TOTAL SYNTHESIS OF NEOMYCIN B

Article abstract of DOI:10.1016/0008-6215(88)85087-0

Total synthesis of neomycin B, a pseudo-tetrasaccharide aminoglycoside antibiotic, has been achieved through two key glycosylation reactions.Coupling of 3-O-acetyl-2,6-diazido-4-O-benzyl-2,6-dideoxy-L-idopyranosyl chloride with 5-O-benzoyl-1,2-O-isopropylidene-α-D-ribofuranose under modified Koenigs-Knorr conditions gave 70percent of the desired β-L disaccharide (3) and corresponding to neobiosamine in structure.After deisopropylidenation of 3 and acetylation, 1,2-di-O-acetyl-3-O-(3-O-acetyl-2,6-diazido-4-O-benzyl-2,6-dideoxy-β-L-idopyranosyl)-5-O-benzoyl-D-ribofuranose was coupled to HO-5 of 3,2',6'-tri-N-(benzyloxycarbonyl)-1-N:6-O-carbonyl-3',4'-di-O-(o-methoxybenzoyl)neamine, using trimethylsilyl trifluoromethanesulfonate, to give 60percent of the pseudo-tetrasaccharide 19 possessing the framework and masked functionality corresponding to neomycin B.Deblocking and reduction of the azido groups then gave neomycin B.