1: TsOH / tetrahydrofuran; CH2Cl2 / Ambient temperature 2: NaOH / tetrahydrofuran; H2O / 5 h / Ambient temperature 3: 1.) pyridine, 2.) aq.AcOH / 1.) CH2CH2, reflux, 15 h, 2.) pyridine, r.t., overnight 4: 1.) hydroquinone, 2.) KOH, 3.) TsOH / 1.) 140 deg C, 36 h, 2.) aq.MeOH, r.t., overnight, 3.) THF, r.t., overnight View Scheme

potassium hydroxide; toluene-4-sulfonic acid; hydroquinone 1.) 140 deg C, 36 h, 2.) aq.MeOH, r.t., overnight, 3.) THF, r.t., overnight; Yield given. Multistep reaction;

1: TsOH / tetrahydrofuran; CH2Cl2 / Ambient temperature 2: NaOH / tetrahydrofuran; H2O / 5 h / Ambient temperature 3: 1.) pyridine, 2.) aq.AcOH / 1.) CH2CH2, reflux, 15 h, 2.) pyridine, r.t., overnight 4: 1.) hydroquinone, 2.) KOH, 3.) TsOH / 1.) 140 deg C, 36 h, 2.) aq.MeOH, r.t., overnight, 3.) THF, r.t., overnight View Scheme

potassium hydroxide; toluene-4-sulfonic acid; hydroquinone 1.) 140 deg C, 36 h, 2.) aq.MeOH, r.t., overnight, 3.) THF, r.t., overnight; Yield given. Multistep reaction;

1: TsOH / tetrahydrofuran; CH2Cl2 / Ambient temperature 2: NaOH / tetrahydrofuran; H2O / 5 h / Ambient temperature 3: 1.) pyridine, 2.) aq.AcOH / 1.) CH2CH2, reflux, 15 h, 2.) pyridine, r.t., overnight 4: 1.) hydroquinone, 2.) KOH, 3.) TsOH / 1.) 140 deg C, 36 h, 2.) aq.MeOH, r.t., overnight, 3.) THF, r.t., overnight View Scheme

potassium hydroxide; toluene-4-sulfonic acid; hydroquinone 1.) 140 deg C, 36 h, 2.) aq.MeOH, r.t., overnight, 3.) THF, r.t., overnight; Yield given. Multistep reaction;