- ANALGESICS AND METHODS OF USE THEREOF
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The present invention relates to peptides with alternating stereochemistry. In particular, the invention relates to peptides comprising alternating stereochemistry of (LDLD) in the first four amino acid residues. The invention further contemplates the use of peptides with alternating stereochemistry in treating pain.
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Paragraph 00422
(2019/12/25)
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- Glycosylation of α-amino acids by sugar acetate donors with InBr 3. Minimally competent Lewis acids
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A simplified method for the preparation of Fmoc-serine and Fmoc-threonine glycosides for use in O-linked glycopeptide synthesis is described. Lewis acids promote glycoside formation, but also promote undesired reactions of the glycoside products. Use of 'minimally competent' Lewis acids such as InBr 3 promotes the desired activation catalytically, and with greatly reduced side products from sugar peracetates.
- Lefever, Mark R.,Szab, Lajos Z.,Anglin, Bobbi,Ferracane, Michael,Hogan, Joanna,Cooney, Lauren,Polt, Robin
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scheme or table
p. 121 - 125
(2012/05/20)
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- Serine and threonine Schiff base esters react with β-anomeric peracetates in the presence of BF3·Et2O to produce β-glycosides
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Improved procedures are reported for the glycosylation of L-serine and L-threonine utilizing activated Schiff base glycosyl acceptors, which are less expensive and more efficient alternatives to published methods. L-serine or L-threonine benzyl ester hydrochloride salts were reacted with the diarylketimine bis-(4-methoxyphenyl)-methanimine in CH3CN at rt to form the more nucleophilic Schiff bases 3a and 3b in excellent yield. These Schiff bases exhibited ring-chain tautomerism in CDCl3 as shown by 1H NMR. Schiff bases 3a and 3b, acting as glycosyl acceptors, reacted at rt with simple sugar peracetate donors with BF3·OEt 2 promotion to provide the corresponding L-serine and L-threonine O-linked glycosides in excellent yields and purities. The dipeptide ester Schiff base Ar2C = N-Ser-Val-OCH3 3e also reacted to provide β-glycosides in excellent yields, and without epimerization. With microwave irradiation the reactions were complete in 2 to 5 min. To investigate this reaction further, classical AgOTf-promoted Koenigs-Knorr reaction of D-glucopyranosyl, lactosyl, and maltosyl bromides were examined, providing the β-glycosides with yields ranging from 35% to 68%. The difference in reactivity between α- and β-carbohydrate peracetate donors was remarkable. The less configurationally stable D-xylopyranosyl tetra-acetate (a pentose) showed no selectivity (αvsβ-configuration) toward the Schiff bases. Copyright Taylor & Francis Group, LLC.
- Keyari, Charles M.,Polt, Robin
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p. 181 - 206
(2011/04/23)
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- Facile synthesis of glycosylated Fmoc amino acid building blocks assisted by microwave irradiation
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The synthesis of glycosylated Fmoc amino acids by reaction of mono- and disaccharide peracetates with Fmoc amino acids having free carboxyl groups was rapidly promoted by Lewis acids (SnCl4, BF3·Et 2O) under microwave irradiation. The products are useful building blocks for the synthesis of glycopeptides.
- Yao, Nianhuan,Fung, Gabriel,Malekan, Hamed,Ye, Long,Kurth, Mark J.,Lam, Kit S.
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experimental part
p. 2277 - 2281
(2010/11/19)
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- Solid-phase synthesis of O-linked glycopeptide analogues of enkephalin
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The synthesis of 18 N-α-FMOC-amino acid glycosides for solid-phase glycopeptide assembly is reported. The glycosides were synthesized either from the corresponding O'Donnell Schiff bases or from N-α-FMOC-amino protected serine or threonine and the appropriate glycosyl bromide using Hanessian's modification of the Koenigs-Knorr reaction. Reaction rates of D-glycosyl bromides (e.g., acetobromoglucose) with the L- and D-forms of serine and threonine are distinctly different and can be rationalized in terms of the steric interactions within the two types of diastereomeric transition states for the D/L and D/D reactant pairs. The N-α-FMOC-protected glycosides [monosaccharides Xyl, Glc, Gal, Man, GlcNAc, and GalNAc; disaccharides Gal-β(1-4)-Glc (lactose), Glc-β(1-4)-Glc (cellobiose), and Gal-α(1-6)-Glc (melibiose)] were incorporated into 22 enkephalin glycopeptide analogues. These peptide opiates bearing the pharmacophore H-Tyr-c[DCys-Gly-Phe-DCys]- were designed to probe the significance of the glycoside moiety and the carbohydrate-peptide linkage region in blood-brain barrier (BBB) transport, opiate receptor binding, and analgesia.
- Mitchell,Pratt,Hruby,Polt
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p. 2327 - 2342
(2007/10/03)
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