Highly beta-selective O-glucosidation due to the restricted twist-boat conformation.
[reaction: see text] Ethyl 1-thio-2,3,4,6-tetrakis-O-triisopropylsilyl-beta-d-glucopyranoside, ethyl 6-O-benzyl-1-thio-2,3,4-tris-O-triisopropylsilyl-beta-d-glucopyranoside, and ethyl 6-O-pivaloyl-1-thio-2,3,4-tris-O-triisopropylsilyl-beta-d-glucopyranoside induced highly beta-selective O-glucosidations. Among them, the 6-O-pivaloylated substrate provided the best selectivity up to alpha/beta = 3:97 with cyclohexylmethanol, and the substrate was used for glucosidations with secondary and tertiary alcohols in a highly beta-selective manner. The selectivity would be caused by the twist-boat conformation of the pyranose; this is the first beta-selective O-glucosidation based on conformational control of the pyranose ring.
Okada
Yasunori
Y
School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda 669-1337, Japan.
Mukae
Tatsuya
T
Okajima
Kotaro
K
Taira
Miyoko
M
Fujita
Mari
M
Yamada
Hidetoshi
H
D003510:Cyclohexanes / Q000737:chemistry; D005030:Ethylenes / Q000737:chemistry; D006027:Glycosides / Q000737:chemistry*; D008968:Molecular Conformation; D013438:Sulfhydryl Compounds / Q000737:chemistry
D003510:Cyclohexanes; D005030:Ethylenes; D006027:Glycosides; D013438:Sulfhydryl Compounds; C004707:cyclohexylmethanol; C036216:ethylene