Copper-catalyzed coupling of aryl boronic acids with hydrazine hydrate

N-Arylation is one of the most challenging C-X coupling reactions. Despite the revolutionary achievements of palladium catalysis, classical Ullmann and Goldberg reactions are still very useful [1]. Arylation of hydrazines, which are a special class of nitrogen compounds, is of high interest because it is widely used in the synthesis of natural products, pharmaceutical ,and agrochemical compounds, as well as polymers and materials [2]. Arylboronic acids have been widely used in N-arylation of arylamines through the amination strategies developed by the various research groups [3]. The development of new processes using cheap and abundant amino sources as feedstocks in the synthesis of aromatic amines remains a highly attractive goal. In this work, a copper-catalyzed N-arylation process for the synthesis of 1,1-diphenyl hydrazine derivatives (3a-3i) by reaction of aryl boronic acids (1) with hydrazine hydrate (2) has been developed (Scheme 1). Importantly, this transformation is very practical and it does not require the use of strong bases, expensive ligands or rigorous exclusion of air and moisture.