The stepwise degradation of a glycosylated aldose. A potential method for sequencing branched oligosaccharides

2,3,6,2',3',4',6'-Hepta-O-methylmaltose diethyl dithioacetal (2), obtained under mild conditions from N-methyl-hepta-O-methyl-N-p-nitrophenyl-beta-maltosylamine (1), was converted into the disulfone 4. Storage of a solution of 4 in aqueous tetrahydrofuran gave 1,2-dideoxy-1,1-bis(ethylsulfonyl)hepta-O-methylmalt-1-en itol (5). Fragmentation of 5 with aqueous ammonia released 2,3,4,6-tetra-O-methyl-D-glucose. The degradation procedure has potential for the sequencing of branched oligosaccharides.