1: 85 percent / Al2O3 / diethyl ether / 4 h / Ambient temperature 2: 1.) MeONa, 2.) conc. H2SO4 / 1.) MeOh, 2.) -35 deg C, 10 min 3: 78 percent / NaOH / ethanol View Scheme

1: 75 percent / Amberlyst A21 / diethyl ether / 24 h / Ambient temperature 2: 1.) MeONa, 2.) conc. H2SO4 / 1.) MeOh, 2.) -35 deg C, 10 min View Scheme

1: 64 percent / Al2O3 / diethyl ether / 7 h / Ambient temperature 2: 1.) MeONa, 2.) conc. H2SO4 / 1.) MeOh, 2.) -35 deg C, 10 min View Scheme

1: 64 percent / Al2O3 / diethyl ether / 7 h / Ambient temperature 2: 1.) MeONa, 2.) conc. H2SO4 / 1.) MeOh, 2.) -35 deg C, 10 min 3: 90 percent / NaOH / diethyl ether / 3 h View Scheme