Mono N-methylation
To a solution of the primary amine (0.002 mol) in anhydrous ethanol was added paraformaldehyde (0.002 mol). The resulting mixture was stirred at reflux for 1 h. The paraformaldehyde completely dissolved. Sodium borohydride (0.002 mol) was added and refluxed for 1 h. The solvent was removed; the residue was diluted with dichloromethane, washed with saturated aq. NaHCO3 solution, dried (Na2SO4) and evaporated to give the corresponding mono N-methyl product which was purified by silica gel column chromatography using a gradient of hexane and ethyl acetate (colorless oil, 74%).
References:
1.http://designer-drugs.com/pte/12.162.180.114/dcd/chemistry/amphetamine.methylation.html
2. http://www.alsnotebook.com/reductalk.html
3. Bhattacharyya, S. Synth. Commun. 1995, 25, 2061-2069.
what is your reference for the quote ……is there a problem with more than mono methylation of the amine? It’s assumed also that hydrogenation of the material with Pd as a catalyst will also give the desired mono methylated amine….?
J.R
April 8, 2008 at 9:59 am
Ref:
1.http://designer-drugs.com/pte/12.162.180.114/dcd/chemistry/amphetamine.methylation.html
and the references there in
2. http://www.alsnotebook.com/reductalk.html (procedure and mechanism)
3. Bhattacharyya, S. Synth. Commun. 1995, 25, 2061-2069.
We need the monomethylated product which cannot be accessed by using methyl iodide (overmethylation takes place).
Hydrogenation (Pd-C, H2) can also be used to reduce the imine intermediate (see Al’s notebook).
pmgb
April 8, 2008 at 5:05 pm