water; scandium tris(trifluoromethanesulfonate) in acetonitrile 24 h; Ambient temperature;

1: With bismuth trifluoromethanesulphonate; water in acetonitrile 1.5 h; 2: With 2,2,6,6-tetramethyl-1-piperidinyloxy, free radical; iodosylbenzene in acetonitrile 3 h;

triethylsilane; iron(III) chloride in nitromethane T=0°C; 24 h;