A novel method for stereoselective glycosidation with thioglycosides: Promotion by hypervalent iodine reagents prepared from PhIO and various acids

Article abstract of DOI:10.1016/S0040-4020(96)00057-9

Combinations of iodosobenzene (PhIO) and various acids effectively promoted glycosidation using thioglycosides as glycosyl donors. β-Selective glucosidation was effected by use of TfOH, Tf₂O, 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-AgClO₄, BiCl₃-AgClO₄, and SbCl₃-AgClO₄ in ether were advantageous for α-glucosidation, where 2,2,2-trichloroethoxycarbonyl group introduced at the 6-position of a 2-O-benzylated donor remarkably increased α-sensitivity.