反应详情

Anhydrous triflic anhydride (3.09 mL, 5.19 g, 18.4 mmol, 22 eq) taken from a freshly opened ampule was added rapidly in one portion to a vigorously stirred solution of ketone 12 (0.98 g, 0.84 mmol) and anhydrous pyridine (1.49 mL, 1.46 g, 18.4 mmol, 22 eq) in dry DAM (50 mL) at room temperature under a nitrogen atmosphere. The initial precipitate dissolved gradually and the solution eventually turned a dark red colour. The reaction mixture was allowed to stir for 4.5 h when TLC (80:20 v/v EtOAc/hexane) revealed the complete consumption of the starting material. The mixture was poured into cold saturated NaHCO3 (60 mL) and extracted with DCM (3×80 mL). The combined organic layers were then washed with saturated CuSO4 (2×125 mL), brine (125 mL) and dried (MgSO4). Filtration and evaporation of the solvent afforded the crude product which was purified by flash column chromatography (80:20 v/v hexane/EtOAc) to afford triflate 13 as a light yellow glass (0.74 mg, 61%): [α]25 D=+46.0° (c=0.33, CHCl3); 1H NMR (400 MHz, CDCl3) δ 7.23 (s, 2H, H6), 7.19 (s, 2H, H3), 6.77 (s, 2H, H9), 5.94 (d, 2H, J=8.9 Hz, H11), 5.23 (d, 2H, J=12.0 Hz, Troc CH2), 4.31-4.28 (m, 2H, OCH2CH2CH2O), 4.18 (d, 2H, J=12.2 Hz, Troc CH2), 4.15-4.13 (m, 2H, OCH2CH2CH2O), 3.95-3.91 (m, 8H, OCH3×2, H11a), 3.35 (dd, 2H, J=11.0, 16.6 Hz, H1), 2.84 (d, 2H, J=16.6 Hz, H1), 2.46-2.44 (m, 2H, OCH2CH2CH2O), 0.89 (s, 18H, TBS CH3×6), 0.29 and 0.26 (s×2, 12H, TBS CH3×4); 13C NMR (100.6 MHz, CDCl3) δ 164.9 (Cquat), 153.6 (Cquat), 151.0 (Cquat), 149.5 (Cquat), 136.0 (Cquat), 127.7 (Cquat), 123.9 (Cquat), 121.0 (C3), 114.0 (C9), 110.9 (C6), 95.1 (Troc CCl3), 86.3 (C11), 74.8 (Troc CH2), 65.0 (OCH2CH2CH2O), 60.6 (C11a), 56.2 (OCH3), 34.4 (C1), 28.8 (OCH2CH2CH2O), 25.6 (TBS CH3), 17.8 (TBS Cquat); IR (CHCl3) 3020, 2957, 2860, 1725, 1674, 1651, 1604, 1516, 1466, 1454, 1431, 1409, 1329, 1312, 1274, 1216, 1138, 1113, 1083, 1042, 1006, 900, 840, 757, 668, 646, 610 cm−1; MS (ES), m/z (relative intensity) 1461 ([M+21]+., 100), 1440 (M+., 55).

1. customthe complete consumption of the starting material
2. additionThe mixture was poured into cold saturated NaHCO3 (60 mL)
3. extractionextracted with DCM (3×80 mL)
4. washThe combined organic layers were then washed with saturated CuSO4 (2×125 mL), brine (125 mL)
5. dry with materialdried (MgSO4)
6. filtrationFiltration and evaporation of the solvent
7. customafforded the crude product which
8. customwas purified by flash column chromatography (80:20 v/v hexane/EtOAc)