To obtain the subject compound useful as a raw material for antioxidants for higher alcohols or oils and fats, and for perfumes and drugs by reacting 2,6,6-trimethylcyclohex-2-exe-1,4-dione (referred to as KIP hereafter) with an acylating agent in the presence of a solid catalyst.

This compound of the formula (R is an alkyl, a cycloalkyl, an aryl, etc., specifically a 1-3C alkyl, e.g. methyl) is obtained in a high yield by reacting KIP at 5-40 pts.wt. in the reaction system with an acylating agent such as a 2-4C carboxylic anhydride or a 2-4C carboxylic halide, e.g. acetic anhydride at least twice as much mol as KIP in the presence of a solid catalyst such as a solid acid catalyst, e.g. a strong acid type ion exchange resin or a metal oxide at 0.1-1,000 pts.wt. based on 100 pts.wt. of KIP at 0-150°C. The catalyst after the reaction need not only be neutralized nor removed but can be reused.