toluene-4-sulfonic acid; orthoformic acid triethyl ester in toluene 24 h; Reflux;

p-toluenesulfonic acid monohydrate in toluene 4 h; Reflux;

1: 83 percent / NH4Cl / acetonitrile; H2O / 24 h / Ambient temperature 2: 85 percent / p-TsOH / benzene / 2.5 h / Heating 3: 98 percent / 10percent NaOH / 3 h / Heating 4: 1.) 25percent aq. NaOH / 1.) HMPA, 2.) HMPA, 1 h View Scheme

1: 85 percent / p-TsOH / benzene / 2.5 h / Heating 2: 98 percent / 10percent NaOH / 3 h / Heating 3: 1.) 25percent aq. NaOH / 1.) HMPA, 2.) HMPA, 1 h View Scheme

1: 98 percent / 10percent NaOH / 3 h / Heating 2: 1.) 25percent aq. NaOH / 1.) HMPA, 2.) HMPA, 1 h View Scheme

sodium hydroxide 1.) HMPA, 2.) HMPA, 1 h; Yield given. Multistep reaction;