Acetic Acid → [1-(4-Chloro-3-ethoxy-benzyl)-piperidin-4-yl]-carbamic acid tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

A mixture of piperidin-4-yl-carbamic acid tert-butyl ester (5.0 g, 25.0 mmol, 1.0 equiv; commercially available), 4-chloro-3-ethoxy-benzaldehyde (5.54 g, 30.0 mmol, 1.2 equiv; intermediate E2, vide infra) and acetic acid (5.7 mL, 6.01 g, 100.0 mmol, 4.0 equiv) in ethanol (25 mL) was heated by microwave irradiation to 100° C. for 5 min. Sodium cyanoborohydride (3.14 g, 50.0 mmol, 2.0 equiv), dissolved in ethanol (10 mL), was added and the reaction mixture heated by microwave irradiation to 100° C. for an additional time period of 10 min. The solvent was removed under reduced pressure and the crude reaction product extracted from a solution of 1 M NaOH (100 mL) with ethyl acetate (3×100 mL). The combined organic phases were dried over MgSO4, concentrated by evaporation under reduced pressure and the crude material purified by silica column chromatography using a MPLC system (CombiFlash Companion, Isco Inc.) eluting with a gradient of heptane/ethyl acetate providing 3.91 g (42%) of the title compound. MS (ISP): 369.0 [M+H]+.

Provenance & Evidence