in tetrahydrofuran T=60°C; 48 h;

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

1.1: sodium hydride / dimethylformamide / 1 h / 0 °C 1.2: 95 percent / dimethylformamide / 2 h / 20 °C 2.1: potassium tert-butoxide; n-butyllithium; tetramethylethylenediamine / hexane; tetrahydrofuran / 0.5 h / 20 °C 2.2: 97 percent / hexane; tetrahydrofuran / 4.5 h / -78 - 20 °C 3.1: 93 percent / aq. hydrochloric acid / ethanol; CH2Cl2 / Heating 4.1: 90 percent / aq. sodium hydroxide; tetrabutylammonium hydrogen sulfate / 18 h / 20 °C 5.1: 57 percent / boron tribromide / CH2Cl2 / 4.5 h 6.1: 91 percent / tetrahydrofuran / 48 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: 90 percent / aq. sodium hydroxide; tetrabutylammonium hydrogen sulfate / 18 h / 20 °C 2: 57 percent / boron tribromide / CH2Cl2 / 4.5 h 3: 91 percent / tetrahydrofuran / 48 h / 60 °C View Scheme

1: 93 percent / aq. hydrochloric acid / ethanol; CH2Cl2 / Heating 2: 90 percent / aq. sodium hydroxide; tetrabutylammonium hydrogen sulfate / 18 h / 20 °C 3: 57 percent / boron tribromide / CH2Cl2 / 4.5 h 4: 91 percent / tetrahydrofuran / 48 h / 60 °C View Scheme

1: 57 percent / boron tribromide / CH2Cl2 / 4.5 h 2: 91 percent / tetrahydrofuran / 48 h / 60 °C View Scheme