0.5M Potassium bis-(trimethylsilyl)-amide in toluene (10 ml) was added dropwise at −30° C. in an argon atmosphere to a stirred solution of 2-oxo-1,2,3,4-tetrahydroquinoline (735 mg) in tetrahydrofuran (50 ml). After further cooling to −50° C. a solution of N-(tert-butoxycarbonyl)-6-bromo-hexylamine (1.5 g) in tetrahydrofuran (10 ml) was added slowly. Subsequently the temperature was allowed to raise to room temperature followed by heating at 50-60° C. for 48 hours. Ice and water were added and the mixture was extracted twice with ethyl acetate. The organic phases were washed with saturated sodium chloride, dried and evaporated to leave a yellow oil which after purification by chromatography on silica gel with ethyl acetate/hexane (1:1) as eluent gave the desired compound as a colourless oil.
