Synthesis of methyl alpha-D-glucopyranosyl-(1-->4)-alpha-D-galactopyranoside and methyl alpha-D-xylo-hex-4-ulopyranosyl-(1-->4)-alpha-D-galactopyranoside.
The syntheses of methyl alpha-D-glucopyranosyl-(1-->4)-alpha-D-galactopyranoside (1) and methyl alpha-D-xylo-hex-4-ulopyranosyl-(1-->4)-alpha-D-galactopyranoside (4) are reported. The keto-disaccharide 4 is of interest in our design, synthesis, and study of pectate lyase inhibitors. The key step in the syntheses was the high-yielding, stereospecific formation of methyl 4,6-O-benzylidene-2',3'-di-O-benzyl-alpha-D-glucopyranosyl-(1-->4)-2,3,6-tri-O-benzyl-alpha-D-galactopyranoside (15), which was accomplished by reacting 2,3-di-O-benzyl-4,6-O-benzylidene-D-glucopyranosyl trichloroacetimidate (10) with methyl 2,3,6-tri-O-benzyl-alpha-D-galactopyranoside (14) in the presence of a catalytic amount of tert-butyldimethylsilyl trifluoromethane sulfonate (TMSOTF). Compound 15 was either hydrogenolyzed to yield disaccharide 1 or treated with NaBH3CN-HCl in 1:1 tetrahydrofuran-ether to yield methyl 2,3,6-tri-O-benzyl-alpha-D-glucopyranosyl-(1-->4)-2,3,6-tri-O-benzyl-alpha-D-galactopyranoside (2). The free 4'-OH of compound 2 was oxidized to a carbonyl group by a Swern oxidation, and the protecting groups were removed by hydrogenolysis to yield keto-disaccharide 4. These synthetic pathways were simple, yet high yielding.
Liotta
L J
LJ
Department of Chemistry, Stonehill College, Easton, MA 02357, USA. lliotta@stonehill.edu
Capotosto
R D
RD
Garbitt
R A
RA
Horan
B M
BM
Kelly
P J
PJ
Koleros
A P
AP
Brouillette
L M
LM
Kuhn
A M
AM
Targontsidis
S
S
D004187:Disaccharides / Q000138:chemical synthesis*; D015195:Drug Design; D004791:Enzyme Inhibitors / Q000138:chemical synthesis; D011133:Polysaccharide-Lyases / Q000037:antagonists & inhibitors; D013237:Stereoisomerism
D004187:Disaccharides; D004791:Enzyme Inhibitors; C443799:methyl-glucopyranosyl-(1-4)-galactopyranoside; C443801:methyl-xylo-hex-4-ulopyranosyl-(1-4)-galactopyranoside; D011133:Polysaccharide-Lyases; C023911:pectate lyase