反应详情

To a solution of Intermediate 54b (0.73 g, assumed 1.70 mmol) in ethyl acetate (8 mL) was added 1N sodium hydroxide solution (4.5 mL, 4.50 mmol). Stirred for 5 min then 2,2,2-trichloroethyl chloroformate (275 μL, 2.00 mmol) was added and the mixture stirred vigorously at RT for 3.5 h. Diluted with EtOAc, washed with water and brine, dried, and concentrated in vacuo. The residue was purified by FCC, using 0-15% EtOAc in cyclohexane, to give the still impure title compound (1.01 g). 1H NMR (300 MHz, CDCl3): inter alia 1.02-1.15 (18H, m), 1.18-1.38 (12H, m), 2.34 (3H, s), 4.82 (2H, s), 6.43 (1H, s), 6.69-6.77 (2H, m), 6.84-6.96 (2H, m).

1. stirringthe mixture stirred vigorously at RT for 3.5 h
2. washwashed with water and brine
3. customdried
4. concentrationconcentrated in vacuo
5. customThe residue was purified by FCC