Triphenylphosphine (0.0.612 g) was added to a cooled (−78° C.) solution of hexachloroacetone (0.18 ml) and N-t-butyloxycarbonyl-2-methylalanine (0.441 g) in dry DCM (15 ml) under argon. The resulting mixture was stirred at low temperature for 20 minutes. Then 2-chloro-4-(phenylsulphanyl)aniline (0.5 g) (Method 5) and dry triethylamine (0.33 ml) were added. The resulting mixture was slowly warmed to room temperature, under argon, before being stirred for 1 hour at room temperature. Saturated aqueous ammonium chloride solution (15 ml) was added and the mixture was extracted with DCM (2×50 ml). The organic extracts were combined, washed with brine and dried. Volatile material was removed by evaporation and the residue was purified by chromatography on a silica gel column eluting with 2% ethyl acetate/DCM to give the title compound. NMR (CDCl3): 1.40-1.45 (m, 12H), 4.294.40 (m, 1H), 4.864.95 (m, 1H), 7.20-7.40 (m, 7H), 8.30-8.38 (m, 1H), 8.64 (brs, 1H); MS (ESP−): 405.
