Synthesis of a Pseudotrisaccharide Suitable for Synthesis of Ring I Modified 4,5-2-Deoxystreptamine Type Aminoglycoside Antibiotics.

To facilitate the synthesis of paromomycin and/or neomycin analogs we describe a cleavage of ring I from paromomycin that proceeds in the presence of azides and affords a glycosyl acceptor for the installation of a modified ring I. A paromomycin 4',6'-diol is oxidized by the Dess-Martin periodinane followed by m-chloroperoxybenzoic acid. Base treatment then affords a protected pseudodisaccharide, which functions as a glycosyl acceptor. The method should also apply to the cleavage of a pyranosyl 4,6-diol from oligosaccharides and glycoconjugates.