Reaktion #8695

Reaktionsgleichung

EA

K3PO4

1-bromo-2,4-dimethyl-benzene

→

2-(2,4-dimethyl-phenyl)-malonic acid dimethyl ester

Lösungsmittel

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONwas added under argon
2. 2
   TemperaturThe mixture was refluxed for 96 h
3. 3
   Filtrationfiltered
4. 4
   SonstigeThe filtrate was evaporated
5. 5
   Sonstigethe resulting brown oil was purified on silica gel eluting with heptane:EA 4:1 to 1:1
6. 6
   workup.DISTILLATIONfollowed by distillation (bp 95–100° C. at 0.064 mbar)

Vorschrift

(In analogy to a procedure given in J. Am. Chem. Soc. 122 (2000), 1360–1370.) To a suspension of Pd(OAc)2 (758 mg), 2-(di-tert.-butlylphosphino)-biphenyl (2.02 g) and K3PO4 (65.95 g) in THF (350 ml) dimethylmalonate (21.42 g) and 1-bromo-2,4-dimethyl-benzene (25 g) was added under argon. The mixture was refluxed for 96 h, cooled to rt and diluted with EA (300 ml) and filtered. The filtrate was evaporated and the resulting brown oil was purified on silica gel eluting with heptane:EA 4:1 to 1:1 followed by distillation (bp 95–100° C. at 0.064 mbar) to give 2-(2,4-dimethyl-phenyl)-malonic acid dimethyl ester (5.66 g) as a colourless oil. 1H-NMR(300 MHz, CDCl3): 2.30(s, 6H), 3.75(s, 6H), 4.87(s, 1H), 6.98–7.05(m, 2H), 7.25–7.28(m, 1H).

Quelle