Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: orgobot on May 06, 2008, 07:39:42 PM
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Hi everyone,
I'm working on a synthesis problem that really looks like a Mannich reaction (ketone, formaldehyde, amine). The thing is we need to start with given molecules as our only carbon source. I'm given cycloheptene as a starting molecule but if it is a Mannich reaction, it looks like I need a cyclohexanone.
My question is, is it possible to synthesize cyclohexanone from cycloheptene? My first thought was ozonolysis --> aldol but then I'm stuck. I've also tried to figure out other ways that aren't Mannich reactions but I get stuck there. Does anyone have any hints in the right direction? Thanks :)
edit: my bad. I meant cyclohexanone, not cyclohexanal... :-X
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If you provide the structure, people would be able to say whether they agree with your choice of Mannich.
What about addition with an aqueous halogen, oxidation of the alcohol to a ketone and then favorskii rearrangement to get the carboxylic acid. If you need the aldehyde, reduce to the alcohol and oxidize with PCC.
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Apologies! First, I meant cyclohexanone, since Mannich needs a ketone.
I'm not sure how to properly name the structure, but it looks like the result of a Mannich given a cyclohexanone, formaldehyde, and a methyl amine.
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So...like this?
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yes, that is it.
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My question is, is it possible to synthesize cyclohexanone from cycloheptene?
1) Treatment with CrO2Cl2 in acetone to get 2-chlorocycloheptanone.
2) 2-chlorocycloheptanone + NaHO, then acidify, to get cyclohexanecarboxilic acid.
3) Br2, HgO, heat, to get cyclohexyl bromide.
4) Oxidation with DMSO to get cyclohexanone.
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Hi Yarr, thanks for the response. I don't think I've ever heard of CrOCl2, and we're only allowed to use reagents we know, though... Does anyone have other suggestions? Until then I'm going to keep working at it :)
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Hi Yarr, thanks for the response. I don't think I've ever heard of CrOCl2, and we're only allowed to use reagents we know, though... Does anyone have other suggestions? Until then I'm going to keep working at it :)
Surely if you are learning the mannich reaction you're able to use other reactants. If not, all the CrO2Cl2 does is what the first 2 steps of my synthesis does: chlorine water, then oxidation of the alcohol to a ketone. Which is where you are at for step 2 of Yarr's synthesis.
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Hello
I'm not quite sure what it is you're discussing here but one thing I got out of it was that you needed to synthesise cyclohexanone from cycloheptene and I have a suggestion on how to do that (see jpeg attached). Ozonolysis of cycloheptene and workup with hydrogenperoxide to the diacid. Esterification and treatment with base giving via a claisen (dieckmann) condensation a beta-keto ester, that after hydrolysis can be decarboxylated to give cyclohexanone.
Rico