A rigid redox-active-ligand-supported bis(germylene) as a two-centre six-electron donor.

A naphthyridine diimine (NDI) supported bis(germylene) NDI-Ge2 containing two dicoordinate, coplanar Ge(II) atoms has been synthesised. Computational investigations on NDI-Ge2 indicated the two Ge(II) atoms are nearly independent. The EDA-NOCV analysis of the [NDI-Ge2][Fe2(CO)6] complex revealed the six-electron donor behavior of NDI-Ge2, the first example for group-14-element-based bidentate ligands.

Dichloromethyllithium: Synthesis and Application in Continuous Flow Mode.

A simple and robust procedure for the synthesis and use of thermally unstable dichloromethyllithium in continuous flow mode is described. By utilizing residence times in the range of milliseconds for the generation and electrophilic quench of dichloromethyllithium, the straightforward synthesis of dichlorocarbinols and benzylic pinacol esters was realized at reaction temperatures of -30 °C, whereas typical temperatures in traditional batch mode are below -78 °C. The excellent purity profile obtained from the flow process allows us to directly telescope the exiting flow stream into semibatch quenches for further modifications. All transformations gave the desired products in remarkable purity and yield on gram scale with no need for chromatography.

Flow Chemistry on Multigram Scale: Continuous Synthesis of Boronic Acids within 1 s.

The benefits and limitations of a simple continuous flow setup for handling and performing of organolithium chemistry on the multigram scale is described. The developed metalation platform embodies a valuable complement to existing methodologies, as it combines the benefits of Flash Chemistry (chemical synthesis on a time scale of <1 s) with remarkable throughput (g/min) while mitigating the risk of blockages.

Iterative reactions of transient boronic acids enable sequential C-C bond formation.

The ability to form multiple carbon-carbon bonds in a controlled sequence and thus rapidly build molecular complexity in an iterative fashion is an important goal in modern chemical synthesis. In recent times, transition-metal-catalysed coupling reactions have dominated in the development of C-C bond forming processes. A desire to reduce the reliance on precious metals and a need to obtain products with very low levels of metal impurities has brought a renewed focus on metal-free coupling processes. Here, we report the in situ preparation of reactive allylic and benzylic boronic acids, obtained by reacting flow-generated diazo compounds with boronic acids, and their application in controlled iterative C-C bond forming reactions is described. Thus far we have shown the formation of up to three C-C bonds in a sequence including the final trapping of a reactive boronic acid species with an aldehyde to generate a range of new chemical structures.

ortho-Perfluoroalkylation and ethoxycarbonyldifluoromethylation of aromatic triazenes.

A robust protocol for perfluoroalkylation and ethoxycarbonyldifluoromethylation of functionalized aromatic triazenes is described. Using silver(I)-fluoride and different fluorinated (trimethyl)silyl substituted species, it was possible to synthesize various ortho-fluorinated triazenes in good yields via simple CH-substitution. Initial reactions under solvent-free (neat) conditions indicate a stabilizing interaction between "AgRf" and the triazene moiety, which may be responsible for the good yields and regioselectivity. The transformation possibilities of the triazene moiety make these reactions interesting for the synthesis of fluorinated building blocks. In addition, quantum chemical calculations suggest that the stabilization of the radical intermediate in the ortho-position is distinctly more favored for aromatic triazenes than for other aromatic substrates.

Silver-mediated methoxycarbonyltetrafluoroethylation of arenes.

In the presence of silver(I) fluoride, highly fluorinated olefins react readily under solvent-free conditions with arenes via CH-substitution. This transformation could be used to synthesize various methoxycarbonyltetrafluoroethylated aromatic triazenes and anisoles under high functional group tolerance. The method could be applied to the synthesis of a formal fluorinated bioisostere of the NSAID flurbiprofen. To the best of our knowledge, this is the first example which uses highly fluorinated olefins for the perfluoroalkylation of aromatic substrates.

Synthesis of polypyrrole-coated core/shell nanoparticles.

The synthesis, physical characterization and scale-up of conductive, re-dispersible core/shell nanoparticles containing polypyrrole (PPy) in the shell are described. The compressed powders/films show a DC conductivity which is considerably higher than that of commercial standard products based on PEDOT/PSS ('AL 4083' from H.C. Starck). The particles have excellent film-forming properties since thin films (50-100 nm) made by spin-coating from aqueous dispersions of the particles have an AFM film roughness of <15 nm even before annealing. The materials were tested as hole injection/smoothening layers in fluorescent OLED devices, and are in a comparable range to PEDOT/PSS-based materials in respect to performance (film forming, luminance, efficiency, and lifetime).

Highly enantioselective catalytic asymmetric synthesis of a (R)-sibutramin precursor.

The first highly enantioselective, catalytic asymmetric synthesis of di-des-methylsibutramine 3 is described. Dienamide 10, prepared by acetic acid anhydride quenching of the condensation product of nitrile 4 with a methallyl magnesium chloride, proved to be an excellent substrate for ruthenium-catalyzed asymmetric hydrogenation with atropisomeric diphosphine ligands. Hydrogenation with a ruthenium/(R)- MeOBiPheP catalyst at S/C = 500, gave the chiral amide (R)-9 in 98.5% ee in almost quantitative yield. After acidic amide hydrolysis the desired amine (R)-3 was obtained without erosion of enantioselectivity. It is anticipated that the overall process will be amenable to large-scale production.

Biocatalytic deuterium- and hydrogen-transfer using over-expressed ADH-'A': enhanced stereoselectivity and 2H-labeled chiral alcohols.

Employing the over-expressed highly organic solvent tolerant alcohol dehydrogenase ADH-'A' from Rhodococcus ruber DSM 44541, versatile building blocks, which were not accessible by the wild type catalyst, were obtained in > 99% e.e.; furthermore, employing d8-2-propanol as deuterium source, stereoselective biocatalytic deuterium transfer was made feasible to furnish enantiopure deuterium labeled sec-alcohols on a preparative scale employing a single enzyme.