1.1: potassium tert-butoxide; n-butyllithium; tetramethylethylenediamine / hexane; tetrahydrofuran / 0.5 h / 20 °C 1.2: 97 percent / hexane; tetrahydrofuran / 4.5 h / -78 - 20 °C 2.1: 93 percent / aq. hydrochloric acid / ethanol; CH2Cl2 / Heating 3.1: 90 percent / aq. sodium hydroxide; tetrabutylammonium hydrogen sulfate / 18 h / 20 °C 4.1: 57 percent / boron tribromide / CH2Cl2 / 4.5 h 5.1: 31 percent / tetrahydrofuran / 43 h / 60 °C View Scheme

1.1: potassium tert-butoxide; n-butyllithium; tetramethylethylenediamine / hexane; tetrahydrofuran / 0.5 h / 20 °C 1.2: 97 percent / hexane; tetrahydrofuran / 4.5 h / -78 - 20 °C 2.1: 93 percent / aq. hydrochloric acid / ethanol; CH2Cl2 / Heating 3.1: 90 percent / aq. sodium hydroxide; tetrabutylammonium hydrogen sulfate / 18 h / 20 °C 4.1: 57 percent / boron tribromide / CH2Cl2 / 4.5 h 5.1: 91 percent / tetrahydrofuran / 48 h / 60 °C View Scheme

1: 4-hydroxy-4'-methoxybenzophenone With sodium hydride in N,N-dimethyl-formamide T=0°C; 1 h; 2: chloromethyl methyl ether in N,N-dimethyl-formamide T=20°C; 2 h;