Acetic Acid → [1-(3,5-Diisopropoxy-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 (4.0 g, 20.0 mmol, 1.0 equiv), 3,5-diisopropoxy-benzaldehyde (5.33 g, 24.0 mmol, 1.2 equiv; intermediate D7, vide infra) and acetic acid (4.6 mL, 4.80 g, 80.0 mmol, 4.0 equiv) in ethanol (16 mL) was heated by microwave irradiation to 100° C. for 5 min. Sodium cyanoborohydride (2.51 g, 40.0 mmol, 2.0 equiv), dissolved in ethanol (8 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 on a Isolute flash NH2 chromatography column using a MPLC system (CombiFlash Companion, Isco Inc.) eluting with a gradient of heptane/ethyl acetate providing 3.23 g (40%) of the title compound. MS (ISP): 407.4 [M+H]+.

Provenance & Evidence