1: (2-propynyloxy)benzene With ethylmagnesium bromide in tetrahydrofuran T=0°C; Metallation; 3 h; 2: acetaldehyde in tetrahydrofuran T=0°C; Grignard reaction; 4 h;

1.1: 94 percent / potassium carbonate / acetone / 50 °C 2.1: ethylmagnesium bromide / tetrahydrofuran / 3 h / 0 °C 2.2: 90 percent / tetrahydrofuran / 4 h / 0 °C View Scheme

1: 92 percent / CrO3; aq. H2SO4 / acetone / 2 h / 20 °C 2: 65 percent / sodium iodide; trimethylsilyl chloride; water / acetonitrile / 4 h / 20 °C 3: 93 percent / sodium borohydride / methanol / 20 °C View Scheme

chromium(VI) oxide; sulfuric acid in acetone T=20°C; Jones oxidation; 2 h;