Triethylamine → di-tert-butyl (2S)-2-(4-cyanophenyl)piperazine-1,4-dicarboxylate

Participants

Reaction Conditions

Reaction Steps

1-Chloroethyl chloroformate (2.7 g, 18.9 mmol) was added to a solution of 4-((2S)-1,4-dibenzylpiperazin-2-yl)benzonitrile (1.4 g, 3.81 mmol) in dichloroethane (30 ml). The reaction mixture was vigorously stirred at room temperature for 10 hours. The solvent was evaporated under reduced pressure and methanol (40 ml) was added to the residue. The mixture was heated at 80° C. for one hour and the solvent was evaporated under reduced pressure to afford (2S)-2-(4-cyanophenyl)piperazine as white crystals. Di-tert-butyl di-carbonate (1.9 g, 8.71 mmol) was added to a solution of triethylamine (1.2 g, 11.9 mmol) and (2S)-2-(4-cyanophenyl)piperazine in tetrahydrofuran (50 ml) at room temperature and the mixture was stirred at 50° C. for one hour. The mixture was partitioned between water and ethyl acetate. The organic layer was washed with brine, dried over magnesium sulfate and concentrated in vacuo. The residue was purified by silica gel column chromatography eluting 10-20% ethyl acetate in hexane to furnish di-tert-butyl

Provenance & Evidence