A mixture of ((1S,2S)-1-{[[(1R,2R)-2-(5-fluoro-pyridin-2-yl)-cyclopropanecarbonyl]-(4-hydroxy-phenyl)-amino]-methyl}-2-methyl-butyl)-carbamic acid tert-butyl ester (51 mg, 0.11 mmol), K2CO3 (69 mg, 0.5 mmol) and cyclobutylmethyl bromide (22 mg, 0.15 mmol) in DMF was stirred at 55° C. for over night. After cool to rt, the mixture was filtered through a silica pad (EtOAc). The filtrate was concentrated and the residue was subjected to ISCO (12 g column, 0-40% EtOAc in hexane over 25 min) to give the titled compound (53 mg). MS (MH+ 540).
