Thursday, June 13, 2013

BuLi: Not Just a Base Anymore

When do you reach for that bottle of n-butyllithium at the back of the fridge? Making anions, sure, but BuLi's also great at ripping off halogens, destroying esters, alkylating imines, or swapping lithium for other metals (see: Sn, Zn, B, Cu, etc...).

What about using BuLi as an off-the-shelf cross-coupling partner? Sure, sounds like a methyl-ethyl-butyl-futile joke gone too far, but there're quite a few of those aryllithiums in catalogs nowadays...

Looks like Ben Feringa's got you covered. In Nature Chemistry, his group reveals that slow addition of a diluted organolithium to an aryl or vinyl bromide mixed with some electron-rich Pd(0) precatalysts provides alkylated products with high selectivity. At room temp. In one hour. In the presence of chlorides, esters, free alcohols, and all sorts of things that usually gum up the works. Zoinks!

I'll admit it - As someone who's spent a decent part of my life trying to glom one carbon onto another (grumbling while I purified yet another organotin or boronate), these initial results look promising. I'm sure they're furiously working on the alkyl-alkyl (sp3) coupling as we speak - good luck, that one's gonna be a lot harder.

P.S. Kudos for a well-thought-out Supporting Info section, too. The authors discuss their optimization process almost "stream-of-consciousness"-like, letting you vicariously learn the chemistry along with them.

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