Synthesis of Bis-Glyoxylamide Peptidomimetics Derived from Bis-N-acetylisatins Linked at C5 by a Methylene or Oxygen Bridge

The bis-glyoxylamide peptidomimetics have been synthesized from bis-N-acetylisatins linked at C5 by ring-opening with alcohols, amines, and amino acid methyl ester hydrochlorides. X-ray images of single crystals of bis-glyoxylamide peptidomimetics have been obtained.

Crown Ether Ditopic Receptors for Ammonium Salts with High Affinity for Amino Acid Ester Salts

Two bis crown ether receptors were synthesized and tested as host molecules for protonated forms of alkyl amines and amino acid esters. Molecular recognition studies were conducted in CH2Cl2:MeOH (92:8) by spectrophotometric UV/Vis titrations andby spectrometric 1H NMR titrations in CDCl3. The calculated binding constants are in the range 102-105 M-1. A high affinity for L-amino acid methyl ester derivatives was found. A theoretical study at the DFT level of the synthesized receptor and some analog ligands with three different ammonium ions helps to rationalize the experimentally found trends.

Synthesis of Dipeptides by Boronic Acid Catalysis

We have found that a boronic acid catalyzed amidation of an N-hydroxy amino acid methyl ester with amino acid tert-butyl esters gave N-hydroxy dipeptide derivatives in good yields without any racemization. The protecting groups on the nitrogen atom could be easily removed by heterogeneous hydrogenation conditions.

Synthesis of d4T- 5′-glycosyl-1″-phosphoramidates from H-Phosphonates via an Oxidative Coupling Strategy

An improved synthetic method based on glycosyl-1-H-phosphonate diesters has been developed for the preparation ofO-d4T-5′-O-glycosyl-1″-phosphoramidate diesters, a kind of potential anti-HIV prodrugs. The target products were synthesized in high yields by using the CCl4/Et3N/amino acid methyl ester system.