Yield given. Multistep reaction;

1: With potassium salt of diphenylphosphine anion in tetrahydrofuran T=-78°C; 2 h; Inert atmosphere; 2: With hydrogenchloride in tetrahydrofuran; water T=20°C; 0.5 h; Inert atmosphere;

n-butyllithium in tetrahydrofuran -105 degC -> room temp.;

1.1: potassium salt of diphenylphosphine anion / tetrahydrofuran / 2 h / -78 °C / |Inert atmosphere 1.2: 0.5 h / 20 °C / |Inert atmosphere 2.1: sodium hydroxide / tetrahydrofuran; water / 12 h / |Inert atmosphere View Scheme