64909-91-7Relevant academic research and scientific papers
Mechanistic Aspects of Pincer Nickel(II)-Catalyzed C-H Bond Alkylation of Azoles with Alkyl Halides
Patel, Ulhas N.,Jain, Shailja,Pandey, Dilip K.,Gonnade, Rajesh G.,Vanka, Kumar,Punji, Benudhar
, p. 1017 - 1025 (2018)
The quinolinyl-based pincer nickel complex, κN,κN,κN-{C9H6N-(μ-N)-C6H4-NMe2}NiCl [(QNNNMe2)NiCl; (1)] has recently been demonstrated to be an efficient and robust catalyst for the alkylation of azoles with alkyl halides under copper-free conditions. Herein, we report the detailed mechanistic investigation for the alkylation of azoles catalyzed by (QNNNMe2)NiCl (1), which highlights an iodine-atom transfer (IAT) mechanism for the reaction involving a NiII/NiIII process. Deuterium labeling experiments indicate reversible cleavage of the benzothiazole C-H bond, and kinetic studies underline a fractional negative rate order with the substrate benzothiazole. The involvement of an alkyl radical during the alkylation is validated by radical clock and external additive experiments. An active intermediate species (QNNNMe2)Ni(benzothiazolyl) (5a) has been isolated and structurally characterized. The complex (QNNNMe2)Ni(benzothiazolyl) (5a) is found to be the resting state of catalyst 1. Kinetic analysis of electronically different intermediates suggests that the step involving the reaction of 5a with alkyl iodide is crucial and a rate-influencing step. DFT calculations strongly support the experimental findings and corroborate an IAT process for the alkylation reaction.
Photoelectrochemical cross-dehydrogenative coupling of benzothiazoles with strong aliphatic C-H bonds
Capaldo, Luca,Quadri, Lorenzo L.,Merli, Daniele,Ravelli, Davide
, p. 4424 - 4427 (2021/05/10)
A photoelectrochemical strategy for the cross-dehydrogenative coupling of unactivated aliphatic hydrogen donors (e.g.alkanes) with benzothiazoles is reported. We used tetrabutylammonium decatungstate as the photocatalyst to activate strong C(sp3)-H bonds in the chosen substrates, while electrochemistry scavenged the extra electrons.
Unexpected Ring Opening During the Imination of Camphor-Type Bicyclic Ketones
Chernyshov, Vladimir V.,Yarovaya, Olga I.,Vatsadze, Sergey Z.,Borisevich, Sophia S.,Trukhan, Sergey N.,Gatilov, Yuri V.,Peshkov, Roman Yu.,Eltsov, Ilia V.,Martyanov, Oleg N.,Salakhutdinov, Nariman F.
, p. 452 - 463 (2020/12/18)
A new ring opening reaction was found while attempting to isolate the imines from ortho-heteroatom substituted anilines and camphor-like bicyclic ketones. The benzoazoles containing a cyclopentanemethyl group at position 2 of the heterocycle were isolated instead of the expected imines. The detailed study of the transformation, including EPR experiments, revealed the most probable radical mechanism. The proposed reaction pathways were confirmed by quantum chemical calculations. The dichotomy of 1–2 and 2–3 bonds cleavage is discussed together with the evaluation of the stereochemical outcome of the reactions. The benzoazoles obtained via the new reaction are of particular interest for the medicinal chemistry.
Ni-Catalyzed Reductive Liebeskind-Srogl Alkylation of Heterocycles
Ma, Yuanhong,Cammarata, Jose,Cornella, Josep
supporting information, p. 1918 - 1922 (2019/02/14)
Herein we present a Ni-catalyzed alkylation of C-SMe with alkyl bromides for the decoration of heterocyclic frameworks. The protocol, reminiscent to the Liebeskind-Srogl coupling, makes use of simple C(sp2)-SMe to be engaged in a reductive coupling. The reaction is suitable for a preponderance of highly valuable heterocyclic motifs. In addition to cyclic bromides, noncyclic alkyl bromides are well accommodated with exquisite levels of retention over isomerization. The protocol is scalable and permits orthogonal couplings in the presence of other functionalization handles.
Palladium- and nickel-catalyzed direct alkylation of azoles with unactivated alkyl bromides and chlorides
Yao, Tomoyuki,Hirano, Koji,Satoh, Tetsuya,Miura, Masahiro
scheme or table, p. 12307 - 12311 (2011/02/16)
Long-ing alkyl chain: The catalytic direct C-H alkylation of azoles with unactivated alkyl bromides and chlorides is described. A palladium catalyst enables the alkylation of oxazoles, whereas a nickel one shows unique activity for thiazole. The catalyses allow a straightforward access to azole motifs bearing long, functional alkyl side chains.
