p-Aminoacetophenone → tert-Butyl N-{2-{(4-acetylphenyl)amino}-2-oxoethyl}-N-(phenylmethyl)carbamate

Participants

Reaction Steps

Isobutyl chloroformate (35.1 g, 0.26 mol) was added (15 min) to an ice-cold solution of tert-butyl N-(2-hydroxy-2-oxoethyl)-N-(phenylmethyl)carbamate (65.0 g, 0.24 mol), described in preceding section a), and Et3N (31.0 g, 0.31 mol) in CH2Cl2 (610 mL). The mixture was stirred at 0° for 45 min. Solid 4′-aminoacetophenone (34.8 g, 0.26 mol) was added portion wise to the reaction mixture. The reaction mixture was stirred at 0° for 1.5 h and then at room temperature for 16 h. H2O (10 mL) was added. The resulting solution was concentrated under reduced pressure. The residue was dissolved in EtOAc (1 L). The solution was washed successively with 1 N aqueous HCl (2×300 mL), a saturated aqueous solution of NaHCO3 (2×300 mL) and brine (200 mL), dried (MgSO4) and concentrated under reduced pressure. The resulting brownish solid was crystallized (EtOAc: Hex) to give the title compound (56.8 g, 61% yield) as a white solid: 1H NMR (400 MHz, CDCl3) δ9.72 (broad s, 1H), 7.90 (d, J=8.6 Hz, 2H), 7.40-7.54 (m, 2H), 7.26-7.39 (m, 5H), 4.55 (s, 2H), 3.96 (s, 2H), 2.56 (s, 3H), 1.51 (s, 9H); MS (FAB) m/z383 (MH)+.

Provenance & Evidence