Synthesis of o-sulfamidotriazobenzenes from 1,1'-sulfonylbis(benzotriazole)

Easily accessible 1,1'-sulfonylbis(benzotriazole) (Bt2SO2, 1) reacts with secondary amines at room temperature to afford (i) the corresponding o-sulfamidotriazobenzenes 2a-d (53-75%) via concurrent substitution of the first and ring opening of the second benzotriazolyl group and (ii) N-sulfonylbenzotriazoles 3b,c,e,f (7-73%). 1-(Morpholine-4-sulfonyl)-1H-benzotriazole 3c reacts with piperidine, pyrolidine, and N-methylpiperazine under microwave irradiation (120 W) at 120 degrees C for 10 min to give the unsymmetrical sulfamides 4a-c (80-90%).