Part 1. 2-Deoxy-C-glycofuranosides from D-glucose. Part 2. An approach to N-acetylneuraminic acid from carbohydrate precursors.

Abstract

Part 1: 4,6-0-Benzylidene methyl glucoside undergoes periodic oxidation resulting in a sesqui-acetal which may be regarded as a protected erythrose. The use of the Wittig reaction on this protected erythrose and similar derivatives to extend the number of carbons by one was studied. Ring closure under oxymercuration conditions should lead to C-l substituted 2- deoxyfuranosides. This short, convergent approach to C-glycofuranosides can be extended to C-nucleoside synthesis if the preparation of an appropriate heterocyclic Wittig reagent can be achieved. Part 2: N-Acetylneuraminic acid, a 9-carbon sugar, is the most abundant member in the sialic acid family. Retrosynthetic analysis shows C-3, C-4 bond disconnection is logical. This synthetic strategy involves: 1. Synthesis of the fully protected mannosamine derivative: fully protected glucosamine was synthesized. 2. Stereoselective C3-C4 bond formation: model reactions were carried out and the desired threo β-amino alcohol was the major isomer in the product mixture. 3. Conversion of the 3-carbon nucleophile to an α keto ester or α keto acid: We have explored different oxidative conditions on model compounds.