Cycloaddition as a possible path to disaccharide synthesis: stereochemical course of the reaction of butyl glyoxylate with a chiral, protected dienyl ether of glucose

Abstract

The addition of 1,2:5,6-di-O-isopropylidene-α-D-glucofuranose (2) to 2,7-dimethylocta-3,6-diyne-2,7-diol (1) gave a mixture of cis-(3) and trans-(4) 3-but-1-en-3-ynyl ethers, which were separated and partially hydrogenated to give the corresponding dienyl ethers (5) and (6). These were also obtained by a Wittig reaction of the phosphorane derived from 1,2:5,6-di-O-isopropylidene-3-O-(triphenylphosphoniomethyl)-α-D-glucofuranose chloride (9) with acrylaldehyde. The reaction of butyl glyoxylate with the trans-diene gave principally the trideoxydisaccharide of cis-configuration (11).