T=20 - 25°C; 240 h;

 in  ethanol 72 h;   

Multi-step reaction with 2 steps 1: 45 percent / pentane / -50 deg C, 5 min; 20-25 deg C, 2 h2: 30 percent Spectr. / KH / tetrahydrofuran-d8 / 96 h