Preparation of 1-thioglycosides having ω-aldehydo aglycons useful for attachment to proteins by reductive amination

A series of 1-thioglycosides containing an ω-aldehydo group (as the dimethyl acetal) on the aglycon were prepared by reaction of O-acetyl-1-thioaldoses with N-(chloroacetyl)aminoacetaldehyde dimethyl acetal, a compound readily prepared by the action of chloroacetyl chloride or chloroacetic anhydride on 2-aminoacetaldehyde dimethyl acetal. O-Deacetylation of the 1-thioglycosides, followed by deacetalation, yielded the desired products. An analogous 1-thioglycoside having a longer aglycon was prepared by reaction of 1-thio-D-galactose with (6-aminohexanoyl)-aminoacetaldehyde dimethyl acetal, obtained by condensing 6-bromohexanoic acid and aminoacetaldehyde with 3-(3-dimethylaminopropyl)-1-ethylcarbodiimide. These glycosides were found to be useful for modification of proteins to yield neoglyco-proteins.