α- and β-Homogalactonojirimycins (α- and β-Homogalactostatins): synthesis and further biological evaluation Original Research Article

The homoiminosugars α- and β-homogalactonojirimycins were prepared from a common intermediate, tetra-O-benzyl-d-galacto-heptenitol 6, by way of highly stereoselective reaction sequences involving, as the key steps, an internal amidomercuration (α-epimer) and a double reductive amination (β-epimer). α-Homogalactonojirimycin retains a large part of the potent activity of the parent galactonojirimycin and 1-deoxygalactonojirimycin as an inhibitor of α-galactosidases. However, by contrast with the parent iminosugars, it does not inhibit β-galactosidases, with the exception of the Jack beans enzyme. β-Homogalactonojirimycin is a weak α-galactosidase inhibitor and is completely devoid of activity towards β-galactosidases. Thus, a marked selectivity toward one family of enzymes has been achieved by the addition of an α-CH2OH group in the structure of the parent iminosugars.