Acylation of anisole with methylsuccinic anhydride catalysed by zeolites

The zeolite-catalysed acylation of anisole with methylsuccinic anhydride gave mixture of products. The main component was 4-hydroxy-4,4-bis-(4-methoxyphenyl)-2-methyl-gamma-butyrolactone, which was isolated in 25% yield; the expected keto acids were not formed. In the zeolite-catalysed reaction between 3-(4-methoxybenzoyl)-2-methylpropionic acid and anisole, the gamma-butyrolactone was isolated in 82% yield, indicating that the initially formed keto acid undergoes cyclisation to the lactone. When these reactions were performed with a zeolite deactivated with triphenylphosphine, the lactone was not formed, suggesting that acid sites on the external surface of the zeolite catalyse these reactions.