Reaction Steps
To a stirring solution of alcohol 22 (104 mg, 0.111 mmol, 1.0 equiv) in CH2Cl2 (1.1 mL), in a 10 mL rb flask at 0° C., was added diisopropylethylamine (135 μL, 0.775 mmol, 7.0 equiv) and DMSO (80 μL, 1.11 mmol, 10.0 equiv). The solution stirred at 0° C. for 5 min and SO3.Py (71 mg, 0.444 mmol, 4.0 equiv) was added in one portion. Stirring continued at 0° C. for 1.25 h, after which the reaction mixture was quenched by addition of saturated aqueous NaHCO3 solution (2 mL). The mixture stirred at room temperature for 10 min until effervescence was complete, and the phases were separated. The aqueous phase was extracted three times with CH2Cl2 (10 mL), and the combined organic phases were dried over Na2SO4, filtered, and concentrated under reduced pressure. The resulting residue was washed through a small plug of silica gel with 40% EtOAc/hexanes (100 mL), and the solvent was removed under reduced pressure to provide pure aldehyde 23 (96.4 mg, 93%) as a clear viscous oil: Rf=0.44 (30% EtOAc/hexanes); [α]D20=+4.8 (c=0.82, CHCl3); 500 MHz 1H NMR (CDCl3) δ 9.79 (t, J=2.4 Hz, 1H), 7.38-7.28 (m, 5H), 7.24 (d, J=8.8 Hz, 2H), 6.88 (d, J=8.8 Hz, 2H), 6.04 (d, J=15.6 Hz, 1H), 5.47 (dd, J=16.1, 6.3 Hz, 1H), 4.81 (d, J=6.8 Hz, 1H), 4.78 (d, J=6.8 Hz, 1H), 4.75-4.71 (m, 2H), 4.68 (s, 1H), 4.62 (s, 2H), 4.60 (s, 1H), 4.51 (d, J=10.7 Hz, 1H), 4.46 (d, J=10.7 Hz, 1H), 4.19 (m, 1H), 4.13-4.09 (m, 1H), 4.07 (ddd, J=9.0, 4.1, 2.4 Hz, 1H), 3.85-3.75 (m, 2H), 3.80 (s, 3H), 3.56-3.42 (m, 3H), 3.29 (s, 3H), 2.67-2.63 (m, 2H), 2.44 (dd, J=8.3, 6.3 Hz, 2H), 2.28-2.15 (m, 4H), 2.05-1.90 (m, 8H), 1.80 (ddd, J=14.2, 8.8, 2.4 Hz, 1H), 1.67 (ddd, J=14.2, 10.0, 4.2 Hz, 1H), 1.59 (ddd, J=13.8, 7.0, 5.3 Hz, 1H), 1.53 (ddd, J=13.7, 9.3, 3.9 Hz, 1H), 1.16 (d, J=6.3 Hz, 3H), 1.13 (s, 3H), 1.09 (s, 3H), 0.88 (s, 9H), 0.08 (s, 3H), 0.08 (s, 3H); 125 MHz 13C NMR (CDCl3) δ 207.5, 201.6, 159.5, 144.4, 144.3, 138.0, 137.2, 130.4, 129.6, 129.2, 128.6, 128.0, 127.9, 114.1, 109.1, 109.0, 104.0, 93.4, 79.3, 75.2, 75.1, 75.0, 75.0, 72.1, 71.6, 70.8, 69.9, 69.6, 55.5, 52.7, 49.4, 44.4, 42.9, 42.3, 41.3, 41.2, 40.9, 40.5, 38.2, 37.7, 30.6, 26.1, 23.1, 22.1, 18.3, 14.0, −3.8, −4.4; 125 MHz DEPT 13C NMR (CDCl3) CH3 δ 55.5, 52.7, 26.1, 23.1, 22.1, 14.0, −3.8, −4.4; CH2 δ 109.1, 109.0, 93.4, 72.2, 69.6, 49.4, 42.9, 42.4, 41.3, 41.2, 40.9, 40.5, 38.2, 37.7, 30.7; CH δ 201.7, 137.2, 129.6, 129.2, 128.6, 128.0, 127.9, 114.1, 79.3, 75.2, 75.1, 75.0, 71.6, 70.8, 69.9; CH0 δ 207.5, 159.5, 144.4, 144.3, 138.0, 130.4, 104.0, 44.4, 18.3; IR (neat) 2936, 2857, 1725, 1652, 1613, 1514, 1463, 1381, 1250, 1174, 1112, 1041, 892, 836 cm−1.
