3-Bromobenzoic acid → 1-Bromo-3-tert-butylbenzene

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A suspension of 4.02 g (20 mmol) of m-bromobenzoic acid (Compound 23) in 10 ml hexane was cooled in an ice-bath under nitrogen and then treated slowly with 40 ml of 2M (80 mmol) trimethylaluminum in hexane. The hexane was removed by distillation under nitrogen and the apparatus modified for reflux. The reaction mixture was then heated in an oil bath at 140-150 degrees C. for 3 hours. The oil bath was then replaced by an ice-water bath and the reaction mixture was quenched by the slow dropwise addition of water. The mixture was acidified with dilute HCl and mixture heated at reflux until the aluminum salts were dissolved. The reaction mixture was allowed to cool and extracted with 3×8 ml ether. The ether extracts were combined, washed with dil. HCl, water and saturated NaCl and then dried (MgSO4). The solvent was removed in-vacuo and the residue distilled to give a mixture of the title compound and 3-(1-methyl-ethenyl)bromobenzene as a colorless oil. A small portion (200 mg) of this mixture was dissolved in 1 ml of methylene chloride and then treated with a solution of 200 mg of m-chloroperbenzoic acid in 4 ml of methylene chloride. The mixture was stirred at room temperature for 1 hour and the methylene chloride removed in-vacuo. The residue was dissolved in hexane and filtered through a short silica column and the filtrate concentrated in-vacuo to give pure title compound as a colorless oil. PMR (CDCl3): & 1.30 (9H, s), 7.25 (1H, m), 7.41 (2H, m), 7.65 (H, t, J~2.1 Hz).

Herkunft & Nachweise