A solution of N-[(1-phenylindole-2-carbonyl)valinyl]-3-amino-4-oxo-5-fluoropentanoic acid, t-butyl ester (154 mg) in anisole (0.2 mL) and methylene chloride (2 mL) was treated with TFA (1 mL), and the resultant reaction mixture was stirred for one hour under a nitrogen atmosphere at room temperature. The reaction mixture was concentrated and chased with methylene chloride, then triturated with ether to yield the title product as a white powder (100 mg). TLC: (methylene chloride/methanol/acetic acid, 20:1:1): Rf=0.38, MS (EI) for C25H26FN3O5: MH+=468; (M−H)−=466.
