Solvent-Dependent Mechanism and Stereochemistry of Mitsunobu Glycosylation with Unprotected Pyranoses

• DOI: 10.1021/acs.orglett.0c01549
• Publication Date: 2020-06-04T17:24:22Z
• Authors: Hironori Takeuchi; Yusuke Fujimori; Yoshihiro Ueda; Hiromitsu Shibayama; Masaru Nagaishi; Tomoyuki Yoshimura; Takahiro Sasamori; Norihiro Tokitoh; Takumi Furuta; Takeo Kawabata
• Keywords: SN2 reaction; Mitsunobu reaction; Boronic acid

An SN2 mechanism was proposed for highly stereoselective glycosylation of benzoic acid with unprotected α-d-glucose under Mitsunobu conditions in dioxane, while an SN1 indicated nonstereoselective DMF. The SN2-type is generally applicable to various pyranoses as glycosyl donors combination a wide range acidic acceptors such carboxylic acids, phenols, and imides, retaining its high stereoselectivity (33 examples). Glycosylation α-d-mannose proceeded also manner directly afford usually less accessible 1,2-cis-mannoside. One- or two-step total syntheses five simple natural glycosides were performed using the strategy presented here α-d-glucose.