from first principles PP-I-1

PP-II-17Nickel-Mediated Cross-Coupling of Aryl Halides with Aromatic AldehydesValaeva V.N., Kulyabin P.S., Asachenko A.F., Voskoboynikov A.Z.Department of Chemistry, Lomonosov Moscow State University,1/3 Vorob'evy gory, Moscow 119991, Russiavoskoboy@org.chem.msu.ruSynthesis of symmetrical biarylketones is an important topic of modern preparativechemistry, since many pharmaceuticals and agrochemicals include the functionalizedbenzophenone fragments. Nowadays there are few methods of synthesis of the functionalizedbenzophenones, though all of them possess some drawbacks. Recently, we have studiedhighly active nickel catalysts bearing diaminobutadiene ligands for homocoupling of arylhalides. Here, we discovered that these systems are efficient for synthesis of the substitutedbenzophenones and benzhydrols from aryl halides and aromatic aldehydes.For instance, bromobenzene reacted with benzaldhyde in the presence of 10 mol.% ofNiBr 2 (DME), 5 mol.% of diazabutadine ligand, and 1 eq. of zinc dust to form a mixture ofbenzophenone and benzhydrol in THF at 70 o C. Under the best conditions, benzhydrol wasobtained in as high as 95% yield. On the other hand, benzophenone was found to be a majorproduct under similar conditions, but in the presence of LiCl additive. In this case,benzophenone was obtained in 68% yield.R 2 R 2Br+OR 1 N N R 1NiBr BrZn, THFO+OHR 1 R 2R 1 R 2R 1 R 2The studied catalytic reaction goes readily for more commercially available aryl chlorides aswell. In this case, benzhydrol can be obtained from chlorobenzene and benzaldehyde in ashigh as 90% yield. It should be noted that aryl chlorides gave both benzophenones andbenzhydrols in better yields than similar aryl bromides.This report also describes in details the results of our study of cross-coupling of aryl halideswith aromatic aldehydes bearing different functional groups. In general case, aryl halidesbearing electron-donaiting groups gave the respective diarylcarbinols in higher yields.However, benzhydrols bearing carbonyl, ester or nitryl group can be synthesized in thismanner with yields not exceeding 80%.148