Related Concept Videos
02:57Sharpless Epoxidation
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The conversion of allylic alcohols into epoxides using the chiral catalyst was discovered by K. Barry Sharpless and is known as Sharpless epoxidation. The use of a chiral catalyst enables the formation of one enantiomer of the product in excess. This chiral catalyst is mainly a chiral complex of titanium tetraisopropoxide and tartrate ester (specific stereoisomer). The stereoisomer used in the chiral catalyst dictates the formation of the enantiomer of the product. In other words, the use of...
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01:17Thermal Electrocyclic Reactions: Stereochemistry
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The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
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01:26Photochemical Electrocyclic Reactions: Stereochemistry
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The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
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01:12Stereochemical Effects of Enolization
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The chiral α-carbon of the carbonyl compound is the stereocenter of the molecule. As shown in the figure below, when such a carbonyl compound undergoes racemization under an acidic or basic condition, an achiral enol is formed.
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01:26Thermal and Photochemical Electrocyclic Reactions: Overview
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Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
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02:24Properties of Enantiomers and Optical Activity
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It is essential to understand the difference between chiral and achiral interactions and the implications thereof in optical activity and their applications. Just as our feet, which are chiral, interact uniquely with chiral objects, such as a pair of shoes, but identically with achiral socks, enantiomers of a molecule exhibit different properties only when they interact with other chiral media. An example of a significant implication from this facet is the phenomenon known as optical activity,...
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Pulsed electroconversion for highly selective enantiomer synthesis.
Chularat Wattanakit1, Thittaya Yutthalekha2, Sunpet Asssavapanumat2,3
1Department of Chemical and Biomolecular Engineering, School of Energy Science and Engineering, Vidyasirimedhi Institute of Science and Technology, Rayong, 21210, Thailand. chularat.w@vistec.ac.th.
Nature Communications
|December 14, 2017
Summary
Researchers developed a new method for asymmetric synthesis using pulsed electrochemical conversion. This approach achieves over 90% enantiomeric excess for chiral compounds, offering a promising route for pharmaceutical development.
Area of Science:
- Chemistry
- Materials Science
- Electrochemistry
Background:
- Asymmetric synthesis is vital for producing pure chiral compounds used in medicine, biotechnology, and chemistry.
- Existing methods for increasing enantiomeric yield have limitations, necessitating novel, highly enantioselective reaction concepts.
- The pharmaceutical industry shows an increasing demand for enantiopure products, driving innovation in synthetic strategies.
Purpose of the Study:
- To introduce a novel strategy for the asymmetric synthesis of chiral compounds.
- To demonstrate the efficacy of pulsed electrochemical conversion for enantioselective synthesis.
- To explore the potential of chiral mesoporous metal structures in electrocatalysis.
Main Methods:
- Utilized pulsed electrochemical conversion for molecular synthesis.
- Employed chiral mesoporous metal structures as catalytic platforms.
- Investigated the stereospecific electroreduction of a prochiral model molecule.
Main Results:
- Achieved an enantiomeric excess of over 90% in the synthesized chiral compounds.
- Demonstrated the feasibility of the pulsed electrochemical approach for asymmetric synthesis.
- Confirmed the stereospecificity of the electroreduction process.
Conclusions:
- Pulsed electrochemical conversion offers a promising new paradigm for enantioselective synthesis.
- Chiral mesoporous metal structures are effective catalysts for achieving high enantiomeric excess.
- This method provides a straightforward route for synthesizing high-added-value chiral molecules.