A New Preparation of 7-methylindanone

In connection with other studies, we found it necessary to prepare 7-methylindanone, II. The literature records^1,2 two preparations of II, neither of which is completely satisfactory since each yields a mixture of 7-methyl- and 5-methylindanone. Both procedures involve cyclizaton of m-tolylpropionic acid or its chloride. Acrylophenones are known to cyclize to indanones under acidic conditions³ and this type of reaction was investigated as a better method for the preparation of 7-methylindanone [Reaction (1)].