Deoxygenation of tertiary amine N-oxides under metal free condition using phenylboronic acid

A simple and efficient method for the deoxygenation of amine N-oxides to corresponding amines is reported using the green and economical reagent phenylboronic acid. Deoxygenation of N,N-dialkylaniline N-oxides, trialkylamine N-oxides and pyridine N-oxides were achieved in good to excellent yields. The reduction susceptible functional groups such as ketone, amide, ester and nitro groups are well tolerated with phenylboronic acid during the deoxygenation process even at high temperature. In addition, an indirect method for identification and quantification of tert-amine N-oxide is demonstrated using UV–Vis spectrometry which may be useful for drug metabolism studies.     

A Neutral Four-Coordinate Mononuclear Cobalt(II) Complex with Biphenyl Appended N-Bidendate Ligand: Synthesis, Structure and Spectral Properties

Abstract  

A mononuclear cobalt(II) complex [Co(BP)(Cl₂)], 1 with a new N,N-bidentate ligand, BP ([N,N-(1,1′-biphenyl-2,2′-dimethylene)]-2-aminomethyl) pyridine) was synthesized and characterized by elemental analysis, UV–Vis, paramagnetic NMR, magnetic moment and single crystal XRD. The air and moisture stable Co(II) title complex is a 15 electron species which crystallizes in the monoclinic space group P2₁/n with cell dimensions a = 10.406(3), b = 12.873(4), c = 13.859(7) ?, β = 96.30(3)˚ and Z = 4. The cobalt atom has distorted tetrahedral (td) geometry with coordination provided by an amine and pyridyl nitrogen donors of BP and two terminal chloride ions. The packing is stabilized through C–H···π and van der Waals interactions.     

Synthesis,structure, and characterization of picolyl- and benzyl-linked biphenyl palladium N-heterocyclic carbene complexes and their catalytic activity in acylative cross-coupling reactions

N-heterocyclic carbene ligands with picolyl (L¹H₂Br₂, L³H₂Br₂) and benzyl (L²H₂Br₂, L⁴H₂Br₂) linked biphenyl backbone were synthesized and characterized. Their palladium(II) complexes [PdL¹]Br₂ ( 1 ), [PdL²Br₂] ( 2 ), [PdL³]Br₂ ( 3 ), and [PdL⁴Br₂] ( 4 ) were synthesized by direct method using Pd(OAc)₂. All complexes ( 1 – 4 ) were characterized by CHN analysis, electrospray ionization-MS, nuclear magnetic resonance, and single-crystal X-ray diffraction. Molecular structures confirm the distorted square planar geometry around the Pd(II) center. All of them showed good catalytic activity in acylative Suzuki cross coupling of phenyl boronic acid with benzoyl chloride to afford benzophenone in good yields.     

Structure of a five-coordinate mononuclear cobalt(II) complex: chlorobis([N,N-(1,1′-biphenyl-2,2′-dimethylene)]-2-aminomethyl) pyridine)cobalt(II) bromide

A penta-coordinate mononuclear cobalt(II) complex, [Co(BP)₂(Cl⁻)](Br⁻), 1 with a novel, biphenyl-appended N,N-bidentate ligand, BP ([N,N-(1,1′-biphenyl-2,2′-dimethylene)]-2-aminomethyl) pyridine) was synthesized and characterized by elemental analysis, UV-Vis, electro-spray ionization mass spectrum and single crystal XRD. The title complex crystallizes in the monoclinic space group C2/c with cell dimensions a = 11.389(2), b = 25.627(3), c = 12.276(3) Å, β = 100.419(18)° and Z = 2. The cobalt atom has a distorted trigonal bipyramidal (tbp) geometry and is surrounded by 4Ns of two BP, and a Cl⁻/Br⁻ at the 5th coordination site. This is the first report of a mononuclear tbp cobalt complex with biphenyl appended bidentate ligand containing amino-pyridyl moiety.