Reaction Steps
A solution of 9-BBN (0.5 M, 32.5 mL, 16.3 mmol) in THF was added to a stirred solution of alkene 137 (4.02 g, 10.8 mmol) in THF (50 mL) at 20° C. under N2 and the mixture was stirred at 20° C. for 30 min. The mixture was cooled to 0° C., a solution of sodium acetate (3 M, 25 mL, 75 mmol) and then H2O2 (70%, 25 mL, 468 mmol) were added carefully and stirred for 10 min. MeOH (100 mL) was added and the mixture stirred at 20° C. for 20 min. The mixture was partitioned between aqueous Na2CO3 solution and EtOAc. The combined organic fraction was dried and the solvent evaporated. The residue was purified by chromatography, using a gradient (50-70%) of EtOAc/pet. ether, to give alcohol 138 (2.08 g, 49%) as a pale yellow solid: mp (EtOAc/pet. ether) 93-94° C.; 1H NMR δ 8.22 (s, 1H, H-9), 7.72 (s, 1H, H-5), 3.79 (br q, J=5.1 Hz, 2H, CH2O), 3.59-3.67 (m, 2H, CH2OSi), 3.12-3.24 (m, 4H, CH2), 2.93-3.03 (m, 2H, CH2), 2.73-2.84 (m, 1H, H-7), 2.30 (br s, 1H, OH), 2.11-2.21 (m, 2H, CH2), 0.87 [s, 9H, SiC(CH3)3], 0.04 [s, 6H, Si(CH3)2]; 13C NMR δ 165.7, 154.2, 148.3, 147.3, 132.3, 122.8, 114.5, 65.4, 62.2, 42.0, 35.8, 35.5, 34.0, 30.6, 25.8 (3), 18.3, −5.41 (2). Anal. calcd for C20H31N3O3S.¼H2O: C, 61.7; H, 8.0; N, 10.8. Found: C, 61.5; H, 7.8; N, 10.9%.
