Preparation of N-aryl-N-(3-aryl-1,2,4-oxadiazol-5-yl)amines 2 [8]. Reagents and conditions: (a) hydroxylamine hydrochloride (1 eq.), EtOH, reflux, 5-10 h; (b) aq. Na2CO3, extraction with EtOAc; (c) 0.2 M solution of 3 in dry DMF, 2.1 eq. of R2-N = C = N-R2 carbodiimides, 120°C, 18-36 h.