MCAT-53™: An Air Stable Arene Ruthenium Catalyst for C–C Cross-Coupling

Application

MCAT-53™is a proprietary recyclable ruthenium-containing catalyst for C–C coupling reactions in aqueous media. In contrast to Pd-catalyzed C–H activated and directing group (DG) directed C–C coupling reactions, MCAT-53™ achieves C–H-activated C–C coupling in water under ligand-free conditions, requiring no auxiliary oxidants (such as Copper(II) salts and Silver(I) salts, or benzoquinone). The catalyst is tailor made to work in distilled / deionized water.

This first of its class, bench- and air-stable, MCAT-53™ will find wide utility in cost-effective and greener alternatives in manufacturing processes in the chemical enterprise. This catalyst that manifests its action in aqueous solutions has been developed by Chicago Discovery Solutions, USA.

Typical Reaction

The catalyst MCAT-53™ is added to the mixture of two aryl moieties (variously substituted) to get C–C coupling in water such as DG directed C–H activated C–C coupling.

MCAT-53™ reaction

Representative Example

To a reaction flask equipped with a stirring bar and a reflux condenser, was added substrate (e.g. 2-Phenyl pyridine, 1.0 mmol and 5 ml water (DI/ distilled water) followed by sequential addition of potassium carbonate (2 mmol) and aryl bromide (2.5 mmol). 40 mg MCAT- 53™ Ruthenium catalyst (0.07 mmol) is added immediately to the slightly cloudy mixture. The orange brown solution is heated to reflux (turns black) and allowed to stir vigorously for 1 to 6 hrs. Typically, the amount of aryl chloride and the heating time determines the ratio of mono and diarylated products. The heterogeneous reaction mixture is then diluted with a minimum amount of EtOAc. The ethyl acetate layer is separated, washed with brine and dried over sodium sulphate. The volatiles are removed to afford the crude product, which is subsequently purified by filtration over a small silica gel plug or flash chromatography on silica gel as required. Recycle and reuse of aqueous layer: The aqueous layer was further washed with EtOAc and can be saved for the next time to perform the experiment again.

Materials

     
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