Friday, February 15, 2013

Friday Fun: All Your Base Are Belong to MOBBs

(With apologies to Ohio)...What's round in the middle and "I" on both ends?

It's a twist!
How does that biaryl bond survive?
Source: OL | ICIQ
If you guessed the newly-reported mu-oxo bridged bisiodones (MOBBs?) reported in Org. Lett., you win. We're all familiar with famous mono-hypervalent iodine reagents: IBX, Togni reagents, iodosobenzene, Dess-Martin, etc., but I'll admit this is the first time I've seen them 'doubled up' like this.

So, aside from a mangled crystal structure - which, if you believe it, almost folds the biaryl in half -  this reagent seems predisposed to rearrange itself in situ, forming a charged pair: [O=I-biaryl-I-NTs2(+)] NTs2(-). Thus, the same molecule decomposes into electrophilic and nucleophilic bis-tosylimides, which can be used to diaminate simple olefins.

Pretty schnazzy.

Now, that's a load of atomic mass to drag around for just two simple C-N bonds. Can we do better? Sure - the researchers demonstrate some early catalytic runs, and along the way swap out the biaryl for a chiral binaphthyl (c'mon, you saw that coming), which induces a proof-of-concept 32% ee.

I'll admit it: when I first saw this abstract pass by, I thought not of reactions but of...invaders. Specifically, Space Invaders, the formative 1978 Atari arcade game where your blocky white tank takes aim at dozens of 8-bit baddies falling from the sky. To me, the fully-formed reagent looks just like the "middle" guy in that picture (see below).


Credit: Atari
Happy synthesizing, happy gaming, and happy Friday!
-SAO

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