[Li]CCCC.CN(CCN(C)C)C.[CH:14]([Si:17]([CH:30]([CH3:32])[CH3:31])([CH:27]([CH3:29])[CH3:28])[O:18][C:19]1[CH:24]=[CH:23][CH:22]=[CH:21][C:20]=1[O:25][CH3:26])([CH3:16])[CH3:15].C1C[O:36][CH2:35]C1>CCOC(C)=O>[CH3:26][O:25][C:20]1[C:19]([O:18][Si:17]([CH:14]([CH3:16])[CH3:15])([CH:27]([CH3:29])[CH3:28])[CH:30]([CH3:32])[CH3:31])=[C:24]([CH:23]=[CH:22][CH:21]=1)[CH:35]=[O:36]nBuLi (2.5 M in hexanes) (36 mmol) is mixed with TMEDA (36 mmol) at 0° C. in a dry round bottom flask for 10 minutes. A solution of triisopropyl-(2-methoxy-phenoxy)-silane (24 mmol) in 25 mL of dry THF is added to the above mixture. The mixture is warmed up to room temperature in 2 hours by removal of the ice bath. The slightly yellow solution is then transferred to another dry flask containing dry 7.5 mL of DMF at room temperature. The mixture is stirred overnight. HCl (1 M) is added to the mixture to quench the reaction. The mixture is diluted with EtOAc (100 mL), washed with HCl (1 M) (2×100 mL) and brine (50 mL) and finally dried over anhydrous Na2 SO4. Purification is accomplished by silica flash chromatography (5% EtOAc/hexane) to yield 3-methoxy-2-triisopropylsilanyloxy-benzaldehyde as a colorless oil which needs to be stored at low temperatures: 1H NMR (400 MHz, CDCl3) δ 10.4 (s, 1H), 7.42 (dd, J1=7.7 Hz, J2=1.7 Hz, 1H), 7.67 (d, J1=8 Hz, J2=1.7 Hz, 1H), 7.04 (t, J=8.4 Hz, 1H), 3.96 (s, 3H), 1.26-1.35 (m, 3H), 1.13 (s, 9H), 1.12 (s, 9H). LC/MS (ES+): (M+1) 309.2. Rf=0.4 (5% EtOAc/hexane).
読み込み中…
