Stereoselective synthesis of allyl- and homoallylglycines

Identification of novel low molecular weight CXCR4 antagonists by structural tuning of cyclic tetrapeptide scaffolds

A highly potent CXCR4 antagonist, compound 2, was previously found by using two orthogonal cyclic pentapeptide libraries involving conformation-based and sequence-based libraries based on the pharmacophore of a 14-mer peptidic antagonist, 1. Herein, cyclic tetrapeptides derived from replacements of the dipeptide unit (Nal-Gly) with a gamma-amino acid and pseudopeptides cyclized by disulfide and olefin bridges were synthesized to find novel scaffold structures different from that of cyclic pentapeptides. These compounds contain a reduced number of peptide bonds compared to compound 2. Furthermore, several analogues with chemical modification of the side chain of Arg(4) in 2 were also prepared. From these, several new leads possessing high to moderate CXCR4-antagonistic activity were characterized.

Synthesis of 5/7-, 5/8- and 5/9-bicyclic lactam templates as constraints for external beta-turns

The 5/7-, 5/8- and 5/9-bicyclic lactams 3, 17, 5 and 6 have been synthesised as single diastereoisomers by a route involving ring closing olefin metathesis. The X-ray crystal structure of the amino acid hydrochloride has been carried out and compared to that of the saturated external beta-turn constraint 18.

Systematic Study of the Synthesis of Macrocyclic Dipeptide β-Turn Mimics Possessing 8-, 9-, and 10- Membered Rings by Ring-Closing Metathesis

[structures: see text] A systematic study was performed to establish general synthesis protocols for forming enantiomerically pure macrocyclic dipeptide lactams. Focusing on macrocycles of 8-, 9-, and 10-membered rings, effective syntheses were achieved by a sequence featuring peptide coupling of allyl- and homoallyl-glycine building blocks followed by ring-closing metathesis. The 8-membered lactam-possessing cis-amide and cis-olefin geometry as well as 9-membered [corrected] lactams having trans-amide and cis-olefin [corrected] configurations were effectively prepared by a general strategy employing the respective protected dipeptide, the first generation Grubbs' catalyst, and temporary protection of the central amide as a benzyl derivative. The 10-membered macrocycle was synthesized possessing cis- or trans-olefin geometry by employing similar metathesis conditions in the presence or absence of temporary benzyl amide protection, respectively [corrected]

Synthetic applications of aliphatic unsaturated α-H-α-amino acids

This article provides an overview of the literature concerning synthetic applications of unsaturated aliphatic amino acids in the period May 2000 to December 2004.