62343-68-4Relevant articles and documents
Anodic benzylic C(sp3)-H amination: Unified access to pyrrolidines and piperidines
Herold, Sebastian,Bafaluy, Daniel,Mu?iz, Kilian
, p. 3191 - 3196 (2018/07/29)
An electrochemical aliphatic C-H amination strategy was developed to access the important heterocyclic motifs of pyrrolidines and piperidines within a uniform reaction protocol. The mechanism of this unprecedented C-H amination strategy involves anodic C-H activation to generate a benzylic cation, which is efficiently trapped by a nitrogen nucleophile. The applicability of the process is demonstrated for 40 examples comprising both 5- and 6-membered ring formations.
Influence of Constitution and Charge on Radical Pairing Interactions in Tris-radical Tricationic Complexes
Cheng, Chuyang,Cheng, Tao,Xiao, Hai,Krzyaniak, Matthew D.,Wang, Yuping,McGonigal, Paul R.,Frasconi, Marco,Barnes, Jonathan C.,Fahrenbach, Albert C.,Wasielewski, Michael R.,Goddard, William A.,Stoddart, J. Fraser
supporting information, p. 8288 - 8300 (2016/07/15)
The results of a systematic investigation of trisradical tricationic complexes formed between cyclobis(paraquat-p-phenylene) bisradical dicationic (CBPQT2(?+)) rings and a series of 18 dumbbells, containing centrally located 4,4′-bipyridinium radical cationic (BIPY?+) units within oligomethylene chains terminated for the most part by charged 3,5-dimethylpyridinium (PY+) and/or neutral 3,5-dimethylphenyl (PH) groups, are reported. The complexes were obtained by treating equimolar amounts of the CBPQT4+ ring and the dumbbells containing BIPY2+ units with zinc dust in acetonitrile solutions. Whereas UV-Vis-NIR spectra revealed absorption bands centered on ca. 1100 nm with quite different intensities for the 1:1 complexes depending on the constitutions and charges on the dumbbells, titration experiments showed that the association constants (Ka) for complex formation vary over a wide range, from 800 M-1 for the weakest to 180 000 M-1 for the strongest. While Coulombic repulsions emanating from PY+ groups located at the ends of some of the dumbbells undoubtedly contribute to the destabilization of the trisradical tricationic complexes, solid-state superstructures support the contention that those dumbbells with neutral PH groups at the ends of flexible and appropriately constituted links to the BIPY?+ units stand to gain some additional stabilization from C-H?π interactions between the CBPQT2(?+) rings and the PH termini on the dumbbells. The findings reported in this Article demonstrate how structural changes implemented remotely from the BIPY?+ units influence their non-covalent bonding interactions with CBPQT2(?+) rings. Different secondary effects (Coulombic repulsions versus C-H?π interactions) are uncovered, and their contributions to both binding strengths associated with trisradical interactions and the kinetics of associations and dissociations are discussed at some length, supported by extensive DFT calculations at the M06-D3 level. A fundamental understanding of molecular recognition in radical complexes has relevance when it comes to the design and synthesis of non-equilibrium systems.
An investigation into the tether length and substitution pattern of arene-substituted complexes for asymmetric transfer hydrogenation of ketones
Cheung, Fung K.,Lin, Changxue,Minissi, Franco,Criville, Adriana Lorente,Graham, Mark A.,Fox, David J.,Wills, Martin
, p. 4659 - 4662 (2008/03/12)
(Figure Presented) A series of Ru(II) catalysts were prepared and tested in the asymmetric transfer hydrogenation of ketones. The catalyst containing a "4-carbon" tether gave the fastest rates of ketone reduction. This is due to both increased rate of reg
