Diisopropylethylamine → {(R)-1-[(S)-2-Benzyl-4-(3-cyclopentyloxy-4-methoxy-phenyl)-piperazine-1-carbonyl]-2-hydroxy-2-methyl-propyl}-carbamic acid tert-butyl ester

Participants

Reaction Steps

A solution of (S)-3-Benzyl-1-(3-cyclopentyloxy-4-methoxy-phenyl)-piperazine (92 mg, 0.25 mmol) in CH2Cl2 (1 mL) and DMF (500 μL) at 0-5° C. was treated with diisopropylethylamine (87 μL, 0.50 mmol), (R)-2-(tert-butoxycarbonylamino)-3-hydroxy-3-methylbutanoic acid (64 mg, 0.28 mmol), followed by HATU (105 mg, 0.28). The reaction mixture was allowed to warm to room temperature and stir for 3 h. After this time the reaction mixture was evaporated and the residue purified by silica gel flash chromatography with 30% then 40% EtOAc/hexanes as eluant to afford the intermediate {(R)-1-[(S)-2-Benzyl-4-(3-cyclopentyloxy-4-methoxy-phenyl)-piperazine-1-carbonyl]-2-hydroxy-2-methyl-propyl}-carbamic acid tert-butyl ester as an oil (100 mg, 69%). LC/MS (Method B) 4.36 min, [M+1]+ 582.

Provenance & Evidence