Dmitri V. Sevenard

The first example of a preparative 1,4-perfluoroalkylation using (perfluoroalkyl)trimethylsilanes ☆

Abstract Reactions of 2-perfluoroalkylchromones with (perfluoroalkyl)trimethylsilanes proceed as a 1,4-nucleophilic perfluoroalkylation to give 2,2-bis(perfluoroalkyl)chroman-4-ones in high yields after acid hydrolysis. Oxidation of 2,2-bis(trifluoromethyl)-6-methylchroman-4-one with K 2 S 2 O 8 leads to fluorinated analogs of natural lactarochromal and the corresponding acid.

Synthesis of 2-(trifluoromethyl)-1,2-dihydro-4H-thieno[2,3-c]chromen-4-ones and 2-(trifluoromethyl)-4H-thieno[2,3-c]chromen-4-ones from 2-trifluoromethylchromones and ethyl mercaptoacetate

The redox reaction of 2-trifluoromethylchromones with ethyl mercaptoacetate in the presence of triethylamine results in the formation of 1,2-dihydrothieno[2,3-c]chromen-4-ones and diethyl 3,4-dithiadipate in high yields. Oxidation of the first compounds with nitrogen dioxide gave 1,2-dihydrothieno[2,3-c]chromen-3,4-diones which were converted into thieno[2,3-c]chromen-4-ones.

Unexpected synthesis of dihydrothienocoumarin derivatives from 2-trifluoromethylchromones and ethyl mercaptoacetate

The redox reaction of 2-trifluoromethylchromones with ethyl mercaptoacetate in the presence of triethylamine results in the formation of dihydrothienocoumarin derivatives and diethyl 3,4-dithiadipate in high yields.

2-Trifluoromethyl-1,3-dithianylium triflate: a convenient ‘masked’ electrophilic pentafluoroethylation reagent

With 2-trifluoromethyl-1,3-dithianylium triflate for the first time the synthesis, isolation and full structural characterization of an α-perfluoroalkylcarbenium salt was achieved. The title compound can be easily obtained on a preparative scale. The thermally stable dithianylium salt in combination with fluorodesulfurization chemistry is a promising novel reagent for the electrophilic polyfluoroalkylation of organic substrates, demonstrated by the pentafluoroethylation of O-nucleophiles.

First example of regioselective nucleophilic 1,6-addition of trimethyl(trifluoromethyl)silane to 4H-chromene derivatives

Condensation of 2-trifluoromethylchromone with diethyl malonate, ethyl cyanoacetate, and Meldrum’s acid gave the corresponding methylidene derivatives of 2-trifluoromethyl-4H-chromene. Nucleophilic 1,6-addition of an excess of Me3SiCF3 in the presence of Me4NF to those obtained from the former two compounds afforded 4-substituted 2,2-bis(trifluoromethyl)-2H-chromenes.

3-Polyfluoroalkyl-substituted E-cinnamic acids: easy access via Perkin reaction

Abstract 3-Polyfluoroalkyl-( E )-cinnamic acids being very useful building blocks were obtained by a simple and convenient one-step procedure. The Perkin type reaction of fluoroacyl-substituted arenes gives the titled compounds in good yields and excellent stereoselectivity independent on the electronic nature of substituents in the aromatic ring. In the case of fluoroalkyl–alkylketones only O -acylation occures under the same conditions.

Continuous-flow synthesis of fluorine-containing fine chemicals with integrated benchtop NMR analysis

A compact lab plant was designed for the continuous-flow synthesis of fluorine-containing compounds and was combined with an NMR analysis platform based on a benchtop NMR spectrometer. The approach of a unified synthesis and analysis strategy for fine chemicals was applied to three different reactions, all employing fluorine as a chemical probe for online-19F NMR analysis. A high temperature synthesis for the deprotection of a CF2H group was done as well as Ruppert–Prakash reactions for the perfluoroalkylation of benzaldehyde as a model substrate. The C–H arylation of furan with a trifluoromethylated aryldiazonium salt was performed as an example of a photochemically catalyzed reaction. All three reaction classes challenge the synthesis and analysis setup differently according to sample preparation (premagnetization of bubble-free sample) and spectrometer sensitivity (signal to noise ratio, spectral resolution, scan number, substrate concentration and flow rate), but nonetheless prove the successful application of the continuous-flow synthesis of fluorinated fine chemicals with integrated online NMR analysis.

3-Polyfluoroacylmethylenephthalides: Synthesis and Structure

3-Polyfluoroacylmethylenephthalides (RF = CF3, CF2CF2H, C2F5) can be synthesized conveniently by cyclodehydration of 1-(2-carboxyphenyl)-3-polyfluoroalkylpropane-1,3-diones, obtained from o-acetylbenzoic acid and polyfluorinated esters, as a separable mixture of Z- and E-isomers. In solution, the Z- and E-isomers of 3-polyfluoroacylmethylenephthalides are interconvertable. For CD3CN and (CD3)2SO solutions of 1-(2-carboxyphenyl)-3-polyfluoroalkylpropane-1,3-diones a ring–chain tautomerism is observed. The structures of the new compounds have been determined by heteronuclear nuclear magnetic resonance (NMR) spectroscopy and nuclear Overhauser effect (NOE) experiments.

Metal and Boron Derivatives of Fluorinated Cyclic 1,3-Dicarbonyl Compounds

Starting from the corresponding cyclic 1,3-diketones or other precursors (cyclic ketones as well as lactones), several new salts and chelate complexes of fluorinated 1,3-dicarbonyls were obtained. Their preparative significance was demonstrated by straightforward syntheses of fluorinated pyrazoles, benzimidazoles and 1,7-ketoesters. The structure of a boron chelate of 2-(trifluoroacetyl)- cyclohexanone was investigated by X-ray diffraction. Graphical Abstract Metal and Boron Derivatives of Fluorinated Cyclic 1,3-Dicarbonyl Compounds

Fluorotris(trifluoromethylsulfonyl)methane: synthesis, characterization and reactivity

Abstract The hitherto elusive title compound was synthesized and characterized with the aim to study its potential as a carbon-based (“CF-type”) electrophilic fluorination reagent. A detailed discussion of its structure, properties and reactivity is based on experimental studies as well as on molecular modeling.