INTRODUCTION DE MOTIFS ACIDES α,β-ETHYLENIQUES EN POSITION 5 OU 6 DE PENTOSIDES ET D'HEXOSIDES PAR REACTION DE HORNER

Abstract

A general synthesis of glycoconjugate α,β-ethylenic acid precursors of glycoenkephalines is described with the aim to further introduce a peptide moiety on a glucide to prepare glycoenkephalines. The Horner reaction between the lithiated dianions of 2-diethyl-phosphonoalcanoic acids and the terminal aldehyde of dialdoses lead to the expected α,β-ethylenic acids in good yields. The results are compared with those of the similar Horner reactions using the lithiated methyl 2-diethylphosphonoalcanoates as reagents. The two types of reagents are complementary, the dilithiated dianions generally lead predominantly to the E isomer whereas the lithiated monoanions derived from 2-diethylphosphonoalcanoates give mainly the Z isomer.

Key Words:

• α-Phosphonylated dianions
• dialdoses
• glycoconjugate
• α,β-ethylenic acids
• Horner reaction