Two new chromium(III) complexes, [Cr(4,4′-X2bpdo)3]3+ (X = MeO or EtO; bpdo = 2,2′–bipyridine1,1′-dioxide), were prepared. These complexes form two diastereomers, lel3(Δ(λλλ), Λ(δδδ)) and lel2ob(Δ(λλδ), Λ(δδλ)), which were separated and resolved by an SP-Sephadex column chromatographic method using achiral eluting agents, such as Na2SO4 or NaCl. The isomers isomerized to each other (lel3 lel2ob) fairly
Catalytic Conversions in Water. Part 22: Electronic Effects in the (Diimine)palladium(II)-Catalysed Aerobic Oxidation of Alcohols
作者:Gerd-Jan ten Brink、Isabel W. C. E. Arends、Marcel Hoogenraad、Göran Verspui、Roger A. Sheldon
DOI:10.1002/adsc.200390057
日期:2003.4
The electroniceffects in the (diimine)Pd(II)-catalysedaerobicoxidation of alcohols were investigated from the viewpoint of both the catalyst and the alcohol. A ‘push–pull' mechanism is operative, where both electron-donating substituents on the benzyl alcohol (ρ=−0.58) and electron-withdrawing groups on the 4,4′-disubstituted-2,2′-bipyridine ligand (ρ=+0.18) increase the reaction rate. The results
Conformational inversion of 2,2′-bipyridine 1,1′-dioxide chelate ring in a series of (2,2′,2′′-triaminotriethylamine)(4,4′-disubstituted-2,2′-bipyridine 1,1′-dioxide)cobalt(III) complexes
Abstract A new series of cobalt(III) complexes, [Co(2,2′,2′′-triaminotriethylamine)(4,4′-X 2 bpdo)] 3+ (X=Me, MeO, EtO), where 4,4′-X 2 bpdo denotes 4,4′-disubstituted-2,2′-bipyridine1,1′-dioxide, were prepared. The complexes were resolved into a pair of enantiomers (conformational optical isomers), and gradually racemized in water by conformational inversion of the skewed 4,4′-X 2 bpdo chelate ring
Modular preparation of cationic bipyridines and azaarenes <i>via</i> C–H activation
作者:Ryan P. King、Jenny Y. Yang
DOI:10.1039/d3sc04864k
日期:——
preparation of trimethylammonium- and triarylphosphonium-substituted bipyridines and azaheterocycles is disclosed. This methodology showcases a C–H activation of pyridine N-oxides that enables a highly modular and scalable synthesis of a diverse array of cationically charged azaarenes. The addition of trimethylammonium functionalities on bipyridine derivatives resulted in more anodic reduction potentials (up
Boronium complexes bearing a 9-borabicyclononane framework with a bipyridine-type ligand display photoinduced solid-state coloring behavior. While the identity of the substituents on the boron atom is critical to gain photoresponsive capability, modifying the nitrogen-containing ligand structure and its substituents provides a wide variation in the photoinduced solid color. (C) 2016 Elsevier Ltd. All rights reserved.