(S)-3-(tert-Butoxycarbonyl(isopropyl)amino)-2-(4-chlorophenyl)propanoic acid (180 mg, 0.52 mmol, see Example H), N1-((ethylimino)methylene)-N3,N3-dimethylpropane-1,3-diamine hydrochloride (134 mg, 0.70 mmol), HOBt.H2O (108 mg, 0.70 mmol) and triethylamine (106 mg, 1 mmol) were added to 2-methyl-5-(4-(piperazin-1-yl)-1H-pyrrolo[2,3-b]pyridin-5-yl)-1,3,4-oxadiazole (100 mg, 0.36 mmol) in DCM (10 mL). The reaction was stirred at room temperature for 18 hours. After dilution with DCM, the mixture was washed with 1N HCl, 10% K2CO3 and brine. The organic phase was dried over MgSO4 and purified by chromatography (SP4, 12+M, water/ACN 90/10→10/90, 20CV) to yield (S)-tert-butyl 2-(4-chlorophenyl)-3-(4-(5-(5-methyl-1,3,4-oxadiazol-2-yl)-1H-pyrrolo[2,3-b]pyri din-4-yl)piperazin-1-yl)-3-oxopropyl(isopropyl)carbamate (60 mg) as a solid.
