Unlearn everything you thought you knew about selectivity and the Wacker oxidation. Grubbs comes out of the Nobel closet and gives us the anti-Markovnikov Wacker. Awesome!

Anti-Markovnikov Wacker oxidation
Org. Lett. Article ASAP (DOI: 10.1021/ol301240g)

Under strikingly simple conditions, Grubbs and co-workers are able to oxidize styrenes to give the aldehydes and not the ketones with astonishing selectivity (or shall we say specificity?), and in many cases in OK to great yields.

Who would have thought such a simple variation using everyday reagents, catalysts and solvents would turn things so drastically around? I am impressed. Really, really impressed.

Tutors and text book authors – you have work to do. Meth cooks – so do you.

 

7 Responses to Whacky Wacker

  1. Toya says:

    I’m hoping that meth cooks will never have the funding to purchase palladium catalysts.

  2. milkshake says:

    the Hive cooks of course found out about Wacker in 90s, as you can check out in the Rhodium archive on Erowid, and for safrole you actually do not need anti-Markovnikov version. The only issue was to find a trailer-lab friendly version with less Pd(II) loading, and to replace benzoquinone with another oxidant. BTW, did you know that one can use alkyl nitrites as the terminal oxidant in Wacker?

  3. Nice. It will be interesting to see what happens with alkenes that do not bear an aryl group. I’m particularly wondering about the intramolecular Wacker oxidation to make oxygen heterocycles.

    • drfreddy says:

      Treat your starting material under usual Wacker conds. and get a 5-membered ring. Or do the Whacky Wacker and get the corresponding 6-membered ring. I like it. A point of diversity.

      However, my gut feeling says this reaction is substrate dependent, and would require substantial optimization before it worked on aliphatics (if possible at all). If this paper has zero backrefs in a year or so, we know 🙂

      • BRSM says:

        Coincidentally, I used almost these exact conditions for on an allylnaphthalene a couple of years back, only in MeCN/H2O, if I recall correctly. Didn’t see any aldehyde. I’m sure the idea of trying it will have occurred to them and, unless they’re saving it for another paper, I guess it didn’t work.

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