Takashi Yamanoi

The catalytic synthesis of aryl O-glycosides using triaryloxyboranes

Triaryloxyboranes worked as highly reactive glycosyl acceptors of glycosyl acetates to afford aryl O-glycosides in excellent yields. A catalytic amount of ytterbium(III) trifluoromethanesulfonate activated the formation reaction of aryl O-glycosidic linkages between the glycosyl acetates and triaryloxyboranes.

Synthesis, structure, and evaluation of a β-cyclodextrin-artificial carbohydrate conjugate for use as a doxorubicin-carrying molecule.

This paper describes the synthesis of a β-cyclodextrin (β-CyD) derivative conjugated with a C,C-glucopyranoside containing a benzene unit. Its doxorubicin-inclusion ability and structure are also discussed. SPR analysis revealed that the β-CyD conjugate had a high inclusion association value of 3.8×10(6)M(-1) for immobilized doxorubicin. NMR structural analysis suggested that its high doxorubicin-inclusion ability was due to the formation of the inclusion complex as a result of the π-π stacking interaction between the benzene ring of the conjugate and the A ring of doxorubicin.

Stereoselectivity of D-Psicofuranosylation Influenced by Protecting Groups of Psicofuranosyl Donors

Abstract – We synthesized several types of novel D-psicofuranosyl acetate derivatives, and investigated their use as glycosyl donors in scandium triflate-catalyzed D-psicofuranosylation reactions. Psicofuranosylation demonstrated unique stereoselectivities depending on the protecting groups of psicofuranosyl donors. The donor having a 3,4-isopropylidene group afforded β-psicofuranosides with high stereoselectivities. Donors having a C3 benzoyloxy group demonstrated low stereoselectivities with no neighboring group participation. This study also discusses the stereoselectivities of psicofuranosylation based on the conformers of the glycosyl oxocarbenium ion intermediates as influenced by the protecting groups of the psicofuranosyl donors. We also compared the neighboring group participation of the glycosyl donors bearing a C3 benzoyloxy group during D-psicofuranosylation and D-fructofuranosylation.

Complete NMR assignment of a bisecting hybrid-type oligosaccharide transferred by Mucor hiemalis endo-β-N-acetylglucosaminidase

This study describes the complete nuclear magnetic resonance (NMR) spectral assignment of a bisecting hybrid-type oligosaccharide 1, transferred by Mucor hiemalis endo-β-N-acetylglucosaminidase (Endo-M). Through (1)H- and (13)C-NMR, DQF-COSY, HSQC, HMBC, TOCSY, and NOESY experiments, we determine the structure of the glycoside linkage formed by the Endo-M transglycosylation, i.e., the connection between GlcNAc and GlcNAc in oligosaccharide 1.