[CH:1]([O:4][C:5]1[CH:21]=[CH:20][C:8]([O:9][C:10]2[S:11][C:12](/[CH:15]=[CH:16]/[C:17](=[O:19])[CH3:18])=[CH:13][N:14]=2)=[CH:7][CH:6]=1)([CH3:3])[CH3:2].[Cl-].[Ce+3].[Cl-].[Cl-].[BH4-].[Na+]>CO>[CH:1]([O:4][C:5]1[CH:21]=[CH:20][C:8]([O:9][C:10]2[S:11][C:12](/[CH:15]=[CH:16]/[CH:17]([OH:19])[CH3:18])=[CH:13][N:14]=2)=[CH:7][CH:6]=1)([CH3:2])[CH3:3]To a suspension of the product from Example 7C (1.4 g 4.6 mmole) in methanol (45 mL) at 0° C. was added a methanolic solution of 0.4 M cerium(III)chloride (13.8 mL, 5.5 mmole) followed by portion-wise addition of sodium borohydride (175 mg, 4.6 mmole). The reaction mixture was allowed to warm up to room temperature, stirred at room temperature for 15 minutes and quenched with acetone for 30 minutes. The reaction mixture was diluted with ethyl acetate and washed with water (×2) and brine. The reaction mixture was dried over magnesium sulfate filtered and evaporated. The crude product (1.4 g, quantitative) was carried on to the next step without further purification. 1H NMR (300 MHz, CDCl3) δ ppm 1.32 (d, J=6.62 Hz, 3H) 1.34 (d, J=6.25 Hz, 6H) 1.56 (d, J=4.04 Hz, 1H) 4.33-4.46 (m, 1H) 4.47-4.59 (m, 1H) 5.82 (dd, J=15.63, 6.07 Hz, 1H) 6.56 (d, J=16.18 Hz, 1H) 6.83-6.97 (m, 2H) 7.05 (s, 1H) 7.11-7.22 (m, 2H). Mass spectrum DCI 306 (M+H)+.
Wird geladen…
