Guo & Liu Catalyst

The literature train station is overflowing with diverse catalysts for the large variety of coupling reactions out there, as is the patent literature. Parties scramble to get window seats on the IP Express, the high speed non-stop to that Golden City on the Hill. 

A recent JOC article disclosing an inexpensive catalyst system that struck me as interesting.  The article by Guo and Liu emphasizes economy and so discloses a phosphorus-free bidentate ligand system that affords Heck and Suzuki-type coupled products.  There are pluses and minuses to this system, as is the case for most catalysts.

On the plus side with the Heck and Suzuki reactions, both activated and deactivated aryls gave decent yields. On the minus side, the Heck coupling reaction is a bit slow. A fair amount of energy input was needed- 130 C in DMF over 30 hours. On the Suzuki side, most reported reactions resulted in good yields, except for the aryl chlorides. The relative inertness of chlorides is not particularly unusual, but it may cause this catalyst to be passed over in some applications where the less atom-efficient bromides and iodides have been targeted for replacement.

Finally, the apparent requirement of DMF is rarely happy news. Regardless, I have no doubt that this catalyst will find its way into the future literature and many clever applications will be revealed.  As of this writing, I was unable to find a US patent by inventors Guo and Liu claiming this technology. Since there is a 1 year limit on the filing of a patent application following disclosure, this technology could be in patent prosecution at present. Or not. Wouldn’t it be a happy thing for it to be in the public domain?

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