Cesium carbonate → HCID 18790107, compound

Participants

Reaction Steps

To a vigorously stirring suspension of cesium carbonate (0.88 g, 2.69 mmol) in anhydrous DMF (10 mL) under a nitrogen atmosphere is added 3,4-dimethoxythiophenol (0.45 g, 2.69 mmol) in a dropwise fashion. The white heterogeneous mixture is stirred for 15 minutes then a solution containing (-)-3-(2-benzenesulfonylethyl)-4-(4-phenylbutyl)-oxetan-2-one (0.50 g, 1.34 mmol) in anhydrous DMF (4 mL) is added. The pale yellow heterogeneous mixture is stirred at room temperature for 2.5 hours then partitioned between water (50 mL) and diethyl ether (50 mL). Aqueous HCl (1 N, 5 mL) is added and the layers are separated. The aqueous phase is extracted with diethyl ether (2×20 mL) and the combined organic extracts are washed with water (10×10 mL), brine (20 mL), dried over anhydrous MgSO4, filtered and concentrated to afford a pale yellow oil. The crude product is chromatographed on silica gel (CH2Cl2 →CH2Cl2 :MeOH, 19:1) to afford a colorless oil which is dissolved in diethyl ether (100 mL) and washed with water (10×30 mL) to remove residual DMF. The organic phase is washed with brine (30 mL), dried over anhydrous MgSO4, filtered and concentrated to afford (-)-2-(2-benzenesulfonylethyl)-3-(3,4-dimethoxyphenyl-sulfanyl)-7-phenylheptanoic acid (0.57 g, 78%) as a white foam. TLC analysis [hexane/EtOAc, 2:1, Rf (lactone)=0.65, Rf (acid)=0.05]. [α]23D -35.3° (c 1.0, CHCl3); 1H NMR (300 MHz, CDCl3) δ 1.31-1.70 (m, 6H), 2.00 (m, 1H), 2.30 (m, 1H), 2.56 (m, 3H), 2.95 (m, 1H), 3.25 (m, 2H), 3.84 (s, 3H), 3.85 (s, 3H), 6.77 (d, J=8.2 Hz, 1H), 6.95 (m, 2H), 7.15 (m, 3H), 7.25 (m, 2H), 7.55 (m, 2H), 7.65 (m, 1H), 7.90 (m, 2H) ppm. Mass spectrum (FAB) m/z 542 (M)+.

Provenance & Evidence