in N,N-dimethyl-formamide 1.) 1 h, ice-bath, 2.) 3 h, room temp.;

1: 63 percent / HClO4 / 1.) 1 h, -15 deg C, 2.) 2 h, room temp. 2: 50 percent / H2SO4, NaN3 / H2O / 1.) 1 h, ice-bath, 2.) 5 h, room temp. View Scheme