Potassium Carbonate → 6-cyclopentyloxy-7-methoxy-1-(3-methoxy-benzyl)-1H-isoquinoline-2-carboxylic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of 6-hydroxy-7-methoxy-1-(3-methoxy-benzyl)-1H-isoquinoline-2-carboxylic acid ethyl ester (890 mg, 2.41 mmol) in anhydrous N,N-dimethylformamide (25 mL) was added potassium carbonate (2.0 g, 14.5 mmol) and cyclopentyl iodide (0.84 mL, 7.24 mmol) dropwise. The reaction mixture was heated with stirring at 85° C. for 18 h. The solvent was evaporated and the residue was diluted with ethyl acetate (50 mL) and water (50 mL). The aqueous phase was extracted with ethyl acetate (3×50 mL). The combined extracts were washed with saturated aqueous sodium chloride solution (50 mL), dried over anhydrous magnesium sulfate, filtered and concentrated in vacuo. Flash chromatography (Merck Silica gel 60, 70–230 mesh, 20% ethyl acetate/hexane) afforded 6-cyclopentyloxy-7-methoxy-1-(3-methoxy-benzyl)-1H-isoquinoline-2-carboxylic acid ethyl ester (350 mg, 32% yield) as a colorless oil.

Provenance & Evidence