Hey guys, I could really use your help. I have devised this wonderful novel route that gives desired in much fewer steps than before – with a small caveat. The final compound has a tin too many. As I cannot show you exact structures, this image will have to suffice. R is actually lots of things, such as fused ring and so forth.

protodestannylation

Lithiation followed by water or acid is out of the question, because of other labile groups. I spent some time in both SciFinder and Reaxys, and much to my surprise, I could not find a catalytic system that does what I want. Can this really be? I mean, I bet that if I would want to to use this material in a Stille coupling, at least 10 % of the protodestannylated product (which in our case is desired) would be one of the byproducts. I am surprised no one has figured out a way to do this catalytically – or my skills with our precious search tools are not what they once were. You tell me!

For aliphatic stannanes, I found this recipe in which you take your material in methanol and add TMSCl. Super-dry HCl thus forms in situ, and protodestannylates the product. But sp3 is not sp2.

If you happen to sit on a magic method or literature reference, the comment field is wide open! Thank you.

 

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—DrFreddy

10 Responses to Help me delete this tin

  1. Aryl stannanes can be protodestannylated with H-X, but with your pyridine nitrogen present, it may not be as easy as it looks. Easy to try, though. If that doesn’t work, your mention of the Stille coupling is a good lead. You would need H-Pd-X, which would cause transmetalation to give Bu3Sn-X and Ar-Pd-H, which would reductively eliminate. So, what are the ways (especially catalytically) to generate HPdX on purpose?

  2. FL says:

    I guess Pd(0) and R3SnH would generate a Pd-hydride complex, right? So what’s next? Would an excess of that specie transmetalate with your pyridylstannane and ultimately generate your desired compound and a Sn-Sn compound? Maybe there are other hydride sources that might be more favourable? I do like question marks, I must say.

    /FL

  3. FL says:

    Oops, didn’t mean to publish my full name, drfreddy could you please edit?

  4. milkshaken says:

    I wonder if aryl stannanes would come off with a protic fluoride source like aq. 40% HF + acetonitrile (or NEt3.3HF) – tributylstannyl has very high affinity to fluoride, KHF2 is commonly used in organotin workup.

    Also, if your molecule allows it, maybe you can just take a small sample and heat it to boil with Pd-C in water, to see what happens

  5. Belinda says:

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    Thanks for your effort ,Elijah

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