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Exploitation of sugar ring flipping for a hinge-type tether assisting a [2 + 2] cycloaddition
Hideya Yuasa1, Masatoshi Nakatani, Hironobu Hashimoto
1Department of Life Science, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 J2-10, Midoriku, Yokohama 226-8501, Japan. hyuasa@bio.titech.ac.jp
Organic & Biomolecular Chemistry
|September 23, 2006
Summary
Researchers developed a novel hinge-type tether using Methyl 3-O-p-methoxybenzyl-beta-D-xylopyranoside for [2 + 2] cycloaddition reactions. This method achieved excellent beta-selectivity in intramolecular cinnamate cycloadditions, yielding truxinates.
Area of Science:
- Organic Chemistry
- Photochemistry
- Carbohydrate Chemistry
Background:
- Exploration of novel tethering strategies for [2 + 2] cycloaddition reactions.
- Investigation of conformational preferences in carbohydrate derivatives.
- Understanding the influence of conformation on photochemical reactivity.
Purpose of the Study:
- To utilize Methyl 3-O-p-methoxybenzyl-beta-D-xylopyranoside as a hinge-type tether for cinnamate [2 + 2] cycloadditions.
- To analyze the conformational dynamics and their impact on the stereochemical outcome of intramolecular cycloadditions.
- To achieve high regio- and stereoselectivity in the synthesis of truxinate derivatives.
Main Methods:
- Synthesis of a novel hinge-type tether based on Methyl 3-O-p-methoxybenzyl-beta-D-xylopyranoside.
- Photochemical [2 + 2] cycloaddition of cinnamate derivatives under UV irradiation (313 nm).
- Conformational analysis using 1H NMR spectroscopy on per-deuterated derivatives.
- Transesterification to yield final truxinate products.
Main Results:
- The 2,4-dicinnamate derivative adopted a 4C1 conformation, while the 3-O-deprotected version favored a 1C4 conformation in non-polar solvents.
- Photoirradiation of the dicinnamate derivative yielded methyl beta-, delta-, and xi-truxinates in an 86:8:6 ratio.
- Conformational analysis confirmed fixed 1C4 pyranoside rings in all photoirradiation products.
- Excellent beta-selectivity was observed with m-bromocinnamate under hinge-tethered conditions.
Conclusions:
- The hinge-type tether strategy effectively controls the conformation and reactivity of cinnamates for [2 + 2] cycloaddition.
- The 1C4 conformation is crucial for facilitating intramolecular cycloaddition with high stereoselectivity.
- This approach offers a versatile route to synthesize complex truxinate structures with excellent beta-selectivity.
![Solid-phase Synthesis of [4.4] Spirocyclic Oximes](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F58508.jpg&w=3840&q=50)
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