[Br:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]([C:10]2[CH:15]=[CH:14][C:13]([OH:16])=[C:12]([F:17])[CH:11]=2)=O)=[CH:4][CH:3]=1.[C:18]1(=O)[CH2:23][CH2:22][CH2:21][CH2:20][CH2:19]1>C1COCC1.[Ti](Cl)(Cl)(Cl)Cl.[Zn]>[Br:1][C:2]1[CH:7]=[CH:6][C:5]([C:8](=[C:18]2[CH2:23][CH2:22][CH2:21][CH2:20][CH2:19]2)[C:10]2[CH:15]=[CH:14][C:13]([OH:16])=[C:12]([F:17])[CH:11]=2)=[CH:4][CH:3]=1
Titanium tetrachloride (1.70 mL, 15.5 mmol) was added dropwise to a suspension of zinc powder (2.12 g, 32.4 mmol) in anhydrous THF (60 mL) at RT. After refluxing for 1 h, a mixture of 82 (1.18 g, 4.00 mmol) and cyclohexanone (1.18 g, 12.0 mmol) dissolved in THF (20 mL) was added dropwise. Refluxing was continued for 30 min. The reaction mixture was cooled to RT and filtered through Celite. Water (250 mL) was added and the mixture was extracted with ether (3×100 mL). The combined ethereal extracts were washed with water (200 mL), brine (200 mL), and dried over MgSO4. Concentration followed by flash chromatography (20:1 to 5:1 hexanes:EtOAc) afforded 1.15 g (80%) of compound 83 as a light yellow solid. 1H NMR (400 MHz, CDCl3): δ 1.58 (br s, 6H), 2.20 (m, 4H), 5.10 (br s, 1H), 6.77 (m, 2H), 6.89 (t, J=8.6 Hz, 1H), 6.96 (d, J=8.4 Hz, 2H), 7.39 (d, J=8.4 Hz, 2H).
Wird geladen…
