To a solution of the product from Example 1C (0.318 g, 1.081 mmol) in dichloromethane (8 mL) was added pyridine (0.256 g, 3.24 mmol). 3,3-Dimethylbutanoyl chloride (0.160 g, 1.189 mmol) was slowly added and the resulting reaction mixture was stirred at room temperature for 3 hours. The reaction mixture was concentrated and the residue was purified by preparative HPLC on a Phenomenex Luna C8(2) 5 um 100 Å AXIA column (30 mm×75 mm). A gradient of acetonitrile (A) and 0.1% trifluoroacetic acid in water (B) was used, at a flow rate of 50 mL/min (0-0.5 min 10% A, 0.5-6.0 min linear gradient 10-100% A, 6.0-7.0 min 100% A, 7.0-8.0 min linear gradient 100-10% A) to yield the title compound (0.38 g, 88%). 1H NMR (400 MHz, CD3Cl) δ ppm 1.11 (s, 6H) 2.33 (s, 2H) 6.86 (dd, J=6.94, 4.12 Hz, 1H) 7.30-7.42 (m, 3H) 7.63-7.79 (m, 2H) 8.51 (dd, J=4.12, 1.73 Hz, 1H) 8.68 (dd, J=6.94, 1.63 Hz, 1H). MS ESI(+) m/z 393.4 [M+H]+.
