Hydrochloric Acid → HCID 66936525, compound

Participants

Reaction Steps

A mixture of methyl N-{(1S)-2-[bis(phenylmethyl)amino]-1-methylethyl}-L-alaninate (J. Org. Chem. 1995, 60, 4177-4183) (2.156 g, 6.33 mmol), concentrated hydrochloric acid 37% (0.805 mL), 5% palladium on carbon (0.863 g), and EtOH (40 mL) was hydrogenated under a hydrogen balloon for 48 h. The mixture was filtered through Celite, and the solids were washed with MeOH and CH2Cl2. The filtrates were combined and concentrated under reduced pressure. The residue was redissolved in EtOH (55 mL), p-toluenesulfonic acid (0.344 g) was added, and the mixture was heated at reflux for 16 h. The mixture was concentrated under reduced pressure and partitioned between CH2Cl2 and NaHCO3. The aqueous layer was back extracted with CH2Cl2, and the combined organic layers were dried (MgSO4), filtered, and concentrated under reduced pressure. The residue was purified by flash chromatography (9:1, CH2Cl2:MeOH) to provide methyl N-{(1S)-1-methyl-2-[(phenylmethyl)amino]ethyl}-L-alaninate (685 mg, 50%). LCMS: (M+H)+: 129.1. The leftover aqueous layer was extracted further with 40% isopropanol in CHCl3 twice, and the combined organic layers were dried (Na2SO4), filtered, and concentrated to yield (3S,5S)-3,5-dimethyl-2-piperazinone (306 mg, 38%). LCMS: (M+H)+: 129.1.

Provenance & Evidence