1: 22 percent / 1,5-diazabicyclo<5.4.0>undec-5-ene / benzene 2: 92 percent / boron tribromide / hexane; CH2Cl2 / 0.5 h / Heating 3: 90 percent / sodium ethoxide / ethanol / 0.5 h / Ambient temperature 4: 89 percent / acetic anhydride / dimethylsulfoxide / 0.25 h / 100 °C 5: 95 percent / aq. sodium hydroxide / 0.08 h View Scheme

1: 22 percent / 1,5-diazabicyclo<5.4.0>undec-5-ene / benzene 2: 92 percent / boron tribromide / hexane; CH2Cl2 / 0.5 h / Heating 3: 90 percent / sodium ethoxide / ethanol / 0.5 h / Ambient temperature 4: 89 percent / acetic anhydride / dimethylsulfoxide / 0.25 h / 100 °C 5: 95 percent / aq. sodium hydroxide / 0.08 h 6: 86 percent / diethyl ether / 3 h / 0 °C 7: CDCl3 / 3 h / 55 °C 8: methanol View Scheme

1: 22 percent / 1,5-diazabicyclo<5.4.0>undec-5-ene / benzene 2: 92 percent / boron tribromide / hexane; CH2Cl2 / 0.5 h / Heating 3: 90 percent / sodium ethoxide / ethanol / 0.5 h / Ambient temperature 4: 89 percent / acetic anhydride / dimethylsulfoxide / 0.25 h / 100 °C View Scheme

1: 22 percent / 1,5-diazabicyclo<5.4.0>undec-5-ene / benzene 2: 92 percent / boron tribromide / hexane; CH2Cl2 / 0.5 h / Heating 3: 90 percent / sodium ethoxide / ethanol / 0.5 h / Ambient temperature View Scheme