What is stereoselectivity in organic chemistry?
Illustrated Glossary of Organic Chemistry – Stereoselective. Stereoselective: A reaction in which only one stereoisomer among a mixture of stereoisomers reacts. Also a reaction that can in principle produce two or more stereoisomers but in fact produces one (or almost only one) stereoisomer product.
What is regioselectivity vs stereoselectivity?
The key difference between regioselectivity and stereoselectivity is that regioselectivity refers to the formation of one positional isomer over another, whereas stereoselectivity refers to the formation of one stereoisomer over another.
What does it mean if something is stereospecific?
Stereospecific: A reaction in which the stereochemistry of the reactants controls the outcome of the reaction. In general, one stereoisomer of certain reactant produces one stereoisomer of a certain product, whereas a different stereoisomer of the same reactant produces a different stereoisomer of the same product.
What is stereoselectivity in pharmacology?
Stereoselective metabolism of drugs is most commonly the major contributing factor to stereoselectivity in pharmacokinetics. Metabolizing enzymes often display a preference for one enantiomer of a chiral drug over the other, resulting in enantioselectivity.
What causes stereoselectivity?
A stereoselective process is one in which one stereoisomer predominates over another when two or more may be formed. If the products are enantiomers, the reaction is enantioselective; if they are diastereoisomers, the reaction is diastereoselective.
Why is stereoselectivity important?
Stereoselectivity in drug metabolism can not only influence the pharmacological activities, tolerability, safety, and bioavailability of drugs directly, but also cause different kinds of drug–drug interactions.
Why stereochemistry is important in drug metabolism?
What does enantiomeric excess tell?
Enantiomeric excess (ee) is a measurement of purity used for chiral substances. It reflects the degree to which a sample contains one enantiomer in greater amounts than the other. A racemic mixture has an ee of 0%, while a single completely pure enantiomer has an ee of 100%.
What is drug stereochemistry?
Stereochemistry is of critical importance to drug action because the shape of a drug molecule is an important factor in determining how it interacts with the various biological molecules (enzymes, receptors, etc.) that it encounters in the body.
What is the use of stereochemistry?
Using stereochemistry, chemists can work out the relationships between different molecules that are made up from the same atoms. They can also study the effect on the physical or biological properties these relationships give molecules.
Are enantiomers Superimposable?
Enantiomers are stereoisomers that are non-superimposable mirror images, meaning that one enantiomer will be the mirror image of the other enantiomer.
What is stereoselectivity in chemistry?
In chemistry, stereoselectivity is the property of a chemical reaction in which a single reactant forms an unequal mixture of stereoisomers during a non- stereospecific creation of a new stereocenter or during a non-stereospecific transformation of a pre-existing one.
What is the difference between stereoselectivity and stereoconvergence?
Stereoconvergence can be considered an opposite of stereoselectivity, when the reaction of two different stereoisomers yield a single product stereoisomer. The quality of stereoselectivity is concerned solely with the products, and their stereochemistry.
What is the stereoselectivity of E2 reaction?
Stereoselectivity means the specific formation of either (E) – or ( Z )-alkenes. Unlike the E 1-reaction, which has only poor stereoselectivity because of the intermediate formation of a planar carbocation, the stereoselectivity of the E 2 reaction is very high. In the transition state all five groups or atoms involved must be coplanar.
What is the difference between steric and electronic selectivity?
The selectivity arises from differences in steric effects and electronic effects in the mechanistic pathways leading to the different products. Stereoselectivity can vary in degree but it can never be total since the activation energy difference between the two pathways is finite.