Reaction Steps
To a solution of compound 9 (1.30 g, 2.50 mmol) and 1H-tetrazole (3% wt, 10.0 mmol) in DCM (30 mL) was added N,N-diethyl-1,5-dihydro-3H-2,4,3-benzodioxaphosphepin-3-amine (1.20 g, 1.05 mmol). After the reaction mixture was stirred at room temperature for 15 min, it was cooled (−20° C.), stirred for another 10 min and then mCPBA (3.40 g, 50-55% wt, 10.0 mmol) was added. The reaction mixture was stirred at −20° C. for 20 min, and then quenched by the addition of saturated aqueous NaHCO3 (40 mL) and diluted with DCM (30 mL). The organic phase was washed with saturated aqueous NaHCO3 (2×60 mL) and brine (2×40 mL), dried (MgSO4) and filtered. Next, the filtrate was concentrated in vacuo. The residue was purified by silica gel column chromatography (hexane/ethyl acetate, 5/1-3/1, v/v) to give 10 as a pale yellow oil (1.48 g, 89%). Rf=0.40 (hexane/ethyl acetate, 1/1, v/v). [α]25D=−10.3° (c=1.0, CHCl3). 1H NMR (300 MHz, CDCl3): δ 7.35-7.15 (m, 9H, aromatic), 5.98-5.85 (m, 1H, OCH2CH═CH2), 5.65 (d, 1H, J=1.2 Hz, J=17.4 Hz, OCH2CH═CH2), 5.50 (d, 1H, J=1.2 Hz, J=10.5 Hz, OCH2CH═CH2), 5.18-5.01 (m, 4H, C6H4(CH2O)P), 3.81 (dd, 1H, J2,3=10.5 Hz, J3,4=9.3 Hz, H-3), 4.64-4.52 (m, 6H, H-1, H-4, OCH2CH═CH2, CH2Ph), 3.82 (d, 1H, J6a,6b=9.0 Hz, H-6a), 3.72-3.61 (m, 2H, H-5, H-6b), 3.41 (dd, 1H, J1,2=7.4 Hz, J2,3=10.5 Hz, H-2), 0.92 (s, 9H, SiC(CH3)3), 0.16 (s, 3H, Si(CH3)), 0.15 (s, 3H, Si(CH3)). 13C NMR (75 MHz, CDCl3): δ 154.38 (C═O), 138.02-127.56 (aromatic), 131.33 (OCH2CH═CH2), 118.99 (OCH2CH═CH2), 97.13 (C-1), 76.77 (C-3), 74.27 (C-4), 74.08 (C-5), 73.50 (CH2Ph), 69.06 (OCH2CH═CH2), 68.74 (C-6), 68.55 (OC6H4(CH2O)P), 68.50 (OC6H4(CH2O)P), 65.97 (C-2), 25.53 (SiC(CH3)3), 17.92 (SiC(CH3)3), −4.35 (Si(CH3)2), −5.28 (Si(CH3)2). HR MS (m/z) calculated for C31H42N3O10PSi[M+Na]+, 698.2275. found, 698.2315.
