[F:1][C:2]1[CH:7]=[C:6]([F:8])[CH:5]=[C:4]([CH2:9][C:10](=O)[C:11]2[CH:16]=[CH:15][C:14]([CH2:17][C:18]([CH3:21])([CH3:20])[CH3:19])=[CH:13][CH:12]=2)[C:3]=1[N+:23]([O-:25])=[O:24].C([SiH](CC)CC)C.O>FC(F)(F)C(O)=O>[F:1][C:2]1[CH:7]=[C:6]([F:8])[CH:5]=[C:4]([CH2:9][CH2:10][C:11]2[CH:16]=[CH:15][C:14]([CH2:17][C:18]([CH3:19])([CH3:20])[CH3:21])=[CH:13][CH:12]=2)[C:3]=1[N+:23]([O-:25])=[O:24]A solution of the product from step (b) (11.1 g) in trifluoroacetic acid (16 ml) was stirred at room temperature and triethylsilane (12.5 ml) added. The mixture was stirred overnight at room temperature, followed by 3 hours at 50° C. during which further portions of triethylsilane (3 ml each) were added after 1.5 hours and 2.5 hours, then poured into water (250 ml). The latter was extracted with ether (x2) and the combined extracts washed with water (x2), dried over MgSO4, and evaporated under reduced pressure to give an oil which was flash chromatographed through a silica column using ether/hexane (1:4 v/v). The eluate was evaporated under reduced pressure to give 11.0 g of the desired product.
Wird geladen…
