title: Efficient catalysis of Suzuki-Miyaura C-C coupling reactions with palladium(II) complexes of partially hydrolyzed bisimine ligands: a process important in environment context.
abstract: Potentially hexadentante [O(-),N,E:E,N,O(-)] chalcogenated bisimine ligands L1-L3 have been synthesized by reaction of 1,1'-(4,6-dihydroxy-1,3-phenylene)bisethanone with H2N(CH2)2SPh, H2N(CH2)2SePh and H2N(CH2)2TeC6H4-4-OMe respectively. The L1-L3 react with Na2PdCl4 resulting in their partial hydrolysis, which appears to be metal-promoted. Of the two [(CH3)CN(CH2)2EAr] fragments of L1-L3, one is converted to (CH3)CO and H2N(CH2)2EAr eliminated. The hydrolysis products 1-[C(CH3)N(CH2)2SPh]-3-[C(CH3)O]-4,6-[OH]2C6H2 (L1'), 1-[C(CH3)N(CH2)2SePh]-3-[C(CH3)O]-4,6-[OH]2C6H2 (L2') and 1-[C(CH3)N(CH2)2TeC6H4-4-OMe]-3-[C(CH3)O]-4,6-[OH]2C6H2 (L3') have formed complexes [PdCl(L'-H)] (1, 3 and 5). The other product of hydrolysis H2N(CH2)2EAr (L″) reacted with Na2PdCl4 yielding the complexes [PdL"Cl2] (2, 4 and 6). All the complexes (1-6) were found thermally and air stable. Complexes 1, 3 and 5 have been investigated as catalysts for Suzuki-Miyaura CC coupling reactions. The catalytic activities of 1 and 3 which are palladium complexes of S- and Se-containing Schiff base derivatives respectively, were found good for the Suzuki-Miyaura cross-coupling of aryl bromides with phenylboronic acid under mild reaction conditions. The Pd(II) complex (3) of selenated ligand was found active to catalyze the coupling of 2-chlorobenzaldehyde and 3-chlorotoluene. The activity of Te analog was found to be the lowest one as it failed in catalyzing the coupling of electronically deactivated aryl bromides.
authors: Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
authors: Arun
authors: A
authors: Kumar
authors: Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
authors: Gyandshwar Kumar
authors: GK
authors: Rao
authors: Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
authors: Fariha
authors: F
authors: Saleem
authors: Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
authors: Rupesh
authors: R
authors: Kumar
authors: Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India. Electronic address: aksingh@chemistry.iitd.ac.in.
authors: Ajai K
authors: AK
authors: Singh
mesh_terms: D001897:Boronic Acids / Q000737:chemistry; D002384:Catalysis; D018360:Crystallography, X-Ray; D004785:Environmental Pollutants / Q000737:chemistry*; D006868:Hydrolysis; D007097:Imines / Q000737:chemistry*; D007202:Indicators and Reagents; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D010165:Palladium / Q000737:chemistry*; D013055:Spectrophotometry, Infrared
chemical_list: D001897:Boronic Acids; D004785:Environmental Pollutants; D007097:Imines; D007202:Indicators and Reagents; D008024:Ligands; D010165:Palladium; C010686:benzeneboronic acid
keywords: Aryl halides; Catalysis; Chalcognated Schiff base; Ligand; Palladium; Suzuki–Miyaura coupling