[OH:1]/[N:2]=[C:3](/[C:9](=[O:11])[CH3:10])\[C:4]([O:6][CH2:7][CH3:8])=[O:5].Br[C:13]1([CH3:19])[CH2:18][CH2:17][CH2:16][CH2:15][CH2:14]1>O1CCOCC1.FC(F)(F)S([O-])(=O)=O.[Ag+]>[CH3:19][C:13]1([O:1]/[N:2]=[C:3](/[C:9](=[O:11])[CH3:10])\[C:4]([O:6][CH2:7][CH3:8])=[O:5])[CH2:18][CH2:17][CH2:16][CH2:15][CH2:14]1Ethyl (Z)-2-hydroxyimino-3-oxobutyrate (3.18 g, 20 mmol) and 1-bromo-1-methylcyclohexane (3.54 g, 20 mmol) in dry dioxane (15 ml) were stirred together in the dark and silver trifluoromethanesulphonate (5.13 g, 20 mmol) was added portionwise over 4 h. After a total of 100 h the mixture was filtered through Kieselguhr and the residue was washed well with dioxane. The filtrate was evaporated in vacuo, toluene was added and evaporated in vacuo and the residual oil was dissolved in ethyl acetate and washed with dilute aqueous NaHCO3, followed by water and brine. Ater drying (MgS4) the ethyl acetate was evaporated in vacuo and the residual oil was chromatographed on silica gel, to give the title compound as a yellow oil (3.49 g; 69%); νmax (CH2Cl2) 2945, 1740, 1685, 1370, 1320, 1235, 1070 and 1005 cm-1 ; δH (60 MHz, CDCl3) 1.35 (6H, s superimposed on t), 1.4-2.0 (10H, m), 2.37 (3H, s), 4.55 (2H, q, J 7 Hz).
Wird geladen…
