Cl[C:2]1[CH:7]=[C:6]([O:8][CH3:9])[C:5]([Cl:10])=[CH:4][N:3]=1.B1(C=C)OB([CH:17]=[CH2:18])OB(C=C)O1.C1C=CN=CC=1.C([O-])([O-])=O.[K+].[K+]>COCCOC.CC(=O)OCC.C1C=CC([P]([Pd]([P](C2C=CC=CC=2)(C2C=CC=CC=2)C2C=CC=CC=2)([P](C2C=CC=CC=2)(C2C=CC=CC=2)C2C=CC=CC=2)[P](C2C=CC=CC=2)(C2C=CC=CC=2)C2C=CC=CC=2)(C2C=CC=CC=2)C2C=CC=CC=2)=CC=1>[Cl:10][C:5]1[C:6]([O:8][CH3:9])=[CH:7][C:2]([CH:17]=[CH2:18])=[N:3][CH:4]=1To a solution of 2,5-dichloro-4-methoxy-pyridine (730 mg, 4.10 mmol) in DME (16 mL), 2,4,6-trivinylcyclotriboroxane pyridine complex (987 mg, 4.10 mmol) followed by 2 M aq. K2CO3 solution (4 mL) is added. The solution is degassed and put under argon before Pd(PPh3)4 (95 mg, 82 μmol) is added. The mixture is stirred for 18 h at 80° C. The mixture is cooled to rt, diluted with EA (200 mL) and washed with water and sat. aq. NaHCO3 solution. The org. extract is dried over MgSO4, filtered and concentrated. The remaining brown residue is purified by CC on silica gel eluting with heptane:EA 9:1 to give 5-chloro-4-methoxy-2-vinyl-pyridine (402 mg) as a pale yellow oil; LC-MS: tR=0.53 min, [M+1]+=169.98; 1H NMR (CDCl3): δ 3.98 (s, 3H), 5.52 (d, J=10.5 Hz, 1H), 6.20 (d, J=17.3 Hz, 1H), 6.76 (dd, J=17.3, 10.8 Hz, 1H), 6.88 (s, 1H), 8.41 (s, 1H).
Wird geladen…
