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02:30Chirality at Nitrogen, Phosphorus, and Sulfur
Chirality is most prevalent in carbon-based tetrahedral compounds, but this important facet of molecular symmetry extends to sp3-hybridized nitrogen, phosphorus and sulfur centers, including trivalent molecules with lone pairs. Here, the lone pair behaves as a functional group in addition to the other three substituents to form an analogous tetrahedral center that can be chiral.
A consequence of chirality is the need for enantiomeric resolution. While this is theoretically possible for all...
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02:05Prochirality
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Chirality is the most intriguing yet essential facet of nature, governing life’s biochemical processes and precision. It can be observed from a snail shell pattern in a macroscopic world to an amino acid, the minutest building block of life. Most of the snails around the world have right-coiled shells because of the intrinsic chirality in their genes. All the amino acids present in the human body exist in an enantiomerically pure state, except for glycine - the sole achiral amino acid. The...
02:34Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
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01:26Photochemical Electrocyclic Reactions: Stereochemistry
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Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
01:33Radical Halogenation: Stereochemistry
Stereochemistry is the study of the different spatial arrangements of atoms in a given molecule. The stereochemistry of radical halogenations can be understood from three different situations:
Halogenation to form a new chiral center:
Halogenation to form a new chiral center:
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Related Experiment Video
Updated: Jul 28, 2026
08:26
Synthesis of Zeolites Using the ADOR (Assembly-Disassembly-Organization-Reassembly) Route
Published on: April 3, 2016
Chiral photochemistry within zeolites
1Department of Chemistry, Tulane University, New Orleans, LA 70118, USA.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|June 7, 2000
Summary
Zeolites enable efficient chiral induction in photochemical reactions by confining reactants and chiral inducers. This method overcomes limitations of solution-phase photoreactions, achieving high enantiomeric enrichment.
Area of Science:
- Photochemistry
- Organic Synthesis
- Materials Science
Background:
- Chiral induction in thermal reactions is well-understood, but challenging in photochemical reactions due to short excited state lifetimes.
- Photochemical chiral induction in solution is often inefficient, while solid-state methods have limitations.
- Zeolites offer a potential medium for enhancing photochemical chiral induction, addressing limitations of crystallization-dependent solid-state approaches.
Purpose of the Study:
- To explore the use of zeolites as a medium for achieving efficient chiral induction in photochemical reactions.
- To investigate the role of zeolite confinement in promoting intimate interactions between reactants and chiral inducers.
- To compare the efficacy of zeolite-mediated photoreactions with traditional solution-phase methods.
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Main Methods:
- Utilizing chirally modified zeolites as reaction media for photochemical transformations.
- Investigating the photoelectrocylization of tropolone alkyl ethers as a model reaction.
- Comparing enantiomeric enrichment achieved in zeolite supercages versus isotropic solvent media.
Main Results:
- Chiral induction in solution-phase photoreactions yielded negligible results.
- Photoreactions conducted within zeolite supercages demonstrated significant chiral induction, reaching up to 90%.
- The confined environment of zeolites facilitated intimate reactant-chiral inducer interactions, leading to enantiomerically enriched products.
Conclusions:
- Zeolites provide an effective microenvironment for enhancing photochemical chiral induction.
- The confinement effect in zeolites promotes specific interactions crucial for asymmetric synthesis.
- Chirally modified zeolites represent a promising strategy for efficient enantioselective photoreactions.