Monofluorination of Organic Compounds: 10 Years of Innovation.

Metal complexes with open coordination sites have found
wide use in molecular recognition. They serve as binding
sites in the development of chemosensors to study metalloenzyme
function in bioinorganic chemistry or to direct
supramolecular self-assembly. Lewis-acidic metal complexes can target a large variety of Lewis basic functional groups,
which makes them very suitable for the design of synthetic
receptors. Coordination to metal ions occurs typically with large enthalpies compared to those for hydrogen bond
formation, salt-bridges, or dipole-dipole interactions.

Reversible coordinative bonds in molecular recognition.

α-Fluorination of β-ketosulfones by Selectfluor™ F–TEDA–BF4

A new highly efficient method for the synthesis of 2-fluoro-2-nitrostyrenes was described. Radical nitration of readily available 2-bromo-2-fluorostyrenes with Fe(NO3)3·9H2O resulted in the formation of the corresponding α-fluoro-nitroalkenes in isolated yields up to 92%. The reaction proceeded as a nitration-debromination sequence to highly stereoselectively give α-fluoro-nitroalkenes as Z-isomers only. The broad scope of this method was demonstrated. Prepared monofluorinated alkenes were shown to be versatile building blocks for the synthesis of various fluorinated products.

Radical Nitration-Debromination of α-Bromo-α-fluoroalkenes as a Stereoselective Route to Aromatic α-Fluoronitroalkenes—Functionalized Fluorinated Building Blocks for Organic Synthesis

Direct preparation of 1,3-dichloro-2-propanol from glycerol is carried out in a batch reactor using acetic acid catalyst at 363−393 K. The analytical technique, gas chromatography, is employed in order to follow the time evolution of the reagents. The kinetic model of the process is developed. Furthermore, the model parameters of the process are also determined by data fitting. The results show that direct preparation follows the SN2 mechanism. A kinetic model corresponding to the mechanism is proposed in this work. The experimental results show that the kinetic model agrees well with the experiments.

Direct Preparation Kinetics of 1,3-Dichloro-2-propanol from Glycerol Using Acetic Acid Catalyst

Fluorination and chlorination of nitroalkyl groups

Synthesis of 2-(nitromethyl)ornithine from ornithine mediated by cobalt(III).

Biological Organometallic Chemistry of B12

Sonochemical fluorination of heterocyclic nitro compounds with Selectfluor

Heterocycles substituted with a nitromethyl (CH2NO2) or phenyl-nitromethyl (CHPhNO2) group were prepared by reaction of a methyl- or phenylmethyl-substituted heterocycle, respectively, with lithium di-isopropylamide followed by quenching the intermediate carbanion with methyl nitrate. Conversion of CH2NO2 attached to an alkyl or aryl moiety into a dichloronitromethyl (CCl2NO2) group was achieved using N-chlorosuccinimide and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in dichloromethane. Similarly, CH2NO2 attached to an alkyl or aryl group was converted into difluoronitromethyl (CF2NO2) using either 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor™) or N-fluorobenzenesulfonimide with DBU as base and dichloromethane as solvent. Reaction of ω-nitroacetophenone with Selectfluor/DBU in dimethylformamide followed by acidification and distillation gave the parent difluoronitromethane in a useful ‘one-pot’ procedure.

Philip Butler

Papers

Fluorination and chlorination of nitroalkyl groups

Synthesis of 2-(nitromethyl)ornithine from ornithine mediated by cobalt(III).

Biological Organometallic Chemistry of B12

Sonochemical fluorination of heterocyclic nitro compounds with Selectfluor

Fluorination and Chlorination of Nitroalkyl Groups.