Went to look for material on C-H microwave-assisted insertion reactions and was quite surprised that so little has been published. With all of the aromatic, heteroaromatic and constrained aryl compounds, I figured people would be licking their chops to get at it — as the holy grail of organometallic catalysis. Well then — one would think that the lack of functional leaving groups needed or aryl boronic acids, halides and or a stoichiometric catalyst who wouldn’t give it a go. Maybe all of you are, but it is simply too boring to publish. Enough of my context: let’s look at a pretty cool C-H microwave insertion. Although this is not that new, it certainly makes me think there is work that can be applied in medicinal chemistry groups — c’mon just look at those screening hits begging.

Out of Bob Bergman and John Ellman labs at UC Berkeley in 2003, the C-H insertion under microwave irradition was investigated as a replacement for a high-temp sealed tube reaction. Several things were modified 1) Wilkinson’s catalyst to the Rh (coe) catalyst shown in the scheme which provided lower loading 2) solvent was swtiched to dichlorobenzene with acetone (for microwave absorbing power — but can be modified now to move away from acetone if needed but at 6-12 minute reaction times, who’s telling them to change and 3) reaction times from hours to minutes. Enjoy the reading — I will have more of a review on this transformation in the future.

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Microwave Intramolecular C-H insertion

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