C([Li])CCC.[CH3:6][N:7]([CH3:12])[S:8]([CH3:11])(=[O:10])=[O:9].[C:13]1(=[N:19][S:20]([C:22]([CH3:25])([CH3:24])[CH3:23])=[O:21])[CH2:18][CH2:17][CH2:16][CH2:15][CH2:14]1>C1COCC1>[CH3:6][N:7]([CH3:12])[S:8]([CH2:11][C:13]1([NH:19][S:20]([C:22]([CH3:25])([CH3:24])[CH3:23])=[O:21])[CH2:18][CH2:17][CH2:16][CH2:15][CH2:14]1)(=[O:10])=[O:9]n-Butyllithium (1.3 eq, 8.07 mL of a 1.6M soln in hexanes) was added dropwise to a cooled (−78° C.) solution of N,N-dimethyl methanesulfonamide (1.35 eq, 1.65 g) in 100 mL of dry THF under anhydrous atmosphere. The mixture was stirred for 30 min at that temperature and then transferred via cannula to a solution of sulfinyl imine 1200-B (2.0 g) in 100 mL of dry THF at −78° C. After addition was completed, the reaction mixture was stirred for 1 h. The reaction was quenched at −78° C. by addition of 20 mL of aqueous saturated ammonium chloride solution. The mixture was allowed to reach room temp and then partitioned between dichloromethane (300 mL) and aqueous saturated sodium bicarbonate solution (300 mL). The aqueous layer was back extracted with dichloromethane (2×200 mL). The combined organic layers were dried over magnesium sulfate, filtered and concentrated. The residue was chromatographed on silica gel (gradient:dichloromethane/hexanes; 1:1 to 30% acetone in dichloromethane/hexanes; 1:1) to afford the product 1200-C (1.36 g; 42%) as a colorless oil.
Wird geladen…