Reaction Steps
Following the procedure in the preparation of 11, compound 11″ was prepared from alcohol 10″ (1.69 g, 3.40 mmol) as a pale white foamy solid (2.12 g, 96% yield): [α]26D=+14.1 (c=1.01, MeOH); HPLC of 11″ for purity: 97.7%, [major peak: Rt=23.7 min; minor peak: 16.2 min; column: Chiralcel ODH (250×4.6 mm), UV detector, 210 nm, 5% 2-propanol in hexanes; flow rate: 1.0 mL/min]. 1H NMR (200 MHz, CDCl3) δ 7.75 (d, 2H, J=8.4 Hz), 7.25 (d, 2H, J=8.4 Hz), 6.91 (br s, 1H), 6.14 (s, 2H), 5.12 (br s, 1H), 4.94 (t, 1H, J=6.0 Hz), 4.52 (dd, 1H, J1=14.0 Hz, J2=6.0 Hz), 4.30 (dd, 1H,//=14.4 Hz, J2=5.2 Hz), 4.18 (br s, 1H), 3.84 (s, 3H), 3.82 (s, 6H), 2.42 (s, 3H), 2.32-2.22 (m, 2H), 1.45 (s, 9H), 1.43 (s, 9H). 13C NMR (50 MHz, CDCl3) δ 170.7, 167.1, 161.2, 159.5, 155.5, 145.5, 133.1, 130.1, 128.2, 106.3, 90.9, 82.4, 79.9, 56.0, 55.6, 50.8, 35.0, 32.7, 28.5, 28.1, 21.8. HRMS calcd for C31H45N2O11S (M+H)+: 653.2744. found: 653.2729.
