Highly beta-selective and direct formation of 2-O-glycosylated glucosides by ring restriction into twist-boat.
Three disaccharide donors, ethyl 2-O-(2,3,4-tris-O-tert-butyldimethylsilyl-beta-D-xylopyranosyl)-3,4,6-tris-O-tert-butyldimethylsilyl-1-thio-beta-D-glucopyranoside, ethyl 2-O-(2,3,4-tris-O-tert-butyldimethylsilyl-alpha-L-rhamnopyranosyl)-3,4,6-tris-O-tert-butyldimethylsilyl-1-thio-beta-D-glucopyranoside, and ethyl 2-O-(2,3,4,6-tetrakis-O-tert-butyldimethylsilyl-beta-D-glucopyranosyl)-3,4,6-tris-O-tert-butyldimethylsilyl-1-thio-beta-D-glucopyranoside, produced a highly beta-selective glycosidation up to alpha/beta = 2/98 using MeOTf as the activator and 2,6-lutidine as an additive. The ring conformations of the glucose part in these disaccharide donors were all restricted to 3S1, and the conformation would lead to the stereoselectivity.
Okada
Yasunori
Y
School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda 669-1337, Japan.
Nagata
Osamu
O
Taira
Miyoko
M
Yamada
Hidetoshi
H
D002236:Carbohydrate Conformation; D005960:Glucosides / Q000737:chemistry*; D006031:Glycosylation
D005960:Glucosides