Abstract
Abstract: The arylation of pyrazole and derivatives can beachieved by coupling arenediazonium species (formedin situ from anilines) by using a catalytic system that em-ploys low-toxicity and inexpensive copper metal undervery mild and ligand-free conditions (T = 20 8C). Fromother nitrogen heterocycles, the presence of an additive(NBu4I) significantly improves the efficiency of the catalyticsystem. These results represent the first examples of CÀNbond formation from arenediazonium species.