General method for the synthesis of N-methyl amino acids and N-alkyl amino esters from O'Donnell's Schiff bases
作者:Jason J. Chruma、Dalibor Sames、Robin Polt
DOI:10.1016/s0040-4039(97)01132-5
日期:1997.7
N-methyl aminoacids, including L-abrine, and N-alkylamino esters, were synthesized by reductive amination of O'Donnell's Schiff base amino esters with NaBH3CN and formaldehyde, or the appropriate aldehyde in CH3CN or THF in good to excellent yields, and with high purity.
Solid-Phase Synthesis of O-Linked Glycopeptide Analogues of Enkephalin
作者:Scott A. Mitchell、Matt R. Pratt、Victor J. Hruby、Robin Polt
DOI:10.1021/jo005712m
日期:2001.4.1
The synthesis of 18 N-alpha -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-alpha -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-alpha -FMOC-protected glycosides [monosaccharides Xyl, Glc, Gal, Man, GlcNAc, and GalNAc; disaccharides Gal-beta (1-4)-Gle (lactose), Glc-beta-(1-4)-Glc (cellobiose), and Gal-alpha (1-6)-Glc (melibiose)] were incorporated into 22 enkephalin glycopeptide analogues. These peptide opiates bearing the pharmacophore H-Tyr-c[DCys-Gly-PheDCys]- 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.
Stereoselective synthesis of β-d-glycopyranosyl-l-serinate or -threoninate derivatives with an unusual migration