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Topic: Aromatic to Cyclohexane compound  (Read 8168 times)

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Offline enkay

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Aromatic to Cyclohexane compound
« on: August 21, 2006, 01:10:48 PM »
Hey friends !  :D

Is it possible to make :

4-Aminomethyl Cyclohexane Carboxylic acid      FROM     4-Aminomethyl Benzoic acid....?


Structural images for both compounds is attached here.

No such data in beilstein available for this route. Can anyone pls help me out for this ?


 ;)

Offline Will

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Re: Aromatic to Cyclohexane compound
« Reply #1 on: August 21, 2006, 01:25:24 PM »
I think hydrogenation with H2 and PtO2 in acetic acid at RTP would selectively reduce the benzene ring, I doubt you would just get that enantiomer though.

Offline Will

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Re: Aromatic to Cyclohexane compound
« Reply #2 on: August 21, 2006, 02:14:20 PM »
I am also aware hydrogenolysis could occur since you have a benzylic amine. I am not sure as to which catalysts this reaction can take place on, but I think Pd is one, so avoid that.

Offline HP

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Re: Aromatic to Cyclohexane compound
« Reply #3 on: August 21, 2006, 02:54:25 PM »
Birch reduction (reduction system Na/liquid NH3 in present of EtOH) is may be alternative hydrogenation but you must work with Na-salt of COO or it's ester. In this conditions the NH2 group may react with the alkali metal to form NH:-Na+ salt but with water it will back to NH2...Also the product of this reaction theoretically should be
1,4-cyclohexadien aduct which must be further hydrogenated easily with some nascent H source(may be Zn/HCl)...Well i am not sure in this synthetic route just discuss as posssible :)
xpp

Offline movies

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Re: Aromatic to Cyclohexane compound
« Reply #4 on: August 21, 2006, 06:47:52 PM »
I think hydrogenation with H2 and PtO2 in acetic acid at RTP would selectively reduce the benzene ring, I doubt you would just get that enantiomer though.

The product is achiral, actually, so no mixtures of enantiomers.  You might get a mixture of diastereomers though.  The diastereomer shown puts both groups equatorial though, so it might be preferred.

Offline Will

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Re: Aromatic to Cyclohexane compound
« Reply #5 on: August 21, 2006, 07:38:42 PM »
I think hydrogenation with H2 and PtO2 in acetic acid at RTP would selectively reduce the benzene ring, I doubt you would just get that enantiomer though.

The product is achiral, actually, so no mixtures of enantiomers.  You might get a mixture of diastereomers though.  The diastereomer shown puts both groups equatorial though, so it might be preferred.

I was hoping no one would notice that! A very bad mistake to make...
That diastereoisomer would be in equilibrium with the conformer which has both groups axial, but only about 2/3% would be in that conformation, the rest being both groups equatorial. I think it is safe to say that this diastereoisomer will definately be prefered, although you will still get some cis (s,s) product using this method.

Offline betterhb

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Re: Aromatic to Cyclohexane compound
« Reply #6 on: August 22, 2006, 01:57:20 AM »
I think this reaction is Birch reduction,you can search the reaction of Brich.

Offline HP

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Re: Aromatic to Cyclohexane compound
« Reply #7 on: August 22, 2006, 01:04:33 PM »
Heres the link for Birch reduction mechanism and examples:
http://www.organic-chemistry.org/frames.htm?http://www.organic-chemistry.org/namedreactions/birch-reduction.shtm
Look at reduction of benzoic acid which is possible with this method so i think it could be applied for this synthesis...Does someone have some experience or knowledge about further hydrogenation of 1,4 cyclohexadiene and it aducts  ???
xpp

Offline movies

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Re: Aromatic to Cyclohexane compound
« Reply #8 on: August 22, 2006, 03:48:22 PM »
The hydrogenation part after the Birch would be very easy.  The only trouble might be controlling the Birch itself.  It can be difficult to prevent side reactions or overreduction sometimes and also capturing the enolate with a proton might not work so well, I'm not sure.

Plus, if you've never done a Birch reduction on a free acid, it sucks.  A lot.

Offline HP

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Re: Aromatic to Cyclohexane compound
« Reply #9 on: August 24, 2006, 02:53:46 PM »
Hah but may be classics pretty working for orchestra of examples including this one :)
xpp

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