Journal article

Neighboring Group Participation in Glycosylation Reactions by 2,6-Disubstituted 2-O-Benzoyl groups: A Mechanistic Investigation

Rohan J Williams, Nathan W McGill, Jonathan M White, Spencer J Williams

JOURNAL OF CARBOHYDRATE CHEMISTRY | TAYLOR & FRANCIS INC | Published : 2010

Abstract

Variable yields and glycosylation stereoselectivity were obtained for NIS/TfOH-medi- ated reaction of 4-methoxyphenyl 2,4,6-tetra-O-acetyl-β-D- galactopyranoside and thiogalactosides bearing acetyl, benzoyl, 2,6-dimethoxylbenzoyl, 2,4,6-trimethylbenzoyl, or 2,6-dichlorobenzoyl groups at the 2-positions and acetyl at the remainder. X-ray structures of 4-methylphenyl 2,3,4,6-tetra-O-(2,4,6-trimethylbenzoyl)-1-thio-β-D-galactopyr anoside and 4-methylphenyl 3,4-O-isopropylidene-2,6-di-O-(2,4,6-trimethylbenzoyl)-1-thio- β-D-galactopyranoside revealed slightly distorted 4C1 chair conformations. Variable temperature NMR revealed that activation of 4-methylphenyl 2,3,4,6-tetra-O-(2,4,6-trimethylbenz..

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