Reaction Steps
A solution of 27 (0.9 g, 2.2 mmol) in DCM (20 mL) was cooled to 0° C. and treated with DIPEA (0.75 mL, 4.3 mmol) and DMAP (31 mg, 0.25 mmol). Methanesulfonyl chloride (0.3 mL, 3.9 mmol) was then added. After 1.5 h, the solution was diluted with DCM, washed successively with 1M HCl, brine, dried over anhydrous Na2SO4, filtered and concentrated to afford sulfonamide 28 as an off-white foam (1.1 g) which was used without further purification. 1H NMR (CDCl3, 300 MHz): δ5.23 (d, J=9.0 Hz, 1H), 4.74 (d, J=5.1 Hz, 1H), 4.31-4.28 (m, 2H), 4.03 (app t, J=9.3 Hz, 1H), 3.83-3.76 (m, 1H), 3.76 (s, 3H), 3.59-3.47 (m, 2H), 3.42-3.4 (m, 1H), 2.91 (s, 3H), 2.51 (dd, J=5.7, 13.8 Hz, 1H), 2.09-2.05 (m, 1H), 1.75-1.53 (m, 6H), 1.43 (s, 9H), 1.26-1.04 (m, 6H) ppm; 13C NMR (CDCl3, 75 MHz): δ172.7, 171.6, 155.9, 79.8, 66.1, 63.1, 56.9, 52.8, 50.7, 47.2, 46.2, 41.2, 35.6, 33.3, 29.8, 28.5, 28.4, 26.2, 26.1, 26.0 ppm.
