Facile Synthesis of 3,4-Dihydroxyamphetamine

[imp]

Hope this hasn't been posted before...

From JCS, pp. 2252, 1951.

1-(3:4-Dihydroxyphenyl)prop-2-ylamine. - A solution of veratraldehyde (8 g.), nitroethane (4 g.), and ammonium acetate (2 g.) in acetic acid (30 c.c.) was refluxed for 2 hours and then poured into water. The precipitated 1-(3:4-dimethoxyphenyl)-2-nitropropene formed yellow plates from ethanol, m.p. 73C.

The nitro-compound (6 g.) was placed in a small Soxhlet thimble and extracted under reflux into a solution of LAH (4.1 g.) in ether (200 c.c.), boiling being continued for 6 hours. The resulting ethereal suspension was decomposed with a concentrated solution of sodium potassium tartrate, the ethereal layer separated and dried, and the solvent removed. The residual oil, 1-(3:4-dimethoxyphenyl)prop-2-ylamine, distilled at 95-97C/0.05mm.

The amine (3 g.) was treated cautiously with hydrobromic acid (d 1.49; 10 c.c.) and refluxed 2 hours. The excess of acid was removed under reduced pressure and the residual gum crystallized on storage in a desiccator, giving the hydrobromide, which was washed with acetone.


Hmmm, just noticed Rhodium added a methylene sulphate synthesis to his website... interesting.
SWIM assumes we'll need some kind of amino protection, correct?

[Mountain_Girl]

"we'll need some kind of amino protection"

If you could sort that out [don't ask me how], this would be a possible route from eugenol to MDA [or MDMA via N-formyl-MDA].

[Rhodium]

Was there any yield mentioned for the demethylation step?

[Ganesha]

SWIM assumes we'll need some kind of amino protection, correct?

If you are generally afraid for the amine, you could reduce the C=C w/ sodiumborohydride, _then_ subject the formed _nitroalkane_ for demethylation w/ HCl, much more ghetto/easy. HBr yields probably better...

otc di-dealkylation:

Patent DE247906

= 3,4-dihydroxyphenetylamine from 3,4-dimethoxyphenetylamine w/ HCl

[Barium]

No need to protect the amine in the dealkylation-step. Nothing happens with it.

[imp]

SWIM guesses you guys didn't understand what was meant... Amino protection needed for methylenation to MDA, not for the dealkylation.

Rhodium, no yield was given.

love,
imp

[Barium]

Yes in the alkylation step the amine must be protected.

[Vitus_Verdegast]

I'm 100% sure I asked the same question before. Do they demethylate 4-methoxyamphetamine with HBr in that paper too? 

Somehow my brain tells me that yield was in the 50% area, I really hope I remember right.

I clearly remember suggesting to methylate eugenol as a precursor to MDA using above demethylation/methylenation. It must have been on the old board under my old username, since I cannot find it anymore.

I will now dive into my pile of papers and hope to find it back..

[Vitus_Verdegast]

..but I did find these at the patent office:

Patent GB482414

:

Example 1: 4-methoxy-N-methylamphetamine base is refluxed in an excess of 48% HBr for 1 hour. Yield of 4-hydroxy-N-methylamphetamine: 80-90%

Example 2: 4-methoxy-N-methylamphetamine base is dissolved in 5x the amount of conc. HCl and heated at 130°C in a sealed reactor for 1 hour. Yield: 90%

Example 3: If one substitutes the acids in the preceeding examples by HI/P, the yield is 90%

Patent US2015579

(by Gordon Alles):

While several procedures are possible, involving different acids and time of heating, this demethylation can be carried out with constant boiling hydrobromic acid (48%) in water in good yield in the following manner:

One mol of 1-(p-methoxyphenyl)-2-methylaminopropane, as the free base or as a salt such as the hydrochloride or hydrobromide, is dissolved in one liter of constant boiling aqueous hydrobromic acid solution (48%), and the mixture heated to boiling for four hours using a reflux condensor under atmospheric pressure. The water solution of the product, obtained by evaporation of the excess aqueous acid present, addition of water and decolorization with charcoal, is made alkaline with a concentrated aqueous sodium carbonate solution. The desired 1-p-(hydroxyphenyl)-2-methylaminopropane is precipitated as a gummy material which soon solidifies. this solid can be crystallized from ethanol, alone or with the addition of ether or benzene, or may directly be converted into an addition salt by combining it with an acid.

With the JCS article, and the patent Ganesha posted in mind, it can be assumed that 3,4-dihydroxyamphetamine or its N-methyl analog will give similar results.

This route may prove to be less problematic as a way to MDA than the eugenol demethylation, as mr. Alles has just demonstrated the scalability of it.