반응 #362036

반응 방정식

2-chloro-3-pyridinecarboxylic acid, methyl ester

vinyltributyltin

2,6-ditertbutyl-4-methylphenol

N,N-dimethylformamide

vinyltributyltin

→

2-Ethenyl-3-pyridinecarboxylic acid, methyl ester

2-ethenyl-3-pyridinecarboxylic acid, methyl ester

용매

ethyl acetate

반응 조건

후처리

1. 1
   온도The mixture is heated further at 40° C. for 61 hours
2. 2
   농축concentrated at 60° C./5 mm
3. 3
   기타to leave a greenish oil that
4. 4
   여과filtered through a pad of silica gel (230-400 mesh)
5. 5
   workup.ADDITIONThe filtrate is diluted with additional ethyl acetate
6. 6
   세척the organic phase is washed with water
7. 7
   기타dried
8. 8
   농축concentrated to an oil
9. 9
   workup.DISTILLATIONThe oil is distilled, with material
10. 10
    기타collected in the 80°-95° C./0.14 mm ranger

실험 절차

2-Ethenyl-3-pyridinecarboxylic acid, methyl ester (12) is prepared as follows: a mixture of 19.7 g (115 mmol) of 2-chloro-3-pyridinecarboxylic acid, methyl ester (11), 38.3 g (120.8 mmol) of vinyltributyltin, 1.48 g (2.1 mmol) of bis(triphenylphosphine)palladium (II) chloride 100 mg of 2,6-ditertbutyl-4-methylphenol, and 250 mL of N,N-dimethylformamide is stirred at 55° C. for 7 hours, then treated with 1.63 g 15.1 mmol) of additional vinyltributyltin and 1 g of palladium catalyst. The mixture is heated further at 40° C. for 61 hours, then concentrated at 60° C./5 mm to leave a greenish oil that is dissolved in ethyl acetate and filtered through a pad of silica gel (230-400 mesh). The filtrate is diluted with additional ethyl acetate and the organic phase is washed with water, dried, and concentrated to an oil. The oil is distilled, with material collected in the 80°-95° C./0.14 mm ranger to leave 24.5 g of an oil that is ca. 75% product by GC. The oil is dissolved in dichloromethane:hexanes (1:1) and loaded onto an 8 x 15 cm of silica gel column (230-400 mesh). The column is eluted with the same solvent as above with 500 mL fractions collected. Product fractions are combined and carefully distilled at 65°-67° C./0.15 mm to leave 13.6 g of clear oil, >95% pure by GC, that is sufficiently pure to use directly in the next step.

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