An improved, high-yield synthesis of the corresponding N-carboxypentyl derivatives of three iminoalditol glycosidase inhibitors has been developed for affinity chromatography enzyme purification. Reductive amination of 1-deoxynojirimycin (or its D-manno or D-galacto analogues) with methyl 5-formylvalerate and NaBH3CN at neutral pH afforted an aminoester which upon hydrolysis with aqueous 5% HCl gave the desired aminoacid in 97% overall yield. These amino acids could then be covalently attached using water-soluble carbodi-imide to 6-aminohexyl Sepharose 4B.
