Organic synthetic methods
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
---The tetrasaccharide 5-aminopentyl glycoside β-D-Manp-(1→4)-β-D-Glcp-(1→4)-α-L-Rhap-(1→3)-β-D-Glcp-1-O-(CH2)5NH2(22) related to the exopolysaccharide of Arthrobacter sp. CE-17 was synthesized by coupling of the properly protected disaccharide blocks β-D-Manp-(1→4)-β-D-Glcp-1-S-Ph (11) and α-L-Rhap-(1→3)-β-D-Glcp-1-O-(CH2)5NHZ (20). Building block 11 was obtained by intramolecular β-mannosylation of a malonyl-tethered disaccharide glycoside which was prepared from phenyl 4,6-O-benzylidene-1-thio-β-D-glucopyranoside (1) and ethyl 2,3,4-tri-O-benzyl-1-thio-α-D-mannopyranoside (5) in 5 steps. Building block 20 was obtained by coupling N-Z-protected 5-aminopentyl 2-O-benzyl-4,6-O-benzylidene-β-D-glucopyranoside (14) obtained from the non-benzylated counterpart 12 with ethyl 2,3-di-O-benzoyl-4-O-chloroacetyl-1-thio-α-L-rhamnopyranoside (18) obtained in 3 steps from ethyl 2,3-O-isopropylidene-1-thio-α-L-rhamnopyranoside (15).
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