1: HCl / ethanol / 0 - 25 °C 2: 1.) p-TsOH; 2.) m-CPBA / 1.) C6H6, reflux; 2.) CH2Cl2, 0 deg C to room temp. 3: 96 percent / K2CO3 / acetone / Heating 4: 60 percent / NaH, KH / dimethylsulfoxide / 24 h / 20 - 30 °C 5: p-TsOH*Py / acetone; H2O / 10 h / Heating View Scheme

2,3-dicyano-5,6-dichloro-p-benzoquinone in 1,4-dioxane 20 h; Heating;

1: 20 percent / 1.) pent-1-ynylcopper, hexamethylphosphoric triamide / diethyl ether / 1.) -20 deg C, room temperature, 1 h, 2.) -40 deg C, 10 min; -20 deg C, 30 min; 0 deg C, 1 h 2: 87 percent / m-chloroperbenzoic acid / CHCl3 / 1 h / -20 - -10 °C View Scheme

toluene-4-sulfonic acid in toluene 12 h; Heating / reflux;

1: 92 percent / Et3N / toluene / 19 h / Ambient temperature 2: 99 percent / toluene-p-sulphonic acid / benzene / 2 h / Heating 3: 99 percent / BuLi / hexane; tetrahydrofuran / 1.) -35 deg C, 30 min, 2.) -78 deg C, 120 min 4: 4M HCl / acetone / 18 h / Heating 5: 75 percent / H2 / Raney nickel / methanol / 6 h / Heating View Scheme

copper(l) iodide; tributylphosphine in diethyl ether; hexane 1.) -78 deg C, 20 min, 2.) -78 deg C, 70 min; -40 deg C, 4 h;

copper diacetate in tetrahydrofuran; diethyl ether 1.) -10 deg C, 50 min, 2.) reflux, 15 min;

1: 94 percent / 12 N aq. HCl / ethanol / 5 h / Ambient temperature 2: p-toluenesulfonic acid / benzene / 4 h / Heating 3: m-chloroperbenzoic acid / CH2Cl2 / 1.) 0 deg C, 1 h, 2). RT, 4 h 4: 1.) sodium hydride / 1.) DMF, RT, 2.) DMF, 70 deg C, 20 h 5: sodium hydride, potassium hydride / dimethylsulfoxide / Ambient temperature 6: pyridinium p-toluenesulfonate, water / acetone / 10 h / Heating View Scheme