The selective synthesis of N-aryl or N, N′-diaryl piperazines and trimethylene (bis) piperidines from the corresponding diamines and aryl chlorides using a catalyst combination of Ni (0) associated to 2, 2′-bipyridine is described. The Ni/2, 2′-bipyridine catalyst is also effective for the sequential arylation of piperazine. The preparation of novel and unsymmetrical 1, 4-diaryl piperazines is reported.