Gunther Lohmer

A New Catalyst System for the Heck Reaction of Unreactive Aryl Halides

A simple solution to the age-old problem of the Heck reaction of cheap but unreactive chloro- and bromoarenes [for example, reaction (1)] has been found in the catalyst [Pd(CH3 CN)2 Cl2 ]⋅6 Ph4 PCl in the presence of N,N-dimethylglycine as additive. The reaction then proceeds with exceptionally high efficiency.

A HIGHLY ACTIVE PHOSPHINE-FREE CATALYST SYSTEM FOR HECK REACTIONS OF ARYL BROMIDES

Abstract Palladium salts such as Pd(OAc) 2 or PdCl 2 (PhCN) 2 in the presence of N,N -dimethylglycine (DMG) constitute the simplest and one of the most reactive and selective catalyst systems for the Heck reaction of aryl bromides with olefins known to date.

Propylene carbonate stabilized nanostructured palladium clusters as catalysts in Heck reactions

Nanostructured Pd clusters, prepared either electrochemically using a sacrificial Pd anode or by thermolysis of Pd(O2CMe)2, are stable in propylene carbonate even at 140–155 °C; such colloidal solutions catalyse Heck reactions in the absence of phosphine ligands.

Separation and Identification of Basic Dendrimers Using Capillary Electrophoresis On‐line Coupled to a Sector Mass Spectrometer

The on-line coupling of capillary electrophoresis (CE) with a sector mass spectrometer via an electrospray ionization (ESI) source has been used to separate and identify polydisperse dendrimeric diaminobutane (DAB)-based polynitriles. A sample of the corresponding second generation has been analysed and revealed to be a complex mixture of the product, DAB-dendr-(CN)8 accompanied by several by-products. The capillary electrophoresis/mass spectrometry (CE/MS) data, including the reconstructed-ion current, the mass spectra and the UV-trace, provided fast and detailed information concerning the heterogeneity of the sample. The respective ESI mass spectra are dominated by the [M+H]+, [2M+H]+ and/or [M+2H]2+ peaks. The mass resolution of the sector mass spectrometer requiring m/Δm=2000, easily allowed signals of doubly charged ions to be assigned. CE/MS proved to be a promising tool with regard to the efficient analysis of basic dendrimers.

Ein neues Katalysatorsystem für die Heck-Reaktion von reaktionsträgen Arylhalogeniden

Eine einfache Losung fur ein altes Problem: Die Heck-Reaktion der billigen, aber wenig reaktiven Arylchloride [Gl. (1)] und -bromide wird mit dem Katalysator [Pd(CH3CN)2Cl2]⋅6 Ph4PCl in Gegenwart von N,N-Dimethylglycin als Additiv mit ungewohnlich hoher Effizienz moglich.