2-(4-isobutylphenyl)propionaldehyde

2-(4-Isobutylphenyl)propanal is an impurity of the drug Ibuprofen (I140000), a selective cyclooxygenase inhibitor that also inhibits PGH synthase-1 and PGH synthase-2 with comparable potency.

Numerous methods are known for the synthesis of 2-(4-isobutylphenyl)propionaldehyde. It can be prepared by reaction of p-isobutylacetophenone with methyl chloroacetate using sodium methoxide as catalyst, followed by reaction of the glycidic ester with BF3 to give 2- hydroxy-3-(4-isobutylphenyl)-3-butenoic acid methyl ester, which is subsequently treated with mineral acid Avariant of the process is the hydrolysis of the intermediately formed glycidic ester with alkali to give the corresponding salt of glycidic acid, which is then decarboxylated. In addition, 2-(4-isobutylphenyl)propanal is formed by isomerization of 2-(4-isobutylphenyl)- 2-methyloxirane on Al2O3-SiO2 or anhydrous ZnCl2, by reaction of 1-(4-isobutylphenyl)- 1-chloroethane with dimethylformamide in the presence of Li or Na in tetrahydrofuran, and in good yields by Rh- or Co-catalyzed hydroformylation of p-isobutylstyrene.