Ethyl isocyanate → (rac)-4-(4-Cyanophenyl)-5,6,7,8-tetrahydroisoquinolin-8-yl ethylcarbamate

Participants

Reaction Steps

A cooled (0° C.) solution of (rac)-4-(8-hydroxy-5,6,7,8-tetrahydroisoquinolin-4-yl)benzonitrile (example 11) (50 mg, 200 μmol) in CH2Cl2 (1.4 mL) was treated with ethyl isocyanate (24.8 μL, 300 μmol) and Et3N (24.8 μL, 300 μmol). After stirring 1 night at room temperature and 1 h at reflux again ethyl isocyanate (24.8 μL, 300 μmol) and Et3N (24.8 μL, 300 μmol) were added. The solution was refluxed for 9 h, treated again with ethyl isocyanate (24.8 μL, 300 μmol), Et3N (24.8 μL, 300 μmol) and DMAP (2.4 mg, 20 μmol). After 1 night at room temperature MeOH (2 mL) was added. The reaction mixture was poured on aq. sat. NaHCO3 solution followed by extraction with AcOEt (3×). The organic phases were washed once with aq. sat. NaCl solution. The combined organic phases were dried (Na2SO4), filtered and purified by flash chromatography (50 g SiO2, Telos-cartridge, CH2Cl2/MeOH 1%). Precipitation from CH2Cl2 with n-pentane gave the title compound (33 mg, 51%) as off-white foam. MS: 322.2 (M+H+).

Provenance & Evidence