反应详情

温度

100 °C

To a solution of 2-chloro-6-methylisonicotinic acid ethyl ester (9.92 g, 49.7 mmol), 2,4,6-tri-(2-methyl-propenyl)-cycloboroxane pyridine complex (13.0 g, 49.7 mmol, prepared in analogy to a procedure given by F. Kerins, D. F. O'Shea J. Org. Chem. 67 (2002) 4968-4971), and PPh3 (1.39 g, 8.60 mmol) in DME (120 mL), a solution of 2 M aq. K2CO3 (40 mL) is added. The mixture is degassed and flushed with N2 before Pd(PPh3)4 (580 mg, 0.793 mmol) is added. The mixture is stirred at 100° C. for 20 h before it is cooled to rt, diluted with EA and washed with sat. aq. NaHCO3 (2×200 mL). The org. extract is dried over MgSO4, filtered and evaporated. The crude product is purified by CC on silica gel eluting with heptane:EA 15:1 to give 2-methyl-6-(2-methyl-propenyl)-isonicotinic acid ethyl ester (9.90 g) as a yellow oil; LC-MS: tR=0.44 min, 1H NMR (CDCl3): δ 1.43 (m, 3 H), 1.98 (s, 3 H), 2.09 (s, 3 H), 2.63 (s, 3 H), 4.34-4.46 (m, 2 H), 6.39 (s, 1 H), 7.50 (s, 1 H), 7.56 (s, 1 H).

1. customThe mixture is degassed
2. additionis added
3. temperatureis cooled to rt
4. washwashed with sat. aq. NaHCO3 (2×200 mL)
5. extractionextract
6. dry with materialis dried over MgSO4
7. filtrationfiltered
8. customevaporated
9. customThe crude product is purified by CC on silica gel eluting with heptane:EA 15:1