0.3 g (13.0 mmol) of sodium was dissolved in 15 ml of ethanol. Next, 2.63 g (10.0 mmol) of 4-dibutylamino-2-methoxybenzaldehyde and 2.22 g (11.0 mmol) of 2-butyl-3,5,5-trimethyl-2-cyclohexenone were dissolved in 5 ml of ethanol and added to the mixture. To this mixture, 0.36 g of ammonium acetate was added and the mixture was stirred with heating at 60° C. for 22 hours. To the mixture, 100 ml of ethyl acetate was added. Washing with a saturated saline solution, drying over anhydrous sodium sulfate, and concentration were performed. The residual liquid was purified by silica gel column chromatography to give 465 mg of a dark red oily matter (yield: 10.6%).
