1,8-diazabicyclo[5.4.0]undec-7-ene in acetonitrile 1.) reflux, 2.5 h, 2.) room temperature, overnight;

in acetonitrile

1: 1.) Ac2O / 1.) 150 deg C, 2 h, 2.) t-BuOH, 10 deg C, 30 min; 45 deg C, overnoght 2: t-BuOK / 2-methyl-propan-2-ol / 18 h / 50 °C 3: HCl / acetic acid / 2 h / 100 °C 4: 69 percent / DBU / acetonitrile / 1.) reflux, 2.5 h, 2.) room temperature, overnight View Scheme

1: tetrahydrofuran / 0.75 h / -78 °C 2: 1.) Ac2O / 1.) 150 deg C, 2 h, 2.) t-BuOH, 10 deg C, 30 min; 45 deg C, overnoght 3: t-BuOK / 2-methyl-propan-2-ol / 18 h / 50 °C 4: HCl / acetic acid / 2 h / 100 °C 5: 69 percent / DBU / acetonitrile / 1.) reflux, 2.5 h, 2.) room temperature, overnight View Scheme

1: HCl / acetic acid / 2 h / 100 °C 2: 69 percent / DBU / acetonitrile / 1.) reflux, 2.5 h, 2.) room temperature, overnight View Scheme

1: t-BuOK / 2-methyl-propan-2-ol / 18 h / 50 °C 2: HCl / acetic acid / 2 h / 100 °C 3: 69 percent / DBU / acetonitrile / 1.) reflux, 2.5 h, 2.) room temperature, overnight View Scheme