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Unique Reactivity of the Mukaiyama Glycosidation Catalyst (SnCl 3 ClO 4 ) Toward β‐Mannopyranosides
Author(s) -
Wang Yonghui,
Cheon HwanSung,
Kishi Yoshito
Publication year - 2008
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.200700297
Subject(s) - anomer , chemistry , stereoselectivity , reactivity (psychology) , moiety , selectivity , catalysis , beta (programming language) , substrate (aquarium) , stereochemistry , alpha (finance) , organic chemistry , programming language , medicine , construct validity , oceanography , alternative medicine , nursing , pathology , computer science , patient satisfaction , geology
Abstract Glycosidation of a mannosyl donor in the presence of the Mukaiyama catalyst was found to give exceptionally high α/β selectivity. A systematic study was conducted to reveal that selective β‐to‐α anomerization accounts for the observed high α/β stereoselectivity. Furthermore, the Mukaiyama catalyst was shown to exhibit an unusual level of substrate and anomer selectivity for the anomerization. On the basis of the combined anomeric and Δ2 effects, a mechanistic rationale was proposed, thereby suggesting the minimum structural moiety essential for the anomerization in question. With this analysis, β‐talo‐, β‐altro‐, and β‐idopyranosides are predicted to exhibit a reactivity profile similar to β‐mannopyranosides, but all other pyranosides should not. This prediction was verified by using β‐ and α‐talopyranosides as an example.