Questions tagged [stereoselectivity]
For questions about reactions that favour the formation of one or more stereoisomers.
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Cannot understand the stereospecificity and stereoselectivity of a compound formed in a reaction
How is the reaction given below stereospecific and stereoselective?
1,3,6-trimethylcyclohexene is treated with B2H6 followed by H2O2/NaOH/H2O.
Since trans and cis form in cycloalkene starts in a 8 ...
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Why is only the (E,E)-isomer obtained in Claisen-Schmidt condensation?
I added 2 equiv of p-tolualdehyde to 1 equiv of acetone to make (1E, 4E)-1,5-di-p-tolylpenta-1,4-dien-3-one (NMR backed it up). Why is this the only isomer formed? Just sterics or something more?
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Which substrates will undergo an E2 reaction to give a (Z) alkene?
What I do know: E2 reactions are concerted and have an anti-coplanar transition state, where the leaving group and the hydrogen being abstracted have a dihedral angle of 180 degrees.
What I don't ...
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Sn(II) compound stereoselectivity in aldol reactions
In "advanced organic chemistry: part B" fifth edition, page:130, the authors state that chiral proline-like additives to Sn(II) compounds can further increase stereoselectivity of aldol ...
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(How) can a reaction be both stereoselective and stereospecific?
From what I have learnt, stereospecific and stereoselective reactions are defined as follows -
Stereospecific - The stereochemistry of the reactant dictates the stereochemistry of the product. Thus, ...
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stereoselectivity in aldol reactions
in "Advanced Organic Chemistry, part B" fifth edition book, page:103, the authors compare between aldol reactions where 1-substituted nucleophile is used. They stated that when the 1-...
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Stereochemistry & mechanism of β-cyano enone methylation
I am helping a friend with some upper-level mechanism problems. We came across this one. This is my proposal. Do you agree/disagree? Thank you for any input.
Source question:
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How do electrostatic effects effect facial selectivity in addition to cyclic oxo-carbeniums?
I was reviewing Dave Evans' notes for stereochemistry of C=X electrophile additions, and found this slide detailing differences in additions to cyclic oxo-carbenium electrophiles, but I don't ...
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Does syn-dihydroxylation form racemic mixture?
I have been asked to determine the nature of the product for the following reaction:
And as I recognized this reaction to be a case of syn-dihydroxylation, my obvious response was that the product ...
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Hydroboration, steroselectivity and anti-markovnikov product [duplicate]
My first question has to do with the fact that Hydroboration produces an anti-markovnikov product, why?. I don't see how that happens. A wikipedia artical says that B has a partial positive charge ...
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Synthesis of Pt(II) complex using trans effect
By making use of the trans-effect in platinum(II) complexes, show efficient routes for the synthesis of all the possible isomers of $\ce{[PtCl(NH3)2(py)]+}$ (where $\ce{py}$ = pyridine) from the ...
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Stereoselectivity of ring closure in intramolecular iodolactonisation
What is the product of the reaction above?
I am mainly confused between the following two options:
How do we decide the resulting stereochemistry of the $\ce{CH_2I}$ group?
The answer given is the ...
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What is the meaning of pi selectivity?
I came across this term while going through a research paper for the first time of organic chemistry on diastereoselectivity of tricyclo[2.1.0.02,5]pentan-3-ones. I am not familiar with the term and ...
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Solvent shell collapse
In "advanced organic chemistry part A" book page:306&307 , the author uses the term 'solvent shell collapse' when talking about the reason for retention of conformation in tertiary ...
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Cram's rule vs Felkin Anh's model
I am getting two different products based on the Cram and Felkin-Anh models as shown in the diagram. Any explanation?
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