Reaction Steps
To a solution of 15 (3.5 g, 10.4 mmol) in dichloromethane (20 mL) was charged DMF (0.04 mL, 0.5 mmol). This solution was cooled under an ice bath. Thionyl chloride (0.85 mL, 11.5 mmol) was then added under 5° C., and the resulting reaction was aged for 3 h at this temperature. Once the reaction was complete, 5% aqueous NaCl (16.5 mL) was added. The organic layer was separated and washed with 5% aqueous NaCl (16.5 mL). The solvent was removed via rotovap, and the crude was purified by silica gel column chromatography (0 to 10% AcOEt/hexane) to give the desired compound 16 as an oil (3.05 g, 74%). 1H NMR (CDCl3, 500 MHz): δ 8.20 (dd, J=5.1, 1.7 Hz, 1H), 7.58 (d, J=8.1 Hz, 1H), 7.51 (dd, J=8.1, 1.1 Hz, 1H), 7.18 (s, 1H), 7.12 (dd, J=6.3, 2.7 Hz, 1H), 6.88 (dd, J=7.3, 5.1 Hz, 1H), 4.77 (ABq, J=12.9 Hz, 2H), 3.72 (m, 1H), 3.46 (dd, J=14.2, 4.4, 1H), 3.18 (dd, J=14.2, 8.7 Hz, 1H), 1.67 (s, 9H); 13C NMR (CDCl3, 125 MHz): δ 177.6, 159.1, 146.5, 143.3, 136.6, 131.0, 129.7 (m, 2C), 124.0, 123.0, 123.9 (q, J=271 Hz), 117.4, 126.6, 62.4, 58.8, 46.1, 32.9, 28.6.
