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Volume 81, Issue 9 ( September, 1, 2010 ), Pages 2105-2121
Received, 25th June, 2010, Accepted, 15th July, 2010, Published online, 15th July, 2010. |
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| A Novel Pentose Synthesis via Palladium(II)-Catalyzed Cyclization of an Unstable Hemiacetal |
Ken-ichiro Awasaguchi, Masahiro Miyazawa,* Ikuyo Uoya, Koichi Inoue, Koji Nakamura, Hajime Yokoyama, and Yoshiro Hirai*
Department of Chemistry, Graduate School of Science and Engineering, Toyama University, Gofuku 3190, Toyama 930-8555, Japan |
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Abstract
PdCl2(PhCN)2 (5 mol%)-catalyzed cyclization of a hemiacetal derived from (E,2S,3R)-2,3-isopropylidenedioxy-6-(tetrahydro-2H-pyran-2-yl)-4-hexenal and methanol gave substituted furanoside in moderate yield, exclusively via 5-exo-mode cyclization, without the need for a reoxidant. New stereogenic centers at C1 and C4 on the tetrahydrofuran ring showed preferential 1R and 4R stereochemistry due to anomeric effect (no-σ*c-o) and A1,2 strain, respectively. This methodology was applied to stereocontrolled synthesis of pentoses: D-ribose and L-lyxose. |
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Graphical Abstract
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Keywords
1. Palladium Catalyst
2. Hemiacetal
3. Tetrahydrofuran
4. Cyclization
5. Pentose
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| Corresponding author; email: miyazawa@sci.u-toyama.ac.jp |
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