Stereoselectivity
Stereoselectivity - Related Videos
06:31
Highly Stereoselective Synthesis of 1,6-Ketoesters Mediated by Ionic Liquids: A Three-component Reaction Enabling Rapid Access to a New Class of Low Molecular Weight Gelators
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Cited by 4 •
2015
Ionic liquids (ILs) mediate fast, simple and cheap access to 1,6-ketoesters in high diastereoselectivities and good yields. The reaction protocol is robust and the 1,6-ketoesters can be obtained in gram scale after a simple filtration protocol. Moreover, the 1,6-ketoesters are potent gelators in hydrocarbon solvents.
06:31
Organocatalysis
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2023
Source: Vy M. Dong and Faben Cruz, Department of Chemistry, University of California, Irvine, CA This experiment will demonstrate the concept of organocatalysis by illustrating the proper setup of a reaction that utilizes enamine catalysis. Organocatalysis is a form of catalysis that uses substoichiometric amounts of small organic molecules to accelerate reactions. This type of catalysis is complementary to other forms of catalysis such as transition metal or biocatalysis. Transition metal...
06:52
Ozonolysis of Alkenes
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2023
Source: Vy M. Dong and Zhiwei Chen, Department of Chemistry, University of California, Irvine, CA This experiment will demonstrate an example of an ozonolysis reaction to synthesize vanillin from isoeugenol (Figure 1). Ozonolysis of alkenes, an oxidation reaction between ozone and an alkene, is a common method to prepare aldehydes, ketones, and carboxylic acids. This experiment also demonstrates the use of an ozone generator and a low temperature (−78 °C) reaction. Figure 1. Diagram showing...
11:08
Chemo-enzymatic Synthesis of N-glycans for Array Development and HIV Antibody Profiling
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Cited by 2 •
2018
A modular approach to the synthesis of N-glycans for attachment to an aluminum oxide-coated glass slide (ACG slide) as a glycan microarray has been developed and its use for the profiling of an HIV broadly neutralizing antibody has been demonstrated.
09:42
Solid Phase Synthesis
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2023
Source: Vy M. Dong and Diane Le, Department of Chemistry, University of California, Irvine, CA Merrifield's solid-phase synthesis is a Nobel Prize winning invention where a reactant molecule is bound on a solid support and undergoes successive chemical reactions to form a desired compound. When the molecules are bound to a solid support, excess reagents and byproducts can be removed by washing away the impurities, while the target compound remains bound to the resin. Specifically, we will...
FAQs
Stereoselectivity reflects differences in the energy required to reach alternative transition states, the temporary arrangements of atoms formed during a reaction. A pathway with more favorable spatial interactions or electronic effects is reached more readily, so its stereoisomeric product forms in a larger amount. Comparing these pathways helps chemists predict which three-dimensional arrangement will dominate.
Spatial interactions determine how comfortably reactants and developing bonds can be arranged as a reaction proceeds. When one transition-state arrangement is more favorable than another, the corresponding pathway becomes easier to access. This principle explains why the same reacting components can produce unequal amounts of stereoisomers and why molecular geometry must be considered during reaction design.
Electronic effects can change the relative favorability of competing transition states, alongside the spatial relationships among atoms. These effects help determine which pathway proceeds more readily and therefore which configuration or geometric arrangement appears in greater proportion. Considering both electronic and spatial factors gives a more complete basis for predicting stereochemical outcomes in chemistry.
A stereoselective reaction may favor one enantiomer, a stereoisomer related as a distinct mirror-image form, or one diastereomer, a stereoisomer with a different three-dimensional relationship that is not that mirror image. In either case, the products are formed in unequal amounts. Identifying the product relationship clarifies what kind of stereochemical control the reaction achieves.
Chemists can use stereoselectivity to plan reactions that favor a desired configuration or geometric arrangement in newly formed bonds. They assess how the reactants, catalyst, and reaction conditions may influence competing energy pathways, then select an approach expected to produce the preferred stereoisomer. This strategy can make syntheses more efficient by reducing formation of less useful alternatives.
The relative amounts of stereoisomeric products reveal how strongly the reaction favors one three-dimensional outcome over others. Examining whether the products are enantiomers or diastereomers also identifies the type of stereochemical relationship involved. Such results help chemists evaluate reaction control and connect molecular arrangement with properties relevant to chemical and biological function.
Stereoselectivity helps chemists control the three-dimensional structures produced during pharmaceutical and natural-product syntheses. Because molecular structure influences biological activity, favoring one stereoisomer can be important when preparing compounds with the intended function. The principle therefore connects reaction design with the efficient preparation of biologically relevant molecules and with understanding how their structures affect activity.