthesis ◽  
Building Blocks ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Protecting Groups ◽  
Side Chain ◽  
Tertiary Alcohols ◽  
Synthetic Product ◽  
Preliminary Communication ◽  
Final Purification

A new total synthesis of the tetratriacontapeptide amide corresponding to the proposed primary structure of human big gastrin I is described. The synthetic route was based on the preparation of six suitably protected fragments, related to sequence 28 - 34, 23 - 27, 21 - 22, 15-20, 9 - 14, and 1 - 8, to be used as building blocks for the total synthesis. The protecting groups were selected according to the Schwyzer-Wünsch strategy of maximum side chain protection based on tertiary alcohols, also for the imidazol function of histidine. Subsequent assembly of the six fragments by three different pathways using the highly efficient Wünsch-Weygand condensation procedure to ensure minimum racemization, followed by deprotection of the synthetic products via exposure to trifluoroacetic acid and final purification by ion-exchange chromatography on DEAE-Sephadex A-25 and partition chromatography on Sephadex G-25, led to human big gastrin I, homogeneous within the limits of the analytical methods used. The biological activity of the synthetic product proved to be 50 percent higher than that of human little gastrin I. The 32-leucine analogue of human big gastrin I was prepared in the same way.

Synthesis of the 5-Fluoro-4-hydroxypentyl Side Chain Metabolites of Synthetic Cannabinoids 5F-APINACA and CUMYL-5F-PINACA

Synthesis ◽  
2018 ◽  
Vol 50 (23) ◽  
pp. 4683-4689 ◽  
Author(s):  
Mark Trudell ◽  
Ryan McKinnie ◽  
Tasneam Darweesh ◽  
Phoebe Zito ◽  
Terrell Shields
Keyword(s):  
Efficient Method ◽  
Synthetic Cannabinoids ◽  
Synthetic Cannabinoid ◽  
Protecting Groups ◽  
Side Chain ◽  
Hydroxy Metabolites

An efficient method for the construction of the 5-fluoro-4-hydroxypentyl side chain common to a number of synthetic cannabinoid metabolites was developed. A series of hydroxyl protecting groups was examined to assess the viability as orthogonal protecting groups for epoxidation and regioselective hydrofluorination. The 1-[5-fluoro-4-(diphenyl-tert-butylsilyloxy)]pentyl tosylate was prepared in 67% overall yield (six steps) from pent-4-en-1-ol and was employed for the synthesis of the 4-hydroxy metabolites of the synthetic cannabinoid 5F-APINACA and CUMYL-5F-PINACA.

scholarly journals Structural Analysis of The OXA-48 Carbapenemase Bound to A “Poor” Carbapenem Substrate, Doripenem

Antibiotics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 145 ◽  
Author(s):  
Krisztina M. Papp-Wallace ◽  
Vijay Kumar ◽  
Elise T. Zeiser ◽  
Scott A. Becka ◽  
Focco van den Akker
Keyword(s):  
Public Health ◽  
Crystal Structure ◽  
Salt Bridge ◽  
Hydrolytic Activity ◽  
Van Der Waals Interactions ◽  
Side Chain ◽  
Carbapenem Resistant ◽  
Mechanistic Basis ◽  
Further Development ◽  
Carbapenem Resistant Enterobacteriaceae

Carbapenem-resistant Enterobacteriaceae are a significant threat to public health, and a major resistance determinant that promotes this phenotype is the production of the OXA-48 carbapenemase. The activity of OXA-48 towards carbapenems is a puzzling phenotype as its hydrolytic activity against doripenem is non-detectable. To probe the mechanistic basis for this observation, we determined the 1.5 Å resolution crystal structure of the deacylation deficient K73A variant of OXA-48 in complex with doripenem. Doripenem is observed in the Δ1R and Δ1S tautomeric states covalently attached to the catalytic S70 residue. Likely due to positioning of residue Y211, the carboxylate moiety of doripenem is making fewer hydrogen bonding/salt-bridge interactions with R250 compared to previously determined carbapenem OXA structures. Moreover, the hydroxyethyl side chain of doripenem is making van der Waals interactions with a key V120 residue, which likely affects the deacylation rate of doripenem. We hypothesize that positions V120 and Y211 play important roles in the carbapenemase profile of OXA-48. Herein, we provide insights for the further development of the carbapenem class of antibiotics that could render them less effective to hydrolysis by or even inhibit OXA carbapenemases.

scholarly journals Revisiting NO2 as Protecting Group of Arginine in Solid-Phase Peptide Synthesis

2020 ◽  
Vol 21 (12) ◽  
pp. 4464
Author(s):  
Mahama Alhassan ◽  
Ashish Kumar ◽  
John Lopez ◽  
Fernando Albericio ◽  
Beatriz G. de la Torre
Keyword(s):  
Peptide Synthesis ◽  
Solid Phase ◽  
Solid Phase Peptide Synthesis ◽  
Side Reaction ◽  
Reducing Agent ◽  
Protecting Groups ◽  
Side Chain ◽  
Protecting Group ◽  
Mild Acid

The protection of side-chain arginine in solid-phase peptide synthesis requires attention since current protecting groups have several drawbacks. Herein, the NO2 group, which is scarcely used, has been revisited. This work shows that it prevents the formation of δ-lactam, the most severe side-reaction during the incorporation of Arg. Moreover, it is stable in solution for long periods and can be removed in an easy-to-understand manner. Thus, this protecting group can be removed while the protected peptide is still anchored to the resin, with SnCl2 as reducing agent in mild acid conditions using 2-MeTHF as solvent at 55 °C. Furthermore, we demonstrate that sonochemistry can facilitate the removal of NO2 from multiple Arg-containing peptides.

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