Organometallics

 

By stringent definition, organometallics encompasses the study of organic compounds that contain a carbon-metal bond. It remarkably combines organic and inorganic chemistry into one beautiful mesh where really cool chemistry can occur. The literature is replete with examples of reactions that employ organometallic chemistry, many of which have been taught to undergraduates in their early-on exploration of chemistry (the very familiar Grignard reaction, Gilman reagent, Grubbs’s catalyst for olefin metathesis). But there’s so much more about organometallics than meets the eye (Paulson-Khand, Heck, Suzuki, Chan-Lam, Ullmann)! A timeline of the history of organometallics is shown below (source: Wikipedia): 

Our research group focuses on exploring organometallic methodologies, with special focus on metals like nickel, palladium, and copper (that mischievous blue fiend!). How I see our group’s study of organometallics is as a Nu-Nu cross coupling with the use of a lewis acid source to “connect” the two nucleophiles together.

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What’s interesting about this concept is that it seems counter-intuitive because reactions occur usually between electrophiles and nucleophiles. But organometallics transcends this “normality” and introduces a whole area of confusion that’s both fascinating and headache-inducing. My current project deals with copper, which, on the spectrum of chemistry history, does some weird and unusual transformations (Gilman reactions, 1,4 additions, SN2` additions). Furthermore, its oxidation states completely covers the range of Cu(0) —> Cu(+1) —> Cu(+2) —> Cu(+3), which is not too similar to Palladium’s oxidation state profile (Pd(0) —> Pd(+2) —> Pd(+4) (rarely occurs)). Why am I using copper? I’m trying to form vinyl ethers through the coupling of a pseudo-halide (boronate ester) with alcohols, targeting that C-O bond formation: 

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Why am I doing this? Well, although literature is full of ways to make vinyl ethers, many of these methods need extreme conditions – strong bases, strong acids, incredibly (well, not too incredible) high temp (>220C), and reactive electrophiles. Just look back at Fritz Ullmann’s work on aryl halide coupling using copper and you’ll see how harsh the conditions were. 

Fast-forward 97 years later to Chan, Lam, and Evans’s work on these copper-coupling reactions, and you’ll soon be stumbling into my research area, which is incredibly cool in my opinion. 

 

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Evans used Chan and Lam’s work to make thyroxine, a thyroid hormone agent.

 

 

I definitely need a greater foundation to shape up my misshapen understanding of organometallics, but I’m getting there.