556
3
Chemical Glycosylation Reactions
5 Intramolecular Glycosylation Through 1-O-Acyl Linkages
Ishido and coworkers reported a new method for the synthesis of O-glycosides by the pyrolysis
of 1-O-aryloxycarbonyl sugar derivatives: for example, the pyrolysis of 2,3,4,6-tetra-O-acetyl1-O-phenoxycarbonyl-β-D-glucopyranose at 170 o C afforded phenyl 2,3,4,6-tetra-O-acetylβ-D-glycopyranoside in moderate yield ( > Scheme 71) [82,83]. Ikegami [84] and Schmidt [85]
et al. developed a novel intramolecular decarboxylative glycosylation via mixed carbonate as
a two-step glycosylation procedure, which involves linking two sugars by using the carbonate as a connector and subsequent extrusion of carbon dioxide to form a glycosyl bond by
the aid of Lewis acid, TMSOTf or TBSOTf ( > Scheme 72). Ikegami et al. also reported that
⊡ Scheme 72
(Ref. [84,85])
⊡ Scheme 73
(Ref. [86,87,88])
3
Chemical Glycosylation Reactions
5 Intramolecular Glycosylation Through 1-O-Acyl Linkages
Ishido and coworkers reported a new method for the synthesis of O-glycosides by the pyrolysis
of 1-O-aryloxycarbonyl sugar derivatives: for example, the pyrolysis of 2,3,4,6-tetra-O-acetyl1-O-phenoxycarbonyl-β-D-glucopyranose at 170 o C afforded phenyl 2,3,4,6-tetra-O-acetylβ-D-glycopyranoside in moderate yield ( > Scheme 71) [82,83]. Ikegami [84] and Schmidt [85]
et al. developed a novel intramolecular decarboxylative glycosylation via mixed carbonate as
a two-step glycosylation procedure, which involves linking two sugars by using the carbonate as a connector and subsequent extrusion of carbon dioxide to form a glycosyl bond by
the aid of Lewis acid, TMSOTf or TBSOTf ( > Scheme 72). Ikegami et al. also reported that
⊡ Scheme 72
(Ref. [84,85])
⊡ Scheme 73
(Ref. [86,87,88])