To a solution containing 260 g of 4-benzyloxy-3-methoxybenzaldehyde and 200 ml of ethyl crotonate in 1200 ml of N-methylpyrrolidone was gradually added while stirring and cooling at 0° C. 149.6 g of potassium tert.-butoxide. The solution was stirred for 0.5 h after which 200 ml of 10 N NaOH-solution was added and stirred for 0.5 h more at 0° C. The reaction mixture was added to a mixture of hydrochloric acid and ice. The semisolid product was separated and used without purification to the next step.
