ISSN 1070-4280, Russian Journal of Organic Chemistry, 2011, Vol. 47, No. 11, pp. 1774−1776. © Pleiades Publishing, Ltd., 2011. Original Russian Text © V.N. Valaeva, A.F. Asachenko, P.S. Kulyabin, V.R. Flid, A.Z. Voskoboinikov , 2011, published in Zhurnal Organicheskoi Khimii, 2011, Vol. 47, No. 11, pp. 1734−1736. 1774 SHORT COMMUNICATIONS New Catalyst for Homocoupling of Aryl Halides Based on Nickel Complexes with Diazabutadiene Ligands V. N. Valaeva a,b , A. F. Asachenko a , P. S. Kulyabin a , V. R. Flid b , and A. Z. Voskoboinikov a a Lomonosov Moscow State University, Moscow, Russia b Lomonosov State Academy of Fine Chemical Technology, Moscow, 119571 Russia e-mail: valaeva@gmail.com Received June 3, 2011 DOI: 10.1134/S1070428011110236 N N R 2 R 2 R 1 R 1 R 1 R 1 N N Ic N N Id Ph Ph Symmetric biaryls are commonly prepared by homo- coupling of aryl halides. Nickel catalysts of this reaction are especially attractive due to their availability, ease in handling, and tolerance toward many functional groups. Nowadays many procedures of homocoupling were developed utilizing nickel [1, 2], but the most general was the method first introduced in [3]. In this method NiCl 2 (PPh 3 ) 2 is used where Ni(II) is reduced to Ni(0) with the help of zinc in the presence of Et 4 NI, but the procedure is not free of disadvantages: The necessity to use large amounts of the catalyst (10–50 mol%) and of relatively expensive and toxic ligand; the products often form in a low yield, are difficult to separate by chromatography from triphenylphosphine. Therefore we searched for the other, more efficient and available catalytic systems. As known, in the homocoupling are used not only complexes with phosphine ligands, but also with bipyridyl ligands [1, 2, 4–7]. We found besides that the catalyst based on о-phenanthroline also exhibited a moderate activity in homocoupling of bromobenzene. Therefore we concluded that in this reaction complexes of nickel with easily available diazabutadiene ligands might be used. Thiese complexes were formerly used for preparation of difficultly available ethylene copolymers with polar monomers [8–10]. At the first stage of the research we synthesized diaz- abutadiene ligands containing diverse substituents both at the nitrogen and carbon atoms of the diazabutadiene frame, and then the capability of nickel complexes with these ligands was studied to catalyze the bromobenzene homocoupling in the presence of activated zinc (reducer) and salt additive (Et 4 NI). N N I e N N N N Ib Ia