1201012-02-3Relevant academic research and scientific papers
Neighboring group participation in glycosylation reactions by 2,6-disubstituted 2-O-benzoyl groups: A mechanistic investigation
Williams, Rohan J.,McGill, Nathan W.,White, Jonathan M.,Williams, Spencer J.
, p. 236 - 263 (2011/04/22)
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-trimethylbenzoyl)-1-thio-β-D- galactopyranoside afforded only dioxolenium ion, whereas 4-methylphenyl 3,4,6-tri-O-acetyl-2-O-(2,4,6-trimethylbenzoyl)-1-thio-β-D- galactopyranoside gave a 1:1 mixture of dioxolenium ion and glycosyl triflate. However, the reaction intermediates formed from these deactivated donors do not influence the glycosylation stereoselectivity; instead, it is influenced by steric and electronic interactions at the transition states. Copyright Taylor & Francis Group, LLC.
2,6-Disubstituted benzoates as neighboring groups for enhanced diastereoselectivity in β-galactosylation reactions: Synthesis of β-1,3-linked oligogalactosides related to arabinogalactan proteins
McGill, Nathan W.,Williams, Spencer J.
scheme or table, p. 9388 - 9398 (2010/03/04)
(Chemical Equation Presented) Arabinogalactan proteins (AGPs) are plant glycoproteins which contain a β-1,3-linked galactan core. The synthesis of the β-galactopyranose-1,3-β-galactopyranose linkage using various 2-O-acyl-protected glycosyl donors has bee
