A novel method for stereoselective glycosidation with thioglycosides: Promotion by hypervalent iodine reagents prepared from PhIO and various acids.
作者:Koichi Fukase、Ikuko Kinoshita、Takeshi Kanoh、Yoshihiko Nakai、Atsushi Hasuoka、Shoichi Kusumoto
DOI:10.1016/s0040-4020(96)00057-9
日期:1996.3
Combinations of iodosobenzene (PhIO) and various acids effectively promote glycosidation using thioglycosides as glycosyl donors. beta-Selective glucosidation was effected by use of TfOH, Tf(2)O, TMSOTf, Sn(OTf)(2), and Yb(OTf)(3) as catalysts with 2-O-benzoylated or 2-O-benzylated donors by virtue of either the neighboring group participation or the solvent effect of acetonitrile, respectively. Combinations of PhIO with SnCl2-AgClO4, SnCl4-AgClO4, BiCl3-AgClO4, and SbCl3-AgClO4 in ether were advantageous for alpha-glucosidation, where 2,2,2-trichloroethoxycarbonyl group introduced at the 6-position of a 2-O-benzylated donor remarkably increased alpha-selectivity.