Reaction Steps
To a solution of the product of Example 175A (0.025 mmol) in dichloromethane (1.0 mL) was added trifluoroacetic acid (1.0 mL), and the mixture was stirred at room temperature for 1 hour. The solvent was evaporated, and the reaction mixture was partitioned between ethyl acetate and dilute NaHCO3 solution. The organic layer was washed with brine, dried over MgSO4, filtered and concentrated. The residue was dissolved in tetrahydrofuran (0.25 mL) and diisopropylethylamine (0.015 mL, 0.086 mmol) and methyl chloroformate (0.002 mL, 0.026 mmol) were added at room temperature. After 2 hours water was added and the reaction was extracted with ethyl acetate. The organic layer was washed with brine, dried over MgSO4, filtered and concentrated. The residue was chromatographed on silica gel eluting with a gradient starting with dichloromethane and ending with ethyl acetate to give the title compound (0.006 g, 34% yield). 1H NMR (300 MHz, DMSO-d6), δ ppm 0.76 (2s, 6 H), 0.79 (s, 9 H), 1.45-1.56 (m, 2 H), 2.71-2.80 (m, 3 H), 3.08 (dd, J=5.4, 10.9 Hz, 1 H), 3.18 (dd, J=5.4, 10.9 Hz, 1 H), 3.49 (s, 3 H), 3.55 (s, 3 H), 3.59-3.67 (m, 1 H), 3.81 (d, J=9.6 Hz, 1 H), 4.02 (d, J=9.2 Hz, 1 H), 4.04-4.21 (m, 2 H), 4.62 (m, 1 H), 4.90 (d, J=5.5 Hz, 1 H), 6.61 (d, J=9.6 Hz, 1 H), 6.92 (d, J=9.2 Hz, 1 H), 7.10-7.21 (m, 7 H), 7.29-7.31 (m, 1 H), 7.47 (d, J=8.8 Hz, 1 H), 7.78 (d, J=8.8 Hz, 1 H), 7.82-7.89 (m, 4 H), 8.64 (m, 1 H).
