Recent Illinois Chemistry

So…I barely have enough time to read blogs, much less contribute to my own. Still, I felt an urge to publicize the latest offerings from the UIUC organic department. First, and I know I’m on the bandwagon late on this one, is Aaron Finke’s Organic Letters paper on using Hartwig’s C-H activation chemistry to synthesize 1,3,5-phenylene dendrimers (for non-chemistry readers: really big molecules).

On JACS ASAP today is a paper by Eric Gillis from the Burke group, detailing the surprising stability of their MIDA-protected boronates under a number of common reaction conditions (most notably, oxidation and aldol conditions). The paper demonstrates that, by introducing MIDA early in a synthetic route, boron can be carried through a series of synthetic steps and finally deprotected to afford a product that can undergo cross coupling. The development of MIDA certainly represents a breakthrough in the iterative cross coupling of boronic acids, although I’m not on its nuts as much as some people are. Call me crazy, but I feel like iterative cross coupling is a smidge overrated.

For the uninitiated, iterative cross coupling is the repeated formation of C-C bonds via cross coupling of substrates with protected coupling functionality. To build up long chains of arenes or polyenes, you can just couple, deprotect, couple, deprotect, couple…you get the idea. In practice, of course, things get more difficult with each coupling, but theoretically this could be carried on FOREVER! It’s great for polymer chemistry, it’s neat, and it’s an Illinois thing; I’ll give it that. I’ve never been much for the latest thing. It’ll take a few more natural product syntheses, and a couple not from the Burke group, to convince me that this synthetic methodology will endure.

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8 Comments

  1. I’ve been finding more and more that organoboron compounds are the sh!t. Surprisingly, with all the things you learn about organoboron in undergrad, that they boron’d fly right off if you look at it cross-eyed, but it’s a fairly resilient functional group.

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  2. I suppose the fact that boron requires base to be activated towards coupling speaks to that as well. I just wish this chemistry would either catch on or die so that people would stop hyping it up so damn much around here…

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  3. while the MIDA protection of boronic acids does seem like it will be useful, this paper should not have been a JACS communication. compatibility of boron with all these transformation has been pretty well fleshed out by Molander for BF3K salts. I would have liked to see this as a JACS article, with more details and more examples

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  4. j–yes, actually very recently S-A started selling like 40 MIDA boronates for use in cross-coupling. It is cool chemistry, but there’s such a thing as too much of a good thing…it gets tiring hearing about it.

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  5. Tell me about it. My department is plagued by ionic liquids because one of the rather big names had a mediocre breakthrough. I get weird looks from visiting students when I tell people that I actually don’t care about imidazolium salts.

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  6. Oh and as for those MIDA boronates… they’re useful but not rock-solid, unfortunately. However, they are certainly better than the diaminonapthalene-based protected boronic acids of Suginome, which seem to fall apart spontaneously in solution and are soluble in approximately jack shit.

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