To a mixture of 45 mg (0.2 mmol) of 1-chloro-4-hydroxy-isoquinoline-3-carboxylic acid, 76 mg (0.2 mmol) of benzotriazol-1-yl-(bis-dimethylamino-methylene)-oxonium hexafluoro phosphate (HBTU), 32 μl (2-amino-ethyl)-carbamic acid tert-butyl ester (0.2 mmol), and 1 ml of dichloromethane was added 96 μl (0.55 mmol) of ethyl-diisopropyl-amine with stirring. Stirring was continued at ambient temperature for 5 days. The product was isolated from the reaction mixture by flash column chromatography on silica gel using hexanes:ethyl acetate (8:2) as the eluent to give a tan gum. 8 mg of the title compound were obtained; MS-(−)-ion: M−1=364.0.
