[theufomusic]

Hello, Im just an Ex chemistry student (I completed second year, but didn't pass) and
im now wondering (just a thought experiment) if there is a way to completely cleave off
a carbonyl group and its carbonyl carbon; i.e Alpha cleavage (if I remember correctly.)

also, what would be a suitable reagent for performing this with an aromatic carbonyl?
Thankyou!

[movies]

You can sometimes decarbonylate aldehydes with Rhodium(I) catalysts.  Ketones are much more difficult.  You could consider Baeyer-Villiger oxidation followed by hydrolysis.

[nottingham]

You can sometimes decarbonylate aldehydes with Rhodium(I) catalysts.  Ketones are much more difficult.  You could consider Baeyer-Villiger oxidation followed by hydrolysis.

good idea.

[theufomusic]

Thanks! that might work.

[Custos]

You can sometimes decarbonylate aldehydes with Rhodium(I) catalysts.  Ketones are much more difficult.  You could consider Baeyer-Villiger oxidation followed by hydrolysis.

If you did a Baeyer-Villiger oxidation followed by hydrolysis on an aromatic ketone wouldn't you end up with the corresponding phenol? ... depending of course what was on the other side of the ketone - if the migratory ability of the other substituent was better than aryl you would end up with the arylcarboxylic acid which might decarboxylate. It's not really a decarbonylation though is it? Straight decarbononylation can be tough and it would depend on the specific example.

[theufomusic]

Its tryptophan, actually ...

[movies]

You can sometimes decarbonylate aldehydes with Rhodium(I) catalysts.  Ketones are much more difficult.  You could consider Baeyer-Villiger oxidation followed by hydrolysis.

If you did a Baeyer-Villiger oxidation followed by hydrolysis on an aromatic ketone wouldn't you end up with the corresponding phenol? ... depending of course what was on the other side of the ketone - if the migratory ability of the other substituent was better than aryl you would end up with the arylcarboxylic acid which might decarboxylate. It's not really a decarbonylation though is it? Straight decarbononylation can be tough and it would depend on the specific example.

Yes, you're absolutely right.  I was trying to come up with ways to cleave the C-C bond, which I think is the hardest part.  You would end up with an alcohol, and your options for reducing an alcohol to an alkane are a lot better (TsCl then LAH, Barton-McCombie deoxygenation, etc.).