C[Si](C)(C)N[Si](C)(C)C.C1(P(C2CCCCC2)C2C=CC=CC=2C2C=CC=CC=2N(C)C)CCCCC1.[C:38]([O:42][C:43](=[O:45])[CH3:44])([CH3:41])([CH3:40])[CH3:39].[Cl:46][C:47]1[CH:52]=[C:51](Cl)[CH:50]=[CH:49][N:48]=1>C1(C)C=CC=CC=1.C(=CC(C=CC1C=CC=CC=1)=O)C1C=CC=CC=1.[Pd]>[C:38]([O:42][C:43](=[O:45])[CH2:44][C:51]1[CH:50]=[CH:49][N:48]=[C:47]([Cl:46])[CH:52]=1)([CH3:41])([CH3:40])[CH3:39]Hexamethyl disilazane (5.45 g, 33.8 mmol) is dissolved in dry toluene (80 ml) under an atmosphere of argon. After thoroughly purging the solvent with argon, the solution is cooled to −78° C., and n-BuLi (21.1 ml of a 1.6 M solution in hexanes, 33.8 mmol) is added. The mixture is stirred for 15 minutes at −78° C. and for 15 minutes at RT, whereupon a clear solution is obtained. Palladium dibenzylideneacetone (Pd2(dba)3, 743 mg, 0.81 mmol) and (2′-dicyclohexylphosphanyl-biphenyl-2-yl)-dimethyl-amine (670 mg, 1.70 mmol) are added. The mixture is stirred for 10 minutes at RT, then it is cooled to −10° C. Acetic acid tert-butyl ester (3.61 g, 31.08 mmol) is slowly added neat. After 10 minutes at −10° C., 2,4-dichloropyridine (4.00 g, 27.03 mmol) is added in one portion. The reaction mixture is allowed to warm to RT. After 1 h, TLC analysis indicated complete consumption of starting materials. The reaction mixture is diluted with EtOAc and poured into a saturated aqueous NH4Cl solution. The organic layer is separated, washed with brine, dried over Na2SO4, and the solvent is evaporated. The residue is purified by FCC (hexanes/EtOAc, gradient from 97:3 to 90:10) to afford the title compound. 1H NMR (CDCl3, 400 MHz): δ 1.44 (s, 9H), 3.51 (s, 2H), 7.15 (dd, J=1 Hz, 4 Hz, 1H), 7.27 (d, J=1 Hz, 1H), 8.32 (d, J=4 Hz). ES+−MS: 228.2, 230.1 (Cl) [M+H]+.
読み込み中…
