# Synthesis of (s)-cathinone from N-acetyl-L-alanine



## William Dampier (Sep 20, 2021)

*(S)-cathinone acetamide var. 1.



*

1. To a stirred suspension of 1000 g N-acetyl-L-alanine(1000 g 5.4 mmol) in dry 2000 ml CH2Cl 2 (x2000 mL), cooled to 0°C in an ice-water bath, was added 2000 g oxalyl chloride followed by small portion of pyridine.
2. The reaction mixture was allowed to warm gradually to room temperature and was then stirred further for 5 h. The solvent and excess oxalyl chloride were removed by rotary evaporation at 35 °C to afford the crude acid chloride.
3. To this chloride was then added with stirring a solution of the 600 g benzene in 500 ml CH2Cl2, followed by 1017 g AlCl3 and the resulting mixture was allowed to react for 18 h.
4. The reaction mixture was then cooled in an ice-water bath and slowly quenched with 1 N HCl and CH2Cl2.
5. The aqueous layer was extracted with 300 ml CH2Cl2 and the organic layers were combined, dried over Na2SO4, and rotary evaporated to give the crude product, which was crystallized in hexane.
6. In this way, the following (S)-cathinone acetamide were prepared. Yield: 800 g.


*(S)-cathinone acetamide var.2.


*

1. In the reactor, equipped with a stirrer, a thermometer, reflux condenser and a drip funnel, add 780 g POCl3.
2. In the drip funnel poured 1000 g N-acetyl-L-alanine and 400 ml dimethylformamide.
3. The reaction mass is heated to 100 *С. Within 30 minutes, the mixture was added from a drip funnel.
4. Then the reflux condenser was changed to straight condenser and distill the forming N-acetyl-L-alanine acid chloride.
5. The resulting propionic acid chloride is distilled at atmospheric pressure at a temperature of 80 *С. 1100 g N-acetyl-L-alanine acid chloranhydride was obtained.
6. In three-necked flask, equipped with a reflux condenser, a calcium chloride drying tube, drip funnel and mechanical stirrer, place 982 g aluminum chloride and 2000 ml benzene.
7. Start stirring and was added dropwise 1100 g N-acetyl-L-alanine acid chloride with such speed, to the uniform release of hydrogen chloride.
8. In the case of a rapid reaction, outer cooling is needed. The end of the reaction is determined by the cessation of hydrogen chloride.
9. After completion of the reaction, the reaction mixture was poured onto crushed ice and add a diluted hydrochloric acid solution to dissolve the aluminum hydroxide precipitate.
10. The top, benzene layer separated from the lower, water layer.
11. Benzene solutions are condensed and washed with a dilute solution of sodium hydroxide, water and dried magnesium or sodium sulfate.
12. After the benzene is distilled off, we get (S)-cathinone acetamide prisms, yield: 800g.


*(S)-cathinone hydrochloride.


*

1. The (S)-cathinone acetamide were dissolved in minimal amount of 2-propanol and concentrated HCl was dropwise to pH - 5.
2. The resulting solutions were then stirred at 40 °C for 12 h, put into a freezer and precipitated the hydrochloride salts was crystallization.
3. Filtered on a Buchner funnel and washing with cold acetone to get clear (S)-cathinone hydrochloride, yield: 600 g.


----------



## Jack

William can you tell me if carbamyl groups are labile under friedel crafts conditions because it is known that carbamate esters are reduced to the N alkyl group upon reduction for example the methyl carbamate (S)-methyl (1-phenylpropan-2-yl)carbamate would be reduced to (S) methamphetamine, it would be convient to reduce the ketone to an alkane and the carbamate to the N alkyl derivative.








Reduction of carbamate with LAH


The products of the reduction of esters with $\ce {LiAlH4}$ and the products of the reduction of amides with $\ce {LiAlH4}$ are vastly different. The former reduction cleaves the ester and produces...




chemistry.stackexchange.com


----------



## William Dampier

Ether will not give acylation by Friedel Crafts. Such a protective group is possible only for ready-made amine.


----------



## Jack

https://chemistry.mdma.ch/hiveboard/rhodium/pdf/fc-acylation.n-carbamyl-alpha-amino-acyl-chlorides.pdf


----------

