13737-04-7Relevant academic research and scientific papers
Synthesis, Characterization, and DFT Analysis of Bis-Terpyridyl-Based Molecular Cobalt Complexes
Aroua, Safwan,Todorova, Tanya K.,Hommes, Paul,Chamoreau, Lise-Marie,Reissig, Hans-Ulrich,Mougel, Victor,Fontecave, Marc
supporting information, p. 5930 - 5940 (2017/05/22)
Terpyridine ligands are widely used in chemistry and material sciences owing to their ability to form stable molecular complexes with a large variety of metal ions. In that context, variations of the substituents on the terpyridine ligand allow modulation of the material properties. Applying the Stille cross-coupling reaction, we prepared with good yields a new series of terpyridine ligands possessing quinoline-type moieties in ortho, meta, and para positions and dimethylamino substituents at central or distal positions. The corresponding cobalt(II) complexes were synthesized and fully characterized by elemental analysis, single-crystal X-ray crystallography, mass spectrometry, and UV-vis, 1H NMR, and Fourier transform infrared (FT-IR) spectroscopy as well as by cyclic voltammetry (CV). Density functional theory (DFT) calculations were performed to investigate the electronic structure of all the Co(II) bis-terpyridyl molecular complexes. In this work, we show that terpyridine ligand functionalization allows tuning the redox potentials of the Co(III)/Co(II), Co(II)/Co(I), and Co(I)/Co(I) (tpy)?- couples over a 1 V range.
Generation and reactions of pyridyllithiums via Br/li exchange reactions using continuous flow microreactor systems
Nagaki, Aiichiro,Yamada, Daisuke,Yamada, Shigeyuki,Doi, Masatomo,Ichinari, Daisuke,Tomida, Yutaka,Takabayashi, Naofumi,Yoshida, Jun-Ichi
, p. 199 - 207 (2013/03/28)
A continuous flow microreactor method for generating and carrying out reactions on pyridyllithiums has been developed based on Br/Li exchange reactions of bromopyridines and dibromopyridines. The reactions can be carried out without using cryogenic conditions by virtue of short residence times and efficient heat transfer, while very low temperatures such as-78 or-110°C are required for conventional batch macro methods. Moreover, sequential introduction of two different electrophiles has been successfully achieved using dibromopyridines in an integrated flow microreactor system composed of four micromixers and four microtube reactors.
Homoleptic zincate-promoted room-temperature halogen-metal exchange of bromopyridines
Chau, Nguyet Trang Thanh,Meyer, Maxime,Komagawa, Shinsuke,Chevallier, Floris,Fort, Yves,Uchiyama, Masanobu,Mongin, Florence,Gros, Philippe C.
experimental part, p. 12425 - 12433 (2011/01/05)
Homoleptic lithium tri- and tetraalkyl zincates were reacted with a set of bromopyridines. Efficient and chemoselective bromine-metal exchanges were realized at room temperature with a substoichiometric amount of nBu 4ZnLi2·TMEDA reagent (1/3 equiv; TMEDA=N,N,N′,N′-tetramethylethylenediamine). This reactivity contrasted with that of tBu4ZnLi2·TMEDA, which was inefficient below one equivalent. DFT calculations allowed us to rationalize the formation of N...Li stabilized polypyridyl zincates in the reaction. The one-pot difunctionalization of dibromopyridines was also realized using the reagent stoichiometrically. The direct creation of C-Zn bonds in bromopyridines enabled us to perform efficient Negishi-type cross-couplings. Mild zincation! nBu4ZnLi2·TMEDA (in substoichiometric amounts) promoted efficient and chemoselective room-temperature bromine-metal exchange of a range of bromopyridines (see scheme). DFT calculations strongly supported the formation of a stabilized tripyridylzincate, which could be reacted with electrophiles or be directly involved in palladium-catalyzed cross-coupling reactions.
Aggregative activation in heterocyclic chemistry. Part 5. Lithiation of pyridine and quinoline with the complex base BuLi·Me2N(CH2)2OLi (BuLi·LiDMAE)
Gros, Philippe,Fort, Yves,Caubere, Paul
, p. 3597 - 3600 (2007/10/03)
It is shown that the complex base BuLi·LiDMAE reacts with pyridine to give metallated species which, after trapping by electrophiles, lead to 2-substituted pyridines in good to excellent yields. The same reactions have been less successfully performed with quinoline.
On the Mechanism of the Carbodesilylation of 4- or 5-Substituted 2-(Trimethylsilyl)pyridines
Effenberger, Franz,Krebs, Andreas,Willrett, Peter
, p. 1131 - 1140 (2007/10/02)
An "ylide mechanism" is proposed for the carbodesilylation of 2-(trimethylsilyl)pyridines with benzaldehyde.In contrast, 3- and 4-(trimethylsilyl)pyridines, react only in the presence of a base catalyst via pyridyl anions with electrophiles.The rates of the uncatalyzed carbodesilylation reactions of 4-substituted 2-(trimethylsilyl)pyridines 2 with benzaldehyde correlate very well with the resonance parameters of the substituents ?0R, whereas the rates of 5-substituted 2-(trimethylsilyl)pyridines 7 correlate with the inductive substituent parameters ?1 in the Taft equation.This is to our knowledge the first direct determination of the resonance parameters ?0R.Key Words: Pyridines, substituted 2-(trimethylsilyl)-, synthesis of, carbodesilylation of / Carbodesilylation / Rate constants
Synthesis and 1H, 13C, 14N, 15N, 29Si NMR study of trimethylsilylquinolines and their methiodides
Lukevics, Edmunds,Liepins, Edvards,Segal, Izolda,Fleisher, Mendel
, p. 283 - 298 (2007/10/02)
2-, 3-, 4-, 5-, 6-, 7-, and 8-trimethylsilylquinolines and their methiodides as well as some 2-silylalkylquinolines were obtained by lithium synthesis in order to elucidate intramolecular donor-acceptor interactions between nitrogen and silicon atoms. 1H, 13C, 14N, 15N and 29Si NMR spectra of the compounds were studied and quantum-chemical calculation of charges on individual atoms in the unsubstituted quinoline and in trimethylsilylquinoline molecule was carried out.The two-centred component of the total system energy for various bonds was calculated.The findings suggest donor-acceptor interaction between nitrogen and silicon atoms in 2-trimethylsilylquinoline that reduces electron density at nitrogen atoms.An apparently weaker interaction is observed in 8-trimethylsilylquinoline.
Functionalization of Pyridine via Direct Metallation
Verbeek, Jacob,George, Albert V. E.,Jong, Robertus L. P. de,Brandsma, Lambert
, p. 257 - 258 (2007/10/02)
The isolation of mixtures of 2-, 3-, and 4-deuteriopyridine, 2-, 3-, and 4-trimethylsilylpyridine, or 2-, 3-, and 4-methylthiopyridine indicates successful metallation of pyridine with a 1:1 mixture of BuLi-ButOK in tetrahydrofuran-hexane at -100 deg C.
