A synthesis of 2-O-methyl-L-lyxose, a component of everninomicins B and D

Abstract

Treatment of 1,2-O-isopropylidene-3-O-methyl-5,6-di-O-methylsulphonyl-α-D-allofuranose (4) with sodium benzoate in hot NN-dimethylformamide gave principally 5,6-di-O-benzoyl-1,2-O-isopropylidene-3-O-methyl-β-L-talofuranose (5), together with the corresponding 6-benzoate (6). Debenzoylation of either compound afforded 1,2-O-isopropylidene-3-O-methyl-β-L-talofuranose (7), which liberated 3-O-methyl-L-talose (9) on hydrolysis with acid. Oxidative degradation of this methylhexose with manganese dioxide afforded 2-O-methyl-L-lyxose (10), a sugar which occurs naturally as a component of the antibiotics everninomicins B and D. The reaction of 6-O-benzoyl-1,2-O-isopropylidene-3-O-methyl-5-O-p-tolylsulphonyl-α-D-allofuranose (17) with potassium acetate in hot NN-dimethylformamide gave mainly 5-O-acetyl-6-O-benzoyl-1,2-O-isopropylidene-3-O-methyl-β-L-talofuranose (18), arising from bimolecular displacement of the C-5 tosyloxy-group.