[biggestdav]

Hi, Im looking for a selective way to oxidize 2-amino 4,5 dimethyl furan 3 carbanitrile to the respective 2-nitro compound which I will convert to the 2 formyl compound for a wittig reaction. Does anyone know how to do this or even better is there a way to go directly from the amine to the formyl?

Thanks
Dave

[sjb]

Hi, Im looking for a selective way to oxidize 2-amino 4,5 dimethyl furan 3 carbanitrile to the respective 2-nitro compound which I will convert to the 2 formyl compound for a wittig reaction. Does anyone know how to do this or even better is there a way to go directly from the amine to the formyl?

Thanks
Dave

I can't see that being easy, especially with the furan there too (these tend to be fairly susceptible to oxidation, in my limited experience). What alkene are you looking at forming? How are you making the amino compound?

[biggestdav]

Thanks for your reply, the amine was commercially available so I just purchased it. The alkene will contain a further aromatic moiety (I cant go into too much detail!). I was thinking as an alternative to this method I could substitute the amine for a chloride by forming the zwitter ion using NaNO3, HCL followed by CuCl then reacting this product with Ph3P to make the ylide for the wittig reaction.

Any thoughts?

[sjb]

Ahh, catalogue curse. Whilst I see less problems with the formation of the chloride (do you mean diazonium, rather than the zwitterion?) I can't see a proton to deprotonate to form the ylide at that end

Might be worth a go the way you initially suggest then, perhaps with cold permanganate or similar - it's not as if the compound is several laborious steps down the route (for you, anyway). How do you propose forming the formyl from the nitro? The Nef will need an extra carbon, I think - perhaps a Henry or something, but there's still no alpha proton?

[biggestdav]

hmm this seems more difficult than I first thought!

I will do some lit searches and see what comes up

Thanks for your help sjb

[biggestdav]

After much searching ive had a few more ideas!

If I were to convert the furan amine to the chloride using a sandmeyer reaction http://en.wikipedia.org/wiki/Sandmeyer_reaction and then followed this with bouveault aldehyde synthesis http://www.springerlink.com/content/uwg601l111x21g87/ do you think this would provide a valid scheme to the formyl furan species?

[orgopete]

I don't think your Bouveault aldehyde syn is going to work with that nitrile. I think you can convert you amine into a bromide or iodide and either do a carbonylation or some masked carbonyl group. You might also go in the opposite direction by introducing a fluorine (or your chlorine) and do an addition-elimination with a carbonyl anion equivalent.

[kiwi]

After much searching ive had a few more ideas!

If I were to convert the furan amine to the chloride using a sandmeyer reaction http://en.wikipedia.org/wiki/Sandmeyer_reaction and then followed this with bouveault aldehyde synthesis http://www.springerlink.com/content/uwg601l111x21g87/ do you think this would provide a valid scheme to the formyl furan species?

You're on the right track, to save yourself a lot of trouble go for the iodide rather than the chloride (Knochel has published a simple one-pot amine->iodide prep). That then gives you a few more options for the metallation, first up I'd try low temp lithium-iodine exchange followed by quenching with DMF

EDIT: as pete has pointed out; you might get into trouble with that nitrile group. You might have to play with the grignard reagent (from iPrMgCl) or other electrophiles to get the best selectivity.

[biggestdav]

Thanks everyone for your help it is greatly appreciated!