Publication

Fluorinated analogs of retinoids. Stereocontrolled synthesis employing fluoroisoprenoidal Horner ylides

Manfred Schlosser
1998
Journal Articles

Abstract

An improved method for the prepn. of Me2C:CFCO2Et is described. The two stereoisomers (E)- and (Z)-BrCH2CMe:CFCO2Et obtained by g-bromination are sepd. and can be individually converted into the corresponding phosphonates. The PO-ylides generated by a-deprotonation of the latter lose their stereochem. integrity by rapid torsional equilibration of the ester tail. Thus, Horner-Wittig reactions accomplished with PhCHO and (Z)- or (E)-(b-ionylidene)acetaldehyde lead inevitably to stereo-randomization at the terminal, CO2Et-bearing double bond affording (E)- and (Z)-isomers in 50:50 to 15:85 ratios, depending on the reaction conditions. The new double bond, however, is formed with perfect trans-selectivity. [on SciFinder (R)]

Official source

https://infoscience.epfl.ch/entities/publication/9ed188bd-9aa6-48c7-98b7-c83f5badaa0b

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Manfred Schlosser
1998
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/9ed188bd-9aa6-48c7-98b7-c83f5badaa0b

About this result

Related concepts (21)

Double bond

In chemistry, a double bond is a covalent bond between two atoms involving four bonding electrons as opposed to two in a single bond. Double bonds occur most commonly between two carbon atoms, for example in alkenes. Many double bonds exist between two different elements: for example, in a carbonyl group between a carbon atom and an oxygen atom. Other common double bonds are found in azo compounds (N=N), imines (C=N), and sulfoxides (S=O).

Bent bond

In organic chemistry, a bent bond, also known as a banana bond, is a type of covalent chemical bond with a geometry somewhat reminiscent of a banana. The term itself is a general representation of electron density or configuration resembling a similar "bent" structure within small ring molecules, such as cyclopropane (C3H6) or as a representation of double or triple bonds within a compound that is an alternative to the sigma and pi bond model.

Halogenation

In chemistry, halogenation is a chemical reaction that entails the introduction of one or more halogens into a compound. Halide-containing compounds are pervasive, making this type of transformation important, e.g. in the production of polymers, drugs. This kind of conversion is in fact so common that a comprehensive overview is challenging. This article mainly deals with halogenation using elemental halogens (). Halides are also commonly introduced using salts of the halides and halogen acids.