(S)-3-(tert-Butoxycarbonyl(isopropyl)amino)-2-(4-chlorophenyl)propanoic acid (59 mg, 0.17 mmol, see Example H), N1-((ethylimino)methylene)-N3,N3-dimethylpropane-1,3-diamine hydrochloride (44 mg, 0.23 mmol), HOBt-H2O (35 mg, 0.23 mmol) and triethylamine (12 mg, 0.12 mmol) were added to 5-isopropoxy-4-(piperazin-1-yl)-1H-pyrrolo[2,3-b]pyridine (30 mg, 0.12 mmol) in DCM (10 mL). The reaction was stirred at room temperature for 18 hours. The reaction was then diluted with DCM (50 mL) and washed with 1N HCL, 10% K2CO3 and brine. After drying over MgSO4, the residue was concentrated to dryness and purified by chromatography (SP4, 12+M, water/ACN 90/10→0/100, 20 CV) to yield (S)-tert-butyl 2-(4-chlorophenyl)-3-(4-(5-isopropoxy-1H-pyrrolo[2,3-b]pyri din-4-yl)piperazin-1-yl)-3-oxopropyl(isopropyl)carbamate (42 mg, 62% yield) as a solid.
