Reactions of aldehydes with cesium fluoroxysulfate
摘要:
Various aromatic and aliphatic aldehydes reacted at 35-40-degrees-C in CH3CN with CsSO4F giving acid fluorides in a good yield. In some cases formation of fluorohydrocarbons was also observed. Hammett correlation analysis of the transformation of various substituted benzaldehydes (p-OCH3, p-CH3, p-F, p-CF3, m-NO2) gave the reaction constant rho+ = -0.38. Solvent polarity strongly influenced the conversion of aldehydes into acid fluorides, being in acetonitrile almost quantitative and completely halted in CH2Cl2, n-hexane, or tetrahydrofuran. The presence of nitrobenzene, often used as a radical scavenger, considerably reduced the acid fluoride formation. Based on experimental observations was concluded that the main intermediates involved in the conversion of aldehydes into acid fluorides With CsSO4F must be of a radical nature.
<i>cis</i>-Specific Hydrofluorination of Alkenylarenes under Palladium Catalysis through an Ionic Pathway
作者:Enrico Emer、Lukas Pfeifer、John M. Brown、Véronique Gouverneur
DOI:10.1002/anie.201310056
日期:2014.4.14
paper describes the hydrofluorination of alkenes through sequential H− and F+ addition underpalladiumcatalysis. The reaction is cis specific, thus providing access to benzylic fluorides. The mechanism of this reaction involves an ionicpathway and is distinct from known hydrofluorinations involving radical intermediates. The first catalytic enantioselective hydrofluorination is also disclosed.
Stereospecific Electrophilic Fluorination of Alkylcarbastannatrane Reagents
作者:Xinghua Ma、Mohamed Diane、Glenn Ralph、Christine Chen、Mark R. Biscoe
DOI:10.1002/anie.201704672
日期:2017.10.2
Speed matters: Site-specific fluorination reactions of isolable primary and secondary alkylcarbastannatrane nucleophiles occur fast, without the need for transition metal catalysis, or in situ activation of the nucleophile. The reaction conditions can also be extended to stereospecific chlorination, bromination, and iodination reactions.
Transition metal-free cross-dehydrogenative arylation of unactivated benzylic C–H bonds
作者:Andrew R. A. Spencer、Rachel Grainger、Adyasha Panigrahi、Thomas J. Lepper、Katarzyna Bentkowska、Igor Larrosa
DOI:10.1039/d0cc06212j
日期:——
cross-dehydrogenative arylation of benzylic C–H bonds with arenes provides straightforward access to synthetically useful 1,1-diarylmethanes, from readily available starting materials. Current approaches suffer from limited substrate scope, requirement for large excesses of alkyl arene and/or non-trivial reaction set up. We report a transition metal-free cross-dehydrogenative arylation of benzylic C–H bonds using
Deoxyfluorination with CuF
<sub>2</sub>
: Enabled by Using a Lewis Base Activating Group
作者:D. Eilidh Sood、Sue Champion、Daniel M. Dawson、Sonia Chabbra、Bela E. Bode、Andrew Sutherland、Allan J. B. Watson
DOI:10.1002/anie.202001015
日期:2020.5.25
Deoxyfluorination is a primary method for the formation of C-F bonds. Bespoke reagents are commonly used because of issues associated with the low reactivity of metal fluorides. Reported here is the development of a simple strategy for deoxyfluorination, using first-row transition-metal fluorides, and it overcomes these limitations. Using CuF2 as an exemplar, activation of an O-alkylisourea adduct
Photoexcited acetophenone can catalyze the fluorination of unactivatedC(sp(3))-H groups. While acetophenone, a colorless oil, only has a trace amount of absorption in the visiblelight region, its photoexcitation can be achieved by irradiation with light generated by a household compact fluorescent lamp (CFL). This operational simple method provides improved substrate scope for the direct incorporation