1.1: N-ethyl-N,N-diisopropylamine / butan-1-ol / 20 °C / Reflux 2.1: sodium hydroxide; water / 4 h / 60 - 80 °C 2.2: 20 °C / pH 2 3.1: triethylamine; phenylphosphoric acid dichloride / dichloromethane / 0 - 20 °C / Inert atmosphere 4.1: boron trichloride / dichloromethane / -15 - 20 °C 4.2: Cooling with ice View Scheme

in toluene T=85°C;

T=150°C;