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ИСТИНА ЦЭМИ РАН |
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Due to a great need to replace expensive palladium for much cheaper copper in the catalysis of C-N bonds formation a thorough investigation was carried out to explore the possibilities and limitations of the catalysts of both types in the synthesis of N,N’-di(hetero)aryl derivatives of polyoxadiamines. Three oxadiamines were used as starting compounds which differ by the number of oxygen atoms and methylene groups between nitrogen and oxygen atoms. As aryl halides substituted bromo- and iodobenzenes were tested containing the following substituents: F, CF3, CN, Ph, COMe, COPh, COOEt, OMe. To conduct the heteroarylation reactions, 2-bromo-, 2-iodo- and 3-iodopyridines were applied. As catalytic systems Pd(dba)2/BINAP and Pd(dba)2/DavePhos were used in Pd series, CuI/2-isobutyrylcyclohexanone and CuI/BINOL were taken in Cu series. In many cases the possibility of successful synthesis of the target compounds was demonstrated using both Pd(0)- and Cu(I)-catalyzed approaches, excluding the amination of ortho-substituted halogenobenzenes. In this case Pd catalysis was found to be much more efficient.