Hydrochloric Acid → 3-(4-Propyl-phenyl)-propionaldehyde dimethylacetal

A reaction flask was charged with 3-(4-propyl-phenyl)-propionaldehyde (147 g, prepared as above), methanol (500 mL), and TMOF (90 g). The reaction mass was cooled to 0° C. and hydrochloric acid (37%, 1 g) was added in one portion. The reaction was exothermic and the temperature rose to 23° C. The reaction mass was quenched with sodium methoxide in methanol (25%, 10 g) and the solvent was removed by evaporation. The crude intermediate product 3-(4-propyl-phenyl)-propionaldehyde dimethylacetal was provided and confirmed by the NMR analysis. 3-(4-Propyl-phenyl)-propionaldehyde dimethylacetal was further treated with phosphoric acid (10 g) and pyridine (8 g) at 200° C. The reaction mass was aged for 4 hours, during which methanol was recovered in a Dean Stark trap. The reaction mass was then cooled and washed with aqueous sodium carbonate solution. Fractional distillation of the organic layer afforded the product 4-propyl 1-(3-methoxy-2-propen-1-yl)benzene (80 g), which had a boiling point of 101° C. at a pressure of 3 mmHg.