Publication

Stereoselective synthesis of new 8-oxabicyclo[3.2.1]oct-6-en-2-one and 8-oxabicyclo[3.2.1]octa-3,6-dien-2-one derivatives. The electron-releasing and electron-withdrawing effects of homoconjugated ketones

Pierre Vogel
2001
Journal Articles

Abstract

Two successive brominations of 8-oxabicyclo[3.2.1]oct-6-en-2-one 6 provided 3-exo,6-exo,7-endo-tribromo-7oxabicyclo[3.2.1]octan-2-endo-one 10 with high stereoselectivity. NaBH4 reduced 10 into 3-exo, 6-exo,7-endo-tribromo-8-oxabicyclo[3.2.1]octan-2-endo-ol exclusively. Selective elimination of one equivalent of HBr from 10 furnished 3-exo,7-dibromo-8-oxabicyclo[3.2.1]oct-6-en-2-endo-ol 13. Regio- and stereoselective addition of PhSeCl to enone 6, followed by alpha -ketone bromination and treatment with a base led selectively to 7-(phenylseleno)-8-oxabicyclo[3.2.1]octa-3,6-dien-2-one 20. The high selectivities observed are attributed to steric factors and to electronic factors such as electron-releasing or electron-withdrawing effects of homoconjugated carbonyl group.

Official source

https://infoscience.epfl.ch/entities/publication/2c76aa5f-1c32-40d1-ae21-3b43e6793245

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Pierre Vogel
2001
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/2c76aa5f-1c32-40d1-ae21-3b43e6793245

About this result

Related concepts (23)

Stereoselectivity

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. The selectivity arises from differences in steric 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: both products are at least possible and merely differ in amount.

Enantioselective synthesis

Enantioselective synthesis, also called asymmetric synthesis, is a form of chemical synthesis. It is defined by IUPAC as "a chemical reaction (or reaction sequence) in which one or more new elements of chirality are formed in a substrate molecule and which produces the stereoisomeric (enantiomeric or diastereomeric) products in unequal amounts." Put more simply: it is the synthesis of a compound by a method that favors the formation of a specific enantiomer or diastereomer.

Inductive effect

In chemistry, the inductive effect in a molecule is a local change in the electron density due to electron-withdrawing or electron-donating groups elsewhere in the molecule, resulting in a permanent dipole in a bond. It is present in a σ (sigma) bond, unlike the electromeric effect which is present in a π (pi) bond. The halogen atoms in an alkyl halide are electron withdrawing while the alkyl groups have electron donating tendencies.

Related publications (1)

Stereoselective synthesis of new 8-oxabicyclo[3.2.1]oct-6-en-2-one and 8-oxabicyclo[3.2.1]octa-3,6-dien-2-one derivatives. The electron-releasing and electron-withdrawing effects of homoconjugated ketones

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