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Current Organic Synthesis


ISSN (Print): 1570-1794
ISSN (Online): 1875-6271

Research Article

In situ Generation of Efficient Palladium N-heterocyclic Carbene Catalysts Using Benzimidazolium Salts for the Suzuki-Miyaura Cross-coupling Reaction

Author(s): Senem Akkoç, Yetkin Gök, lhan Özer lhan and Veysel Kayser

Volume 13 , Issue 5 , 2016

Page: [761 - 766] Pages: 6

DOI: 10.2174/1570179413666151218200334

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Five new unsymmetrically substituted salts containing a benzimidazole backbone were synthesized in high yields and their structures were verified via spectroscopic and analytical methods such as HRMS, 1D and 2D NMR spectroscopy, FT-IR and elemental analysis. The catalytic properties of all the synthesized salts were tested in a homogeneous Suzuki-Miyaura cross-coupling reaction to get coupling products in high efficiencies with low amounts of in situ formed catalysts. In this reaction, the couplings of boronic acid derivatives with different aryl chlorides were made in the presence of palladium acetate, 2-6 and base at various times and temperatures. According to the obtained results, the benzimidazolium salts which are N-heterocyclic carbene (NHC) ligand precursors were found to have high catalytic activity. In particular, the coupling of 4-chlorotoluene with phenylboronic acid was obtained in very high yield and conversion in the catalyzed Pd-NHC complexes which were in situ formed from compounds 3 and 6 and Pd(OAc)2.

Keywords: Synthesis, Catalysis, N-Heterocyclic carbene precursors, Benzimidazolium salts, Suzuki-Miyaura cross-coupling reaction.

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