dormouse (Member)
04-19-00 07:41
No 122791
      Leukart-Wallach mechanism inquiry -rev drone  Bookmark   


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Author  Topic:   Leukart-Wallach mechanism inquiry 
rev drone
Member   posted 03-31-99 02:03 PM          
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Now here's a mental puzzle for all you fellow organic chemistry fanatics: the Leukart-Wallach reaction mechanism.
Recently, someone proposed the use of DMF with indole-3-acetaldehyde to form DMT. Now, there is plenty of precedence in the literature for this to go, but still to date, there seems no *universally* accepted mechanism for this to work. Now the Leukart is a sentimental favorite with some (not me), but how does it work -- even for making secondary amines like meth?

Which brings me back to my question: how would YOU rationalize the fact that when you combine an aldehyde or a ketone, DMF, 90% formic acid, and heat it at 190 deg C for a few hours, you get dialkyl tryptamines?


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-the good reverend drone


 
Wizard X
Moderator   posted 04-06-99 11:07 PM          
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This is very similar to the
ESCHWEILER-CLARKE METHYLATION REACTION
The intermediate immonium ion +N=CH2 (produced by reaction of aldehyde or ketone with a formamide) is reduced with formic acid to N-CH3 + CO2.
Other reducing agents are NaBH4 or NaBH3CN


 
rev drone
Member   posted 04-07-99 10:43 AM          
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Yes, the Eschweiler-Clarke is simply an inversion of the Leukart-Wallach, but what my question is is pertaining to actual mechanism. Try drawing an electron-pushing diagram for systems involving dialkylformamides, and see what happens -- this isn't half that straight forward.
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-the good reverend drone


 
Wizard X
Moderator   posted 04-08-99 07:33 PM          
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Drone : here is a Leuckart with dimethylformamide and formic acid I've used.
Mole ratios : 173gr (2.5 moles)dimethylformamide and 54gr (1 mole) of 85% formic acid. This is heated to 150-155 deg C
Over a period of 4-5 hour, a mixture of 1 mole of redistilled aldehyde, and 163gr (3 moles) of 85% formic acid through a dropping funnel. The water and formic acid which distil is discarded.

As for the mechanism I will send it to you as a jpg image file when I'm done.


Optimus Prime
Member   posted 04-10-99 04:59 PM          
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Include me also in the mailing please...
OP


Rhodium
Administrator   posted 04-11-99 03:02 AM          
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What kind of aldehyde have you used? 3-IAA?
 
rev drone
Member   posted 04-12-99 12:40 PM          
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So generally, how would you verbally describe the mechanism for this?
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-the good reverend drone


 
Wizard X
Moderator   posted 04-14-99 11:22 PM          
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Hope the JPG images are OK !
 
Optimus Prime
Member   posted 04-17-99 09:27 PM          
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Here are some refs for you also Boss... I have no access to tett or Bull jap or I would have scanned them...
Lukasiewicz, Tetrahedron, 1963, 19, 1789;
Oba; Sekiya Bull. Chem. Soc. Jpn. 1976, 49, 2485...

I can get the japanese translated if you can get the article...

OP


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