TY - JOUR
T1 - Boronic-Acid-Catalyzed Regioselective and 1,2- cis -Stereoselective Glycosylation of Unprotected Sugar Acceptors via SNi-Type Mechanism
AU - Tanaka, Masamichi
AU - Nakagawa, Akira
AU - Nishi, Nobuya
AU - Iijima, Kiyoko
AU - Sawa, Ryuichi
AU - Takahashi, Daisuke
AU - Toshima, Kazunobu
N1 - Funding Information:
We wish to thank Dr. Yu Tsutsumi (Principal Scientist of Bruker Biospin K.K.) for helpful support in the quantitative 13C NMR experiments. This research was supported in part by the MEXT-supported Program for the Strategic Research Foundation at Private Universities, 2012-2016 (No. S1201020), JSPS KAKENHI Grant Numbers JP16H01161 in Middle Molecular Strategy and JP16K05781 in Scientific Research (C), a SUNBOR Grant from the Suntory Foundation for Life Sciences, and the Sasagawa Scientific Research Grant from the Japan Science Society.
Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/3/14
Y1 - 2018/3/14
N2 - Regio- and 1,2-cis-stereoselective chemical glycosylation of unprotected glycosyl acceptors has been in great demand for the efficient synthesis of natural glycosides. However, simultaneously regulating these selectivities has been a longstanding problem in synthetic organic chemistry. In nature, glycosyl transferases catalyze regioselective 1,2-cis-glycosylations via the SNi mechanism, yet no useful chemical glycosylations based on this mechanism have been developed. In this paper, we report a highly regio- and 1,2-cis-stereoselective SNi-type glycosylation of 1,2-anhydro donors and unprotected sugar acceptors using p-nitrophenylboronic acid (10e) as a catalyst in the presence of water under mild conditions. Highly controlled regio- and 1,2-cis-stereoselectivities were achieved via the combination of boron-mediated carbohydrate recognition and the SNi-type mechanism. Mechanistic studies using the KIEs and DFT calculations were consistent with a highly dissociative concerted SNi mechanism. This glycosylation method was applied successfully to the direct glycosylation of unprotected natural glycosides and the efficient synthesis of a complex oligosaccharide with minimal protecting groups.
AB - Regio- and 1,2-cis-stereoselective chemical glycosylation of unprotected glycosyl acceptors has been in great demand for the efficient synthesis of natural glycosides. However, simultaneously regulating these selectivities has been a longstanding problem in synthetic organic chemistry. In nature, glycosyl transferases catalyze regioselective 1,2-cis-glycosylations via the SNi mechanism, yet no useful chemical glycosylations based on this mechanism have been developed. In this paper, we report a highly regio- and 1,2-cis-stereoselective SNi-type glycosylation of 1,2-anhydro donors and unprotected sugar acceptors using p-nitrophenylboronic acid (10e) as a catalyst in the presence of water under mild conditions. Highly controlled regio- and 1,2-cis-stereoselectivities were achieved via the combination of boron-mediated carbohydrate recognition and the SNi-type mechanism. Mechanistic studies using the KIEs and DFT calculations were consistent with a highly dissociative concerted SNi mechanism. This glycosylation method was applied successfully to the direct glycosylation of unprotected natural glycosides and the efficient synthesis of a complex oligosaccharide with minimal protecting groups.
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U2 - 10.1021/jacs.7b12108
DO - 10.1021/jacs.7b12108
M3 - Article
C2 - 29457892
AN - SCOPUS:85043762910
VL - 140
SP - 3644
EP - 3651
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 10
ER -