TY - JOUR
T1 - Stereospecific β-l-Rhamnopyranosylation through an SNi-Type Mechanism by Using Organoboron Reagents
AU - Nishi, Nobuya
AU - Sueoka, Kazuhiro
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 Japan K.K.) and Mr. Daisuke Yoshidome (Schrç-dinger K.K.) for support of the quantitative 13C-NMR experiments and for helpful advices about the DFT calculations, respectively. This research was supported in part by a JSPS KAKENHI Grant Number 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.
Funding Information:
We wish to thank Dr. Yu Tsutsumi (Principal Scientist of Bruker Japan K.K.) and Mr. Daisuke Yoshidome (Schr?dinger K.K.) for support of the quantitative 13C-NMR experiments and for helpful advices about the DFT calculations, respectively. This research was supported in part by a JSPS KAKENHI Grant Number 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 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2018/10/15
Y1 - 2018/10/15
N2 - Stereospecific β-l-rhamnopyranosylations were conducted using a 1,2-anhydro-l-rhamnopyranose donor and mono-ol or diol acceptors in the presence of a glycosyl-acceptor-derived borinic or boronic ester. Reactions proceeded smoothly to provide the corresponding β-l-rhamnopyranosides (β-l-Rhap) with complete stereoselectivity in moderate to high yields without any further additives under mild conditions. Mechanistic studies of the borinic ester mediated glycosylation using 13C kinetic isotope effect (KIE) measurements and DFT calculations were consistent with a concerted SNi mechanism with an exploded transition state. In addition, the present glycosylation method was applied successfully to the synthesis of a trisaccharide, α-l-Rhap-(1,2)-β-l-Rhap-(1,4)-Glcp, derived from Streptococcus pneumoniae serotypes 7B, 7C, and 7D.
AB - Stereospecific β-l-rhamnopyranosylations were conducted using a 1,2-anhydro-l-rhamnopyranose donor and mono-ol or diol acceptors in the presence of a glycosyl-acceptor-derived borinic or boronic ester. Reactions proceeded smoothly to provide the corresponding β-l-rhamnopyranosides (β-l-Rhap) with complete stereoselectivity in moderate to high yields without any further additives under mild conditions. Mechanistic studies of the borinic ester mediated glycosylation using 13C kinetic isotope effect (KIE) measurements and DFT calculations were consistent with a concerted SNi mechanism with an exploded transition state. In addition, the present glycosylation method was applied successfully to the synthesis of a trisaccharide, α-l-Rhap-(1,2)-β-l-Rhap-(1,4)-Glcp, derived from Streptococcus pneumoniae serotypes 7B, 7C, and 7D.
KW - carbohydrates
KW - glycosylation
KW - organoboron reagents
KW - stereoselectivity
KW - β-l-rhamnosylation
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U2 - 10.1002/anie.201808045
DO - 10.1002/anie.201808045
M3 - Article
C2 - 30098095
AN - SCOPUS:85053662599
VL - 57
SP - 13858
EP - 13862
JO - Angewandte Chemie - International Edition
JF - Angewandte Chemie - International Edition
SN - 1433-7851
IS - 42
ER -