Ethyl 3-(dimethoxymethyl)-crotonate → Ethyl 3-methyl-4-oxobutanoate

A solution of ethyl 3-(dimethoxymethyl)-crotonate (73 g) in ethyl acetate (200 ml) was hydrogenated at 50 psi for 3 h in the presence of 10% palladium on charcoal (7 g). The solution was filtered, evaporated, and the residual oil treated with 0.25 M hydrogen chloride in 75% aqueous methanol for 2 h. To the reaction mixture was added ethyl acetate (300 ml) and water (150 ml). The organic phase was successively washed with sat. sodium bicarbonate solution (3×150 ml), water (100 ml) and dried over magnesium sulfate. The solution was concentrated in vacuo and the residual oil purified by chromatography on silica gel eluting with ethyl acetate-hexane (1:9) to give ethyl 3-formylbutyrate (26.5 g, 48%).