[ArchStanton]

I am trying to make a thiazole stannane on a small scale (less than 500 mg as the sm is very expensive). It will not run down a column and in its crude form the following coupling reaction doesn't work.

Any one got any ideas or experience in this area?

I still need some answers to my survey. Your help is greatly appreciated and there is a cash prize

http://www.surveymonkey.com/s.aspx?sm=k7GRM5tnVhwmoMuVDi7NmQ_3d_3d

[kiwi]

can you sketch out the stannane and its coupling partner?

[ArchStanton]

I have attached the structures.

Thanks

[kiwi]

do you need the stannane for that? I'm not sure off the top of my head, but i think at least some thiazoles can be functionalised at that position by C-H activation.

[ArchStanton]

do you need the stannane for that? I'm not sure off the top of my head, but i think at least some thiazoles can be functionalised at that position by C-H activation.

You are right, they can be. Thats something we might do if this doesn't work.

There is a series of nice papers, detailing aryl iodide couplings with thiazole. (Org. Lett., 2008, 10 (13), pp 2909–2912, J. AM. CHEM. SOC. 2003, 125, 1700-1701)  There are regio chemical issues with the 4/5 position being substituted as well. Also a range of conditions have been reported so we thought we would try the easy option. As always with chemistry that NEVER works out.

[kiwi]

Indeed. The more convoluted and painful a route is, the more likely it will work out.

There is some nice work with Ru catalysts (or was it Rh?) that can C-H functionalise a variety of azoles; from memory thiazoles were not so good yield wise but I think they worked. The functionalisation goes via the coordinated N-heterocyclic carbene in this system, so I'd expect selectivity to be very good for C2. I'll see if I can think of the ref.
NB: I've done a (non-Stille) Pd coupling on a similar iodide to yours, and the N(Boc)2 protected iodide behaved very nicely.