in tetrahydrofuran; diethyl ether T=-15 - 20°C; 5 h;

1: 90 percent / i-PrMgCl / diethyl ether; tetrahydrofuran / 2 h / -15 °C 2: 73 percent / diethyl ether; tetrahydrofuran / 5 h / -15 - 20 °C View Scheme

hydrogen fluoride in acetonitrile 5 h;