Triethylamine → (S)-2-Benzyl-4-(3-cyclopentyloxy-4-methoxy-phenyl)-piperazine-1-carboxylic acid ethyl ester

Participants

Reaction Steps

A solution of (S)-3-Benzyl-1-(3-cyclopentyloxy-4-methoxy-phenyl)-piperazine (Example 2) (73 mg, 0.2 mmol) in THF (0.5 mL) at room temperature was treated with triethylamine (28 μL, 0.2 mmol) followed by ethyl chloroformate (19 μL, 0.2 mmol). The reaction mixture was stirred for 2 h then diluted with EtOAc (2 mL) followed by a saturated aqueous NaHCO3 solution (1 mL). The organic phase was isolated and further washed with an additional portion of a saturated aqueous NaHCO3 solution (1 mL) followed by a brine solution (1 mL). The organic component was dried over MgSO4, filtered, and evaporated to an oil which was purified by silica gel flash chromatography with 10% then 30% EtOAc/hexane as eluant to afford product as an oil (30 mg, 34%). 1H NMR (CDCl3) 1.25 (t, J=7.2, 3H), 1.60-1.65 (m, 2H), 1.79-1.89 (m, 3H), 1.92-2.00 (m, 2H), 2.60-2.72 (m, 2H), 2.95 (dd, J=12.9, 4.8, 1H), 3.20-3.28 (m, 2H), 3.33-3.42 (m, 2H), 3.79 (s, 3H), 4.08-4.13 (m, 3H), 4.40 (br s, 1H), 4.69-4.72 (m, 1H), 6.39 (dd, J=8.6, 2.4, 1H), 6.47 (s, 1H), 6.77 (d, J=8.6, 1H), 7.22-7.34 (m, 5H). LC/MS 7.81 min, [M+1]+ 439.

Provenance & Evidence