88 mg of 4-[4-((2S)-2-benzenesulfonylamino-2-tert-butoxycarbonyl-ethyl)-phenoxy]-butyric acid were dissolved in tetrahydrofuran and 22.6 mg of 1,4,5,6-tetrahydropyrimidin-2-ylamine, 123 mg of diisopropylethylamine and 79.4 mg of HATU were added. The reaction mixture was stirred overnight, and the solvent was removed in vacuo. The residue was dissolved in dichloromethane and washed with saturated aqueous sodium bicarbonate solution and saturated aqueous sodium chloride solution. The organic phase was dried with sodium sulfate, filtered and the solvent was removed in vacuo. The residue was chromatographed on reversed-phase (C-1 8) silica gel eluting with a gradient of 10-90% acetonitrile in water. Yield 40.1 mg. MS (FAB+): m/e=545.3 (M+H)+.
