[Br:1]N1C(=O)CCC1=O.[CH3:9][C:10]1[CH:19]=[C:18]([CH3:20])[CH:17]=[CH:16][C:11]=1[C:12]([O:14][CH3:15])=[O:13].C(OOC(=O)C1C=CC=CC=1)(=O)C1C=CC=CC=1.CC1C=CC=C2C=1COC2=O>C(Cl)(Cl)(Cl)Cl>[C:12]([C:11]1[CH:16]=[CH:17][C:18]([CH2:20][Br:1])=[CH:19][C:10]=1[CH3:9])([O:14][CH3:15])=[O:13]
N-Bromosuccinimide (44.9 g) was added to a solution of methyl 2,4-dimethylbenzoate (41.36 g) in carbon tetrachloride containing a trace of dibenzoyl peroxide. The mixture was heated under reflux until no orange colour persisted then cooled, filtered and the filtrate evaporated to leave an oil. This was distilled until ~16 g distilate bp 98°-140°/0.8-5 mm (starting material) had been collected. The residue was then heated at atmospheric pressure until no more methyl bromide was evolved, to give a mixture of the title compound and 4-methylphthalide. Addition of hot petrol and filtration from the phthalide gave after evaporation the title compound. τ (CDCl3) 7.48 (3H, s), 6.21 (3H, s), 5.65 (2H, s), 2.6-2.93 (2H, m), 2.18 (1H, d, J=8 Hz).
Wird geladen…
