[CH3:1][C:2]1[CH:18]=[C:17]([O:19][Si:20]([CH:27]([CH3:29])[CH3:28])([CH:24]([CH3:26])[CH3:25])[CH:21]([CH3:23])[CH3:22])[CH:16]=[C:15]([CH3:30])[C:3]=1[CH2:4][C:5]1[CH:10]=[CH:9][C:8]([O:11][CH2:12][O:13][CH3:14])=[CH:7][CH:6]=1.CN(CCN(C)C)C.[Li]CCCC.CN([CH:47]=[O:48])C>CCOCC>[CH3:30][C:15]1[CH:16]=[C:17]([O:19][Si:20]([CH:27]([CH3:29])[CH3:28])([CH:21]([CH3:23])[CH3:22])[CH:24]([CH3:26])[CH3:25])[CH:18]=[C:2]([CH3:1])[C:3]=1[CH2:4][C:5]1[CH:10]=[CH:9][C:8]([O:11][CH2:12][O:13][CH3:14])=[C:7]([CH:6]=1)[CH:47]=[O:48]To a solution of 4-(2,6-dimethyl-4-triisopropylsilanyloxybenzyl)-methoxymethoxybenzene (2.0 g, 4.66 mmol) in ether was added TMEDA (1.05 mL, 6.99 mmol), followed by nBuLi (2.5 M in THF, 2.8 mL) at −20° C. The reaction mixture was warmed up to 0° C. and stirred for 1 h DMF (0.72 mL, 9.32 mmol) was then added and after stirring at 0° C. for 2 h, the reaction mixture was quenched with a saturated solution of NH4Cl and diluted with EtOAc. The water layer was extracted with EtOAc and the combined organic extracts were dried (MgSO4), filtered and concentrated to give the crude product 5-(2,6-dimethyl-4-triisopropylsilanyloxybenzyl)-2-methoxymethoxy-benzaldehyde (2.1 g, 98%): 1H NMR (300 MHz, d6-DMSO): δ 10.33 (s, 1H), 7.24 (m, 3H), 6.58 (s, 2H), 5.31 (s, 2H), 3.91 (s, 2H), 3.33 (s, 6H), 1.23 (m, 3H), 1.06 (m, 18H). TLC conditions: Uniplate silica gel, 250 microns; Mobile phase=ethyl acetate-hexanes (1:9); Rf=0.55.
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