Two approaches to the synthesis of 3-beta-D-glucopyranosyl-D-glucitol.
Glycosidation of 1,2:5,6-di-O-isopropylidene-D-glucose with tetra-O-acetyl-glucosyl bromide in 1:1 benzene-MeNO2 afforded approximately equal amounts of the 3-O-beta-D-glycoside and the rearranged 6-O-beta-D-glycoside, while in MeCN only the latter was formed. When tetra-O-acetyl-beta-thiophenylglucoside was used as donor in CH2Cl2 in the presence of NIS/TfOH as activator, the 6-O-beta-D-glycoside and a 3-O-orthoester were formed in a 1:2 ratio at -20 degrees C, while at 20 degrees C only the former could be isolated. Glycosidation of 1-O-benzoyl-2,4-O-benzylidene-5,6-O-isopropylidene-d-glucitol with tetra-O-acetyl-glucosyl bromide in MeCN in the presence of Hg(CN)2 afforded the corresponding 3-O-alpha- and 3-O-beta-glycopyranoside in a 1:4 ratio in MeCN and 1:5 in 1:1 benzene-MeNO2, respectively. When Hg(CN)2/HgBr2 was used as promoter, the corresponding orthoester was also formed. When tetra-O-acetyl-beta-thiophenylglucoside was used as donor, the 3-O-beta-anomer and the orthoester were obtained predominantly in a 3:2 ratio together with traces of the 3-O-alpha-glycoside. Both beta-glycosides could be smoothly converted into 3-beta-D-glucopyranosyl-D-glucitol.
Kuszmann
János
J
IVAX Drug Research Institute, H-1325 Budapest, PO Box 82, Hungary. janos.kuszmann@idri.hu
Medgyes
Gábor
G
Boros
Sándor
S
D005960:Glucosides / Q000138:chemical synthesis*; D006027:Glycosides / Q000737:chemistry; D006031:Glycosylation; D013012:Sorbitol / Q000031:analogs & derivatives* / Q000138:chemical synthesis*
C498072:3-glucopyranosylglucitol; D005960:Glucosides; D006027:Glycosides; D013012:Sorbitol