1: 13 percent / t-BuOK, <18>crown-6 / dimethylsulfoxide; tetrahydrofuran / 4 deg C, 20 h, RT, 4 d 2: 52 percent / m-chloroperbenzoic acid / CDCl3 / 24 h / Ambient temperature View Scheme

in tetrahydrofuran; dimethyl sulfoxide T=0°C; 2 h;

in tetrahydrofuran; dimethyl sulfoxide 24 h; Ambient temperature;