Acid-Base Catalysis Concept in Glycosidation

Adduct formation between glycosyl acceptors (alcohols, thiols) and arylboron fluorides or arylsilicon fluorides, respectively, as catalyst permits acid-base-catalyzed glycoside bond formation with O-glycosyl trichloroacetimidates as glycosyl donors. Thus, from various glycosyl donors and acceptors, 1,2-trans glycosides could be obtained with very high yield and anomeric selectivity. This way, also 1,2-cis glycosides were accessible with reactive, sterically not-demanding glycosyl acceptors. By the results an intramolecular nucleophilic substitution (S_N2-type) reaction course is supported that leads to concomitant donor and acceptor activation by the catalyst. Similarly, in the activation of O-glycosyl trichloroacetimidates by Brønsted acids as catalyst, the bis-N,N′-[3,5-bis-(trifluoromethyl)phenyl]-thiourea (8) as cocatalyst exhibits a cooperative behavior. This compound enables hydrogen-bond-mediated complex formation between the donor, the acceptor, and the acid catalyst. This way, an acid-base-catalyzed S_N2-type glycoside bond formation is facilitated even at room temperature and in the absence of anchimeric assistance. Thus, a strong influence of 8 on reaction rate, yield, and anomeric selectivity is exerted.

Authors and Affiliations

1. Department of Chemistry, Indian Institute of Technology, Patna, India

   Amit Kumar

2. Universität Konstanz, Fachbereich Chemie, Fach 725, D-78457, Konstanz, Germany

   Richard R. Schmidt

3. Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah, 21589, Saudi Arabia

   Richard R. Schmidt

Corresponding author

Correspondence to Richard R. Schmidt .

Editors and Affiliations

1. Tokyo Metropolitan Institute of Gerontology, Tokyo Metropolitan Geriatric Hospital, Tokyo, Japan

   Tamao Endo

2. Department of Biomolecular Systems, Max-Planck-Institute of Colloids and Interfaces, Potsdam, Germany

   Peter H. Seeberger

3. Dept. Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA

   Gerald W. Hart

4. Academia Sinica, Nankang, Taipei, Taiwan

   Chi-Huey Wong

5. Systems Glycobiology Group, RIKEN-Max Planck Joint Research Center for Systems Chemical Biology, Wako, Saitama, Japan

   Naoyuki Taniguchi

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