Добірка наукової літератури з теми "Copper Photoredox catalysis"

Photoredox catalysis has been applied to renewable energy and green chemistry for many years. Ruthenium and iridium, which can be used as photoredox catalysts, are expensive and scarce in nature. Thus, the further development of catalysts based on these transition metals is discouraged. Alternative photocatalysts based on copper complexes are widely investigated, because they are abundant and less expensive. This review discusses the scope and application of photoinduced copper-based catalysis along with recent progress in this field. The special features and mechanisms of copper photocatalysis and highlights of the applications of the copper complexes to photocatalysis are reported. Copper-photocatalyzed reactions, including alkene and alkyne functionalization, organic halide functionalization, and alkyl C–H functionalization that have been reported over the past 5 years, are included.

The use of copper catalysis with visible light photoredox catalysis in a cooperative fashion has recently emerged as a versatile means of developing new C–C bond forming reactions. In this work, dual copper and photoredox catalysis is exploited to effect C(sp²)–C(sp³) cross-couplings between aryl boronic acids and benzyl bromides.

This report describes a highly enantioselective oxidative sp3 C–H arylation of N-aryltetrahydroisoquinolines (THIQs) through a dual catalysis platform. The combination of the photoredox catalyst, [Ir(ppy)2(dtbbpy)]PF6, and chiral copper catalysts provide a mild and highly effective sp3 C–H asymmetric arylation of THIQs.

Visible-light photoredox catalysis offers a distinct activation mode complementary to thermal transition metal catalyzed reactions. The vast majority of photoredox processes capitalizes on precious metal ruthenium(II) or iridium(III) complexes that serve as single-electron reductants or oxidants in their photoexcited states. As a low-cost alternative, organic dyes are also frequently used but in general suffer from lower photostability. Copper-based photocatalysts are rapidly emerging, offering not only economic and ecological advantages but also otherwise inaccessible inner-sphere mechanisms, which have been successfully applied to challenging transformations. Moreover, the combination of conventional photocatalysts with copper(I) or copper(II) salts has emerged as an efficient dual catalytic system for cross-coupling reactions.

Metallaphotoredox catalysis for furan synthesis: The cyclisation of yne-enones proceeds smoothly via consecutive reductive radical-polar crossover and cycloisomerization processes enabled by cooperative photoredox-neutral and copper catalysis.

Transition metal–catalyzed arene functionalization has been widely used for molecular synthesis over the past century. In this arena, copper catalysis has long been considered a privileged platform due to the propensity of high-valent copper to undergo reductive elimination with a wide variety of coupling fragments. However, the sluggish nature of oxidative addition has limited copper’s capacity to broadly facilitate haloarene coupling protocols. Here, we demonstrate that this copper oxidative addition problem can be overcome with an aryl radical–capture mechanism, wherein the aryl radical is generated through a silyl radical halogen abstraction. This strategy was applied to a general trifluoromethylation of aryl bromides through dual copper-photoredox catalysis. Mechanistic studies support the formation of an open-shell aryl species.

L’atome de fluor joue un rôle crucial dans la modulation des propriétés physico-chimiques des molécules organiques. Son incorporation au sein de la structure des médicaments a connu une expansion rapide et importante. En raison de sa forte électronégativité et de sa lipophilie, le motif trifluorométhyle est couramment employé par l’industrie pharmaceutique. De plus, parmi les composés fluorés, les alcènes substitués par du fluor sont également d’une grande importance en chimie médicinale. Dans ce contexte, nous nous sommes intéressés au développement de voies de synthèses pour incorporer des motifs trifluorométhyles et alcènes monofluorés au sein de molécules. Dans un premier temps, nous avons développé une méthode de chlorotrifluorométhylation d’alcènes internes, médiée par la lumière visible et catalysée par un catalyseur photoredox à base de cuivre. La réaction s’est déroulée avec une régiosélectivité totale dans des conditions de réaction douces en utilisant le CF3SO2Cl disponible dans le commerce comme source de trifluorométhyle et de chlore, conduisant à une synthèse de produits chimiques à haute valeur ajoutée avec une économie d'atomes. Les molécules obtenues ont été testés in vitro pour évaluer leurs cytotoxicités contre les lignées cellulaires cancéreuses ainsi que pour leurs activités antifongiques et antibactériennes. Dans un second temps, une synthèse sans solvant a été développée par mécanochimie afin d’accéder à des monofluoroalcènes. La réaction en une étape est très rapide, sans solvant et se déroule dans des conditions douces permettant de limiter l’impact environnemental de synthèse. Le protocole a montré une efficacité et une tolérance générales à un large panel de substrats carbonylés, y compris les aldéhydes et les cétones, et des dérivés de fluorophosphonoacétate.La douleur chronique touche 20 à 30% de la population mondiale et représente des milliards de dollars en coût annuel. Elle représente un véritable enjeu de santé publique rendant essentiel la poursuite des recherches scientifiques dans ce domaine afin de mieux comprendre la douleur chronique et de développer des solutions innovantes pour améliorer la qualité de vie des patients. Les peptides sont des cibles de choix dans la synthèse de nouveaux médicaments. Le peptide neurotensine (8-13) a démontré son efficacité dans le traitement de la douleur, par modulation des signaux nociceptifs, en se liant aux récepteurs neurotensinergiques, principalement NTS1 et NTS2. Néanmoins, la liaison au récepteur NTS1 provoque des effets secondaires néfastes, ce qui n’est pas le cas lors de la liaison à NTS2. Ainsi, une grande sélectivité envers le récepteur NTS2 est essentielle. Cependant, la forte sélectivité du peptide NT(8-13) envers le récepteur NTS1 ne fait pas de ce peptide un composé de choix dans le cas du traitement de la douleur. Ainsi, synthétiser des analogues peptidiques capables d'interagir de manière sélective avec NTS2, dans l'objectif d'améliorer leur efficacité et leur profil pharmacologique tout en minimisant les effets secondaires, représente un défi de choix. Dans ce contexte, ce dernier chapitre décrit la synthèse de composés capables de se lier aux récepteurs neurotensinergiques tout en maximisant la sélectivité envers NTS2. Pour cela, la synthèse peptidique de JMV 7323, JMV 7324, JMV 7325 et JMV 7326 sur support solide a été effectuée. De plus, les peptides obtenus doivent être capable de passer la barrière hémato-encéphalique. Pour cela, le peptide angiopep-2 a été couplé sur le peptide JMV 7324 pour être utilisé comme navette afin d’atteindre la barrière hémato-encéphalique. Les composés ont été testés in vivo dans des modèles de douleur induite par la formaline montrant des résultats prometteurs et les effets secondaires ont été étudiés
The fluorine atom plays a crucial role in modulating the physicochemical properties of organic molecules. Its incorporation into the structure of drugs has expanded rapidly and significantly. Due to its strong electronegativity and lipophilicity, the trifluoromethyl moiety is commonly used by the pharmaceutical industry. In addition, among fluorinated compounds, monofluoroalkenes are also of great importance in medicinal chemistry. In this context, we were interested in the development of synthetic pathways to incorporate trifluoromethyl and monofluoroalkene moieties into molecules. In a first project, we developed a method of chlorotrifluoromethylation of internal alkenes, mediated by visible light and catalyzed by a copper-based photoredox catalyst. The reaction took place with full regioselectivity under mild reaction conditions using commercially available CF3SO2Cl as the source of trifluoromethyl and chlorine, leading to a synthesis of value-added chemicals with atom economy. The molecules obtained were tested in vitro to evaluate their cytotoxicity against cancer cell lines as well as for their antifungal and antibacterial activities. In a second project, a solvent-free synthesis was developed by mechanochemistry to access monofluoroalkenes. The very fast, solvent-free one-step reaction under mild conditions has limited the environmental impact of synthesis. The protocol showed general efficacy and tolerance to a wide range of carbonyl substrates, including aldehydes and ketones, and fluorophosphonoacetate derivatives.Chronic pain affects 20 to 30% of the world's population and represents billions of dollars in annual costs. It represents a real public health issue that makes it essential to continue scientific research in this field to better understand chronic pain and develop innovative solutions to improve the quality of life of patients. Peptides are prime targets in the synthesis of new drugs. The neurotensin peptide (8-13) has demonstrated its efficacy in the treatment of pain, by modulating nociceptive signals, by binding to neurotensinergic receptors, mainly NTS1 and NTS2. Nevertheless, binding to the NTS1 receptor causes harmful side effects, which is not the case when binding to NTS2. Thus, a high selectivity towards the NTS2 receiver is essential. However, the high selectivity of the NT(8-13) peptide towards the NTS1 receptor does not make this peptide a compound of choice for pain treatment. Thus, synthesizing peptide analogues capable of selectively interacting with NTS2, with the aim of improving their efficacy and pharmacological profile while minimizing side effects, represents a challenge of choice. In this context, this chapter describes the synthesis of compounds capable of binding to neurotensinergic receptors while maximizing selectivity towards NTS2. For this, peptide synthesis of JMV 7323, JMV 7324, JMV 7325 and JMV 7326 on solid support was performed. In addition, the resulting peptides must be able to cross the blood-brain barrier. For this, the angiopep-2 peptide was coupled to the JMV 7324 peptide to be used as a shuttle to reach the blood-brain barrier. The compounds were tested in vivo in models of formalin-induced pain showing promising results and side effects were studied

Ces dernières années, la photopolymérisation a fait l'objet d'intenses efforts de recherche en raison de la croissance constante des applications industrielles. C’est un processus rapide pouvant être réalisée à température ambiante, sans solvant et permettant d'obtenir un contrôle spatial et temporel de la polymérisation. Ces dernières années, l'utilisation de conditions d'irradiation douce qui constitue une alternative aux procédés de photopolymérisation UV à l'origine de nombreux soucis de sécurité est activement recherchée. Par conséquent, le développement de nouveaux systèmes photoamorceurs absorbant fortement dans la région visible ou du proche infra-rouge sont activement recherchés par les communautés académiques et industrielles. Néanmoins, même si certains résultats sont prometteurs, les systèmes reportés sont souvent caractérisés par des réactivités modérées et rivalisent difficilement avec les systèmes UV actuels. Dans ce contexte, nous avons synthétisé une large librairie de molécules photosensibles capables d’absorber la lumière dans le domaine du visible ou du proche infrarouge et capables d’amorcer une réaction de polymérisation avec un système photoamorceur basée sur la catalyse photoredox. Dans ce manuscrit, nous présentons aussi bien la synthèse et les capacités de polymérisation de différentes familles de colorants. Leurs propriétés photochimiques ont également été étudiées par spectrométrie UV-visible, luminescence, photolyse, surveillance de la température et expériences de résonance paramagnétique électronique. Des applications telles que l'impression 3D et les expériences d'écriture laser sont également présentées
In recent years, photopolymerization has been the subject of intense research efforts due to the constant growth of industrial applications. It is a quick process that can be performed at room temperature, solvent-free conditions and enables to get a spatial and a temporal control of the polymerization process. In recent years, the use of irradiation conditions that constitutes an alternative to the UV photopolymerization processes at the origin of numerous safety concerns are actively researched. Therefore, the development of new photoinitiating systems which absorb strongly in the visible or near infrared region are actively researched by both the academic and industrial communities. Nevertheless, even if some results are promising, the reported systems are often characterized by moderate reactivities and hardly compete with current UV systems. In this context, we have synthesized a large library of photosensitive molecules capable of absorbing light in the visible or near infrared range and capable of initiating a polymerization reaction with a photoinitiating system based on photoredox catalysis. In this manuscript, we present both the synthesis and the polymerization abilities of different families of dyes. Their photochemical properties were also studied by UV-Visible spectrometry, luminescence, photolysis, temperature monitoring and electronic paramagnetic resonance experiments. Applications such as 3D printing and laser write experiments are also presented

Recently, research concerning photoredox catalysis has enjoyed renewed interest. Photoredox catalysis provides a mode of small molecule activation that takes advantage of the ability of several transition metal complexes to absorb visible light which facilitates single electron transfer (SET) processes with organic substrates. This mild approach has broad applicability across a vast range of chemical transformations. While ruthenium- and iridium-based photoredox-catalysed transformations have received considerable attention, copper-based complexes remain underexplored in this area. This thesis reports on the development of new synthetic methodology with the broad objective of exploring the scope, limitations, and reactivity of copper-based complexes in photoredox catalysis. In particular, the preparation and study of a library of novel and previously reported copper complexes was conducted. This involved an investigation into the synthesis of homoleptic bis(phenanthroline)copper(I) complexes and heteroleptic phenanthroline-containing copper(I) complexes. Extensive characterisation of their structural, photophysical and electrochemical properties was conducted. Both direct and indirect methods were utilised to characterise the fundamental properties of these complexes including an examination of their reactivity in distinctive atom-transfer radical addition (ATRA) processes. The development of new synthetic methodology began with a proof of concept study in which the weak oxidising power of the prototypical copper-based photoredox catalyst, [Cu(dap)\(_2\)]Cl, was utilised to catalyse Povarov-type reactions of N,N dialkylanilines/ N-aryltetrahydroisoquinolines with electron deficient olefins to produce a range of annulated products. This transformation represents the first example of the weak oxidising power of a copper-based photoredox catalyst being exploited to facilitate the oxidation of amines that are ultimately incorporated into synthetic targets. Intriguingly, the presence of trifluoroacetic acid (TFA) in the reaction was found to be essential to facilitate an efficient reaction. An investigation into the role of TFA suggested that the aerobic quenching of putative photoexcited copper(I) species is mediated by TFA. A copper photoredox catalysed dual α-amino C–H/ C–F bond functionalisation reaction was subsequently developed to enable the synthesis of a library of perfluorinated aromatic compounds. During the development of this protocol it was found that a pulsed irradiation strategy provided enhanced yields and significant rate increases when compared to continuous irradiation. This methodology allows for the rapid synthesis of a broad range of fluorinated arenes under mild conditions. This is the first study identifying the potential of pulsed irradiation in photoredox-catalysis.

Cette thèse présente une nouvelle méthode pour accomplir la réaction de Mallory en utilisant la lumière visible. Pour atteindre ce but, la chimie photorédox qui s'est développée ces dernières années permettra une utilisation efficace de la lumière visible. De plus, la chimie en flux continu sera utilisé afin d'augmenter la surface irradiée du mélange réactionnel. Au cours de ces travaux, une nouvelle méthodologie photochimique utilisant un photocatalyseur de cuivre avec la lumière visible a été efficace pour la synthèse du 5hélicène. Un mécanisme de désactivation oxydante est proposé pour cette réaction. Par ailleurs, cette nouvelle méthodologie a été utilisée pour la synthèse d'un dérivé du 5hélicène et d'un 4hélicène-pyrène hybride. Par la suite, la méthodologie photochimique utilisant un photocatalyseur de cuivre avec la lumière visible a servi à la synthèse de divers carbazoles substitués au niveau de l'azote par des groupements aryles et alkyles. Au cours de cette synthèse, la réaction a révélé un problème de régiosélectivité. Ce dernier a été étudié par la synthèse de nouvelles triarylamines. Finalement, il a été découvert que l'utilisation d'un photocatalyseur de fer peut remplacer le photocatalyseur de cuivre en utilisant l'oxygène comme oxydant pour la synthèse de 9-phénylcarbazole.
This thesis presents a new method to perform the Mallory reaction by using visible light. To achieve this goal, photoredox chemistry which has emerged recently, was used to effect efficient use of visible light. Moreover, continuous flow chemistry was used to increase the irradiated reaction mixture surface. During this work, a new photochemical method using a copper photocatalyst and visible light proved efficient for the synthesis of 5helicene. An oxidative quenching mechanism was proposed for this transformation. Also, this new method was used for the synthesis of a 5helicene derivative and a 4helicene-pyrene hybrid. The photochemical method featuring a copper photocatalyst with visible light was used next for the synthesis of various carbazoles substituted by alkyl and aryl groups at the nitrogen position. During this synthesis, the reaction exhibited a regioselective issue that was further studied in the synthesis of new triarylamines. Finally, it was discovered that an iron photocatalyst can replace the copper photocatalyst by using oxygen as the oxidant in the synthesis of 9-phenylcarbazole.

Christine L. Willis and Varinder K. Aggarwal at the University of Bristol have developed (Angew. Chem. Int. Ed. 2012, 51, 12444) a procedure for the diastereodivergent synthesis of trisubstituted alkenes via the protodeboronation of allylic boronates, such as in the conversion of 1 to either 2 or 3. An alternative approach to the stereoselective synthesis of trisubstituted alkenes involving the reduction of the allylic C–O bond of cyclic allylic ethers (e.g., 4 to 5) was reported (Chem. Commun. 2012, 48, 7844) by Jon T. Njardarson at the University of Arizona. A novel synthesis of allylamines was developed (J. Am. Chem. Soc. 2012, 134, 20613) by Hanmin Huang at the Chinese Academy of Sciences with the Pd(II)-catalyzed vinylation of styrenes with aminals (e.g. 6 + 7 to 8). Eun Jin Cho at Hanyang University showed (J. Org. Chem. 2012, 77, 11383) that alkenes such as 9 could be trifluoromethylated with iodotrifluoromethane under visible light photoredox catalysis. David A. Nicewicz at the University of North Carolina at Chapel Hill developed (J. Am. Chem. Soc. 2012, 134, 18577) a photoredox procedure for the anti-Markovnikov hydroetherification of alkenols such as 11, using the acridinium salt 12 in the presence of phenylmalononitrile (13). A unique example of “catalysis through temporary intramolecularity” was reported (J. Am. Chem. Soc. 2012, 134, 16571) by André M. Beauchemin at the University of Ottawa with the formaldehyde-catalyzed Cope-type hydroamination of allyl amine 15 to produce the diamine 16. A free radical hydrofluorination of unactivated alkenes, including those bearing complex functionality such as 17, was developed (J. Am. Chem. Soc. 2012, 134, 13588) by Dale L. Boger at Scripps, La Jolla. Jennifer M. Schomaker at the University of Wisconsin at Madison reported (J. Am. Chem. Soc. 2012, 134, 16131) the copper-catalyzed conversion of bromostyrene 19 to 20 in what was termed an activating group recycling strategy. A rhodium complex 23 that incorporates a new chiral cyclopentadienyl ligand was developed (Science 2012, 338, 504) by Nicolai Cramer at the Swiss Federal Institute of Technology in Lausanne and was shown to promote the enantioselective merger of hydroxamic acid derivative 21 and styrene 22 to produce 24.

Paul J. Chirik at Princeton University reported (Science 2012, 335, 567) an iron catalyst that hydrosilylates alkenes with anti-Markovnikov selectivity, as in the conversion of 1 to 2. A regioselective hydrocarbamoylation of terminal alkenes was developed (Chem. Lett. 2012, 41, 298) by Yoshiaki Nakao at Kyoto University and Tamejiro Hiyama at Chuo University, which allowed for the chemoselective conversion of diene 3 to amide 4. Gojko Lalic at the University of Washington reported (J. Am. Chem. Soc. 2012, 134, 6571) the conversion of terminal alkenes to tertiary amines, such as 5 to 6, with anti-Markovnikov selectivity by a sequence of hydroboration and copper-catalyzed amination. Related products such as 8 were prepared (Org. Lett. 2012, 14, 102) by Wenjun Wu at Northwest A&F University and Xumu Zhang at Rutgers via an isomerization-hydroaminomethylation of internal olefin 7. Seunghoon Shin at Hanyang University (experimental work) and Zhi-Xiang Yu at Peking University (computational work) reported (J. Am. Chem. Soc. 2012, 134, 208) that 9 could be directly converted to bicyclic lactone 11 with propiolic acid 10 using gold catalysis. A nickel/Lewis acid multicatalytic system was found (Angew. Chem. Int. Ed. 2012, 51, 5679) by the team of Professors Nakao and Hiyama to effect the addition of pyridones to alkenes, such as in the conversion of 12 to 13. Radical-based functionalization of alkenes using photoredox catalysis was developed (J. Am. Chem. Soc. 2012, 134, 8875) by Corey R.J. Stephenson at Boston University, an example of which was the addition of bromodiethyl malonate across alkene 14 to furnish 15. Samir Z. Zard at Ecole Polytechnique reported (Org. Lett. 2012, 14, 1020) that the reaction of xanthate 17 with terminal alkene 16 led to the product 18. The radical-based addition of nucleophiles including azide to alkenes with Markovnikov selectivity (cf. 19 to 20) was reported (Org. Lett. 2012, 14, 1428) by Dale L. Boger at Scripps La Jolla using an Fe(III)/NaBH4-based system. A remarkably efficient and selective catalyst 22 was found (J. Am. Chem. Soc. 2012, 134, 10357) by Douglas B. Grotjahn at San Diego State University for the single position isomerization of alkenes, which effected the transformation of 21 to 23 in only half an hour.