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Synlett 1998; 1998(10): 1102-1104
DOI: 10.1055/s-1998-1894
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Highly Optimized β-Mannosylation via p-Methoxybenzyl Assisted Intramolecular Aglycon Delivery

Yukishige Ito* , Yuki Ohnishi, Tomoya Ogawa, Yoshiaki Nakahara
  • *The Institute of Physical and Chemical Research (RIKEN) and CREST, Japan Science and Technology Corporation (JST), 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan; Fax + 81-48-462-4680; E-mail: yukito@postman.riken.go.jp
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Publikationsdatum:
31. Dezember 2000 (online)

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Highly efficient and stereoselective β-mannosylation was achieved by using mannosyl thioglycosides 5 and 19. Intramolecular aglycon delivery (IAD) from mixed acetal 12, 15 and 20, obtainable by oxidative coupling of aglycon onto mannosyl thio-glycosides which carry p-methoxybenzyl (PMB) group at C-2 position, was performed by the action of MeOSO2CF3 to afford β-mannosides 13/16/21. It is to be noted that efficiency of IAD was substantially improved by changing the protecting group at the 4- and 6-positions from previously utilized benzylidene to cyclohexylidene (5) or TIPDS (19) group. As a result, it is now possible to perform the β-manno glycosylation in a highly optimized manner to afford di- and trisaccharides with a backbone structure corresponding to asparagine-linked oligosaccharides in 75-85% yield as single stereoisomers.

β-mannosylation - intramolecular aglycon delivery - thioglycoside - asparagine-linked oligosaccharide