SPIRODIKETOPIPERAZINES OF MANNOFURANOSE - CARBOPEPTOID ALPHA-AMINO-ACID ESTERS AT THE ANOMERIC POSITION OF MANNOFURANOSE

Epimeric mannofuranose anomeric aminoesters are prepared from readily available azidolactones and can act as building blocks for the incorpo ration of mannofuranose units into peptide chains [carbopeptoids]; alt ernative acylating conditions allow either rapid acylation of the more stable but kinetically hindered amine or reaction with the less hinde red but less stable amine to allow control of the anomeric configurati on of the products. This is exemplified by coupling of the aminoesters with glycine derivatives to give dipeptide equivalents, and subsequen t cyclization to spiro diketopiperazines, Anomers with the nitrogen fu nction cis to the 2,3-diol are more stable than those with nitrogen tr ans; mannofuranose derivatives are more stable than the mannopyranose isomers. (C) 1998 Published by Elsevier Science Ltd. All rights reserv ed.