Sonogashira Coupling (Cu/Amine‐Free) of ArBr/Cl in Aerobic Condition and N<i>‐</i>Benzylation of Aniline with Benzyl Alcohol Catalyzed by Complexes of Pd(II) with Sulfated/Selenated NHCs

Dubey, P. K.; Singh, Anurag

doi:10.1002/slct.201904819

Cited by 11 publications

(34 citation statements)

References 186 publications

(27 reference statements)

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“…In this scenario, one palladium precatalyst activates the (het)aryl halide and another activates the terminal alkyne. This mechanistic proposal places the copper-free Sonogashira reaction (Heck-Cassar alkynylation) among bimetallic catalytic reactions in which the same metal serves two distinct functions [33][34][35] . To our knowledge, there have been very few reports postulating this type of catalysis, all based on the palladium-palladium system [36][37][38][39] , i.e., the arylation of pyridine N-oxide with aryl bromides 36 , the cyanation of aryl bromides with HCN 37 , the aerobic oxidative coupling of arenes 38 , and the carbonylative Sonogashira cross-coupling 39 .…”

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confidence: 99%

Elucidating the reaction mechanism of a palladium-palladium dual catalytic process through kinetic studies of proposed elementary steps

2023

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In the synergistic dual catalytic process, the kinetics of the catalytic cycles must be balanced for the successful outcome of the reaction. Therefore, the analysis of the kinetics of the independent catalytic cycles is essential for such reactions, as it enables their relational optimization as well as their design. Here we describe an analysis of the mechanism of a catalytic synergistic bimetallic reaction through the experimental study of a palladium-catalysed cross-coupling of aryl halides with terminal alkynes, an example of a monometallic dual catalytic process. The proposed mechanism of the investigated reaction was disassembled into two palladium catalytic cycles and further into elementary reactions, and each step was studied independently. The described mechanistic analysis allowed us to identify the rate-determining step of the catalytic process by comparing the rates of the elementary reactions under similar reaction conditions, balanced kinetics of the palladium catalytic cycles, and also in which step which reagent enters the catalytic cycle and how.

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confidence: 99%

Elucidating the reaction mechanism of a palladium-palladium dual catalytic process through kinetic studies of proposed elementary steps

2023

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“…The synthetic scheme for the preparation of benzimidazolium salts is presented in Scheme 2. The benzimidazolium salts were synthesized by slightly modifying the procedures from the literature [25][26][27][28][29]. In more detail, benzimidazole was initially reacted with 1,2-dibromoethane in acetonitrile in the presence of K 2 CO 3 .…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Selenium-Based Small Molecules Inspired by CNS-Targeting Psychotropic Drugs and Mediators

et al. 2023

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Due to its endogenously high oxygen consumption, the central nervous system (CNS) is vulnerable to oxidative stress conditions. Notably, the activity of several CNS-targeting compounds, such as antidepressant and hypnotic drugs, or endogenous mediators, such as melatonin, is indeed linked to their ability of mitigating oxidative stress. In this work, we report the synthesis of two organoselenium compounds of which the structure was inspired by CNS-targeting psychotropic drugs (zolpidem and fluoxetine) and an endogenous mediator (melatonin). The molecules were designed with the aim of combining the ROS-scavenging properties, which were already assessed for the parent compounds, with a secondary antioxidant action, a glutathione peroxidase (GPx) mimic role empowered by the presence of selenium. The compounds were obtained through a facile three-step synthesis and were predicted by computational tools to passively permeate through the blood–brain barrier and to efficiently bind to the GABA A receptor, the macromolecular target of zolpidem. Of note, the designed synthetic pathway enables the production of several other derivatives through minor modifications of the scheme, paving the way for structure–activity relationship studies.

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“…Contrary to a previous belief, it has been recently postulated by us , and others that the mechanism of copper-free alkynylation operates through a process that resembles copper cocatalyzed variant, but the role of copper is played by palladium (Scheme ). It builds on transmetalation (TM) between two distinct palladium species, oxidative addition (OA) intermediate A that is generated within Pd1-Cycle , and acetylide B from the Pd2-Cycle .…”

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confidence: 84%

Designing Homogeneous Copper-Free Sonogashira Reaction through a Prism of Pd–Pd Transmetalation

et al. 2020

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Simultaneous introduction of two different palladium (pre)catalysts, one tuned to promote oxidative addition to (hetero)aryl bromide and another to activate terminal alkyne substrate, leads to productive Pd−Pd transmetalation, subsequent reductive elimination, and formation of disubstituted alkyne. This conceptually novel rational design of copper-free Sonogashira reaction enabled facile identification of the reaction conditions, suitable for the synthesis of alkyl, aryl, and heteroaryl substituted alkynes at room temperature with as low as 0.125 mol % total Pd loading.

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Sonogashira Coupling (Cu/Amine‐Free) of ArBr/Cl in Aerobic Condition and N‐Benzylation of Aniline with Benzyl Alcohol Catalyzed by Complexes of Pd(II) with Sulfated/Selenated NHCs

Cited by 11 publications

References 186 publications

Elucidating the reaction mechanism of a palladium-palladium dual catalytic process through kinetic studies of proposed elementary steps

Elucidating the reaction mechanism of a palladium-palladium dual catalytic process through kinetic studies of proposed elementary steps

Synthesis of Selenium-Based Small Molecules Inspired by CNS-Targeting Psychotropic Drugs and Mediators

Designing Homogeneous Copper-Free Sonogashira Reaction through a Prism of Pd–Pd Transmetalation

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