Reaction Steps
The procedure for 10 was used with the aldehyde from 21 (17.5 g, 31.6 mmol), Py.SO3 (15.2 g, 95.5 mmol) and Et3N (13.3 mL, 95.5 mmol), NaH (0.90 g, 39.7 mmol) and triethylphosphonoacetate (7.2 mL, 40.3 mmol) to yield 8.96 g (63% for 3 steps) of the ester 22 by flash column chromatography (EtOAc/Hexane 1:9) as a colorless oil: IR (CHCl3) 2957, 2931, 2856, 1720, 1651, 1613, 1513, 1463, 1366, 1250, 1180, 1093, 1077, 837 cm−1; 1H NMR (300 MHz, CDCl3) ε7.31-7.27 (m, 2H), 7.03 (dd, J=15.8, 7.8 Hz, 1H), 6.93-6.91 (m, 2H), 5.83 (dd, J=15.8, 1.3 Hz, 1H), 4.48b -4.40 (m, 2H), 4.23 (q, J=7.1 Hz, 2H), 3.84 (s, 3H), 3.67 (m, 1H), 3.52 (m, 1H), 3.30 (dd, J=9.1, 7.2 Hz, 1H), 2.59 (m, 1H), 2.00 (m, 1H), 1.33 (t, J=7.1 Hz, 3H), 1.09 (d, J=6.8 Hz, 3H), 1.01 (d, J=7.0 Hz, 3H), 0.94 (s, 9H), 0.08 (m, 6H); 13C NMR (75 MHz, CDCl3) δ 166.5, 159.0, 152.7, 130.6, 129.0, 120.4, 113.6, 76.8, 72.5, 71.8, 60.0, 55.1, 40.2, 38.0, 26.0, 18.2, 14.8, 14.3, 14.2, −4.0, −4.2; LRMS (ESI) 473.2 [M+Na]+; HRMS (ESI) calcd for C25H42O5SiNa 473.2699 [M+Na]+, found 473.2716; [α]20D−28.3 (c 0.41, CHCl3).
