The invention relates to compounds corresponding to formula (I): R4 NN R1 O R2 R3 (I) 5 6 7 8 in which - R2 and R3 together form, with the carbon atoms of the phenyl nucleus to which they are attached, a 6-membered nitrogenous heterocycle corresponding to one of formula (A), (B) or (C) below: N N O O Ra Ra" N N O Rb Rb" N O Rc Rc" Rc" (A)(B)(C)in which the wavy lines represent the phenyl nucleus to which R2 and R3 are attached. Preparation process and therapeutic use.