Synthesis and evaluation of novel pyridine based PLG tripeptidomimetics.

Analogues of the pyridine based PLG (Pro-Leu-Gly-NH(2)) peptidomimetic were synthesized and evaluated as dopamine modulating agents. Modifications in the position corresponding to the leucine side chain in PLG afforded derivatives , and , substituted with H, Me and Bn instead of the isobutyl group, respectively. Changes in the proline residue produced derivative , substituted with a symmetrical piperidine ring instead of the pyrrolidine ring and , in which the pyrrolidine ring is connected to the pyridine ring via a hydroxymethyl group instead of a keto function.

Synthesis of a C-glycoside analogue of beta-D-galactosylthreonine.

A C-linked analogue of beta-D-galactosylthreonine has been prepared from 2,3,4,6-tetra-O-benzyl-D-galactopyranolactone (1) in 14 steps. Three stereogenic centers were created during the synthesis, with the anomeric center of the C-glycoside being generated first by addition of a Grignard reagent to 1 and subsequent reduction of the intermediate hemiacetal with triethylsilane. The two stereogenic centers in the threonine moiety were both established by alkylation of Evans' chiral N-acyloxazolidinone enolates.