714-08-9Relevant academic research and scientific papers
Heterobimetallic Pd/Mn and Pd/Co complexes as efficient and stereoselective catalysts for sequential Cu-free Sonogashira coupling–alkyne semi-hydrogenation reactions
Baweja, Saral,Clauss, Reike,Gelman, Dmitri,Hey-Hawkins, Evamarie
supporting information, p. 1344 - 1356 (2022/02/03)
A series of heterobimetallic PdII/MII complexes (MII = Mn, Co) were synthesised and tested as precatalysts for sequential Sonogashira coupling–alkyne semi-hydrogenation reactions to form Z-aryl alkenes. The carbometalated heterobimetallic PdII/CoII complex CoPdL3′ demonstrated an apparent cooperative effect compared to the corresponding monometallic counterparts. This compound was identified as a potent single-molecule catalyst for the one-pot Cu-free Sonogashira coupling of aryl bromides with terminal alkynes followed by chemo- and stereoselective semi-hydrogenation of the alkyne intermediate using NH3·BH3 as a hydrogen source. Furthermore, different aromatic substrates have been tested to show the generality of the reaction for the synthesis of Z-alkenes, including biologically active combretastatin A-4. In addition, the homogeneous nature of the catalytically active species was demonstrated.
Desulfonative Suzuki–Miyaura Coupling of Sulfonyl Fluorides
Bahadori, Maryam,Brykczyńska, Daria,Chatelain, Paul,Moran, Joseph,Muller, Cyprien,Rowley, Christopher N.,Sau, Abhijit
supporting information, p. 25307 - 25312 (2021/10/25)
Sulfonyl fluorides have emerged as powerful “click” electrophiles to access sulfonylated derivatives. Yet, they are relatively inert towards C?C bond forming transformations, notably under transition-metal catalysis. Here, we describe conditions under which aryl sulfonyl fluorides act as electrophiles for the Pd-catalyzed Suzuki–Miyaura cross-coupling. This desulfonative cross-coupling occurs selectively in the absence of base and, unusually, even in the presence of strong acids. Divergent one-step syntheses of two analogues of bioactive compounds showcase the expanded reactivity of sulfonyl fluorides to encompass both S?Nu and C?C bond formation. Mechanistic experiments and DFT calculations suggest oxidative addition occurs at the C?S bond followed by desulfonation to form a Pd-F intermediate that facilitates transmetalation.
Immobilized Pd on a NHC-functionalized metal-organic FrameworkMIL-101(Cr): An efficient heterogeneous catalyst in the heck and copper-free Sonogashira coupling reactions
Niknam, Esmaeil,Panahi, Farhad,Khalafi-Nezhad, Ali
supporting information, (2021/01/12)
A heterogeneous palladium catalyst system based on immobilization of palladium moieties on a N-heterocyclic carbene (NHC) modified metal organic framework (MOF) was developed for the Heck and copper-free Sonogashira coupling reactions. In order to prepare this catalyst system, first, MIL-101(Cr) was functionalized with NHC moieties through a post synthetic modification (PSM) approach, and then Pd metal was stabilized on the prepered MIL-101(Cr)-NHC substrate. This material was characterized using various microscopic and spectroscopic techniques and then was used as an efficient heterogeneous Pd catalyst system in the Heck and copper-free Sonogashira reactions. Results of the heterogeneity tests showed that the Pd-NHC-MIL-101(Cr) catalyst can efficiently catalyzed these coupling reactions heterogeneously and no remarkable changes observed in the morphology and structure of MIL-101(Cr) template during the reaction progress. Also, existence of palladium nanoparticles immobilized on the MOF structure affirmed by the TEM and XPS analysis confirmed the oxidation state of Pd. A variety of alkene and alkyne derivatives were synthesized in good to excellent yields using this heterogeneous Pd catalyst system under normal conditions. More importantly Pd-NHC-MIL-101(Cr) catalyst was simply recovered from the reaction medium without remarkable decreasing in its catalytic activities after five times of reusability. The ICP analysis showed the very low Pd and Cr metals leaching, representing high stability and applicability of this catalyst in Pd coupling reactions.
Copper(0) nanoparticle catalyzed Z-Selective Transfer Semihydrogenation of Internal Alkynes
Moran, Maria Jesus,Martina, Katia,Bieliunas, Vidmantas,Baricco, Francesca,Tagliapietra, Silvia,Berlier, Gloria,De Borggraeve, Wim M.,Cravotto, Giancarlo
, p. 2850 - 2860 (2021/05/06)
The use of copper(0) nanoparticles in the transfer semihydrogenation of alkynes has been investigated as a lead-free alternative to Lindlar catalysts. A stereo-selective methodology for the hydrogenation of internal alkynes to the corresponding (Z)-alkenes in high isolated yields (86% average) has been developed. This green and sustainable transfer hydrogenation protocol relies on non-noble copper nanoparticles for reduction of both electron-rich and electron-deficient, aliphatic-substituted and aromatic- substituted internal alkynes. Polyols, such as ethylene glycol and glycerol, have been proven to act as hydrogen sources, and excellent stereo- and chemoselectivity have been observed. Enabling technologies, such as microwave and ultrasound irradiation are shown to enhance heat and mass transfer, whether used alone or in combination, resulting in a decrease in reaction time from hours to minutes. (Figure presented.).
Wittig Olefination Using Phosphonium Ion-Pair Reagents Incorporating an Endogenous Base
Vetter, Anna C.,Gilheany, Declan G.,Nikitin, Kirill
supporting information, p. 1457 - 1462 (2021/03/08)
Despite common perception, the use of strong bases in Wittig chemistry is utterly unnecessary: we report a series of novel ion-pair phosphonium carboxylate reagents which are essentially "storable ylides". These reagents are straightforwardly prepared in excellent yields, and their fluxional nature permits clean olefination of a broad range of aldehydes and even hemiacetals.
Role of Benzylic Deprotonation in Nickel-Catalyzed Benzylic Dehydrogenation
Zhang, Pengpeng,Cantrell, Rachel L.,Newhouse, Timothy R.
supporting information, p. 1652 - 1656 (2021/07/31)
Alkylarenes are readily functionalized via the corresponding benzylic anions. Benzylic anions have been used for a range of catalytic reactions, including Ni-catalyzed dehydrogenation. Interestingly, the employment of Zn(TMP) 2for slow and incomplete deprotonation of the benzylic position was observed. This manuscript describes a preliminary investigation into the deprotonation of heteroarenes and its relationship to Ni-catalyzed benzylic dehydrogenation.
Structural Effect of Pincer Pd(II)–ONO Complexes Modified with Acylthiourea on Sizes of the In Situ Generated Pd Nanoparticles During Heck Coupling Reaction
Jerome,Babu, S. Ganesh,Karvembu
, p. 1633 - 1645 (2020/10/15)
Abstract: The Pd nanoparticles generated in situ from Pd–pincer complexes catalyzed Heck coupling reaction. For this purpose, new Pd(II)–ONO pincer complexes (1–4) containing acylthiourea ancillary ligand were obtained by treating [Pd(ONO)(CH3CN)] with the respective N-substituted carbamothioyl benzamide ligand (L1–L4). Formation of these complexes was confirmed by UV–Visible, FT-IR, NMR and mass spectroscopic techniques. The sizes of in situ formed Pd nanoparticles were greatly affected by the substituent in ancillary ligand, which in turn influenced their catalytic activity towards Heck coupling reaction. The in situ formed Pd nanoparticles during Heck reaction were removed from the reaction medium and analyzed using HR-TEM to estimate the sizes of the Pd nanoparticles. Complex [Pd(ONO)((N-benzylcarbamothioyl)benzamide)] (1) which does not possess any substituent on the benzyl moiety of acylthiourea produced the smallest Pd nanoparticles with the average particle size of 3.7?nm. Hence, complex 1 showed the utmost catalytic activity. With complex 1, 51–99% of conversion was observed during Heck coupling reaction of styrene with various aryl halides. XPS results confirmed that the recovered black particles were Pd(0). A reasonable recyclability results were achieved by these in situ generated Pd nanoparticles. Graphic Abstract: [Figure not available: see fulltext.]
Aqueous phase semihydrogenation of alkynes over Ni-Fe bimetallic catalysts
Awasthi, Mahendra K.,Barman, Sudipta Roy,Behrens, Silke,Rai, Rohit K.,Singh, Sanjay K.,Singh, Vipin K.
, p. 4968 - 4980 (2020/08/19)
Bimetallic Ni-Fe catalysts (Ni/Fe, 1?:?1, 1?:?3, and 3?:?1) are synthesized and explored for their catalytic activity in semihydrogenation of internal alkynes using H2 gas in water-ethanol solution. Our findings revealed that over the Ni1Fe3 catalyst a high diastereoselectivity for Z-alkenes with a high conversion for a wide range of internal alkynes can be achieved at moderate reaction temperature (40 °C). Notably, the selectivity for the Z-alkenes is enhanced in the presence of n-butyl amine as an additive. Deuterium labeling experiments evidenced that H2 gas becomes dissociated homolytically over the catalyst surface to hydrogenate alkynes to alkenes. Synthesized catalysts were successfully characterized by HR-TEM, SEM, XPS, EDS, P-XRD and H2-TPD.
Iron complex containing diphosphine meta-position carborane ligand as well as preparation method and application of same
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Paragraph 0032; 0036-0037; 0040, (2020/10/14)
The invention relates to an iron complex containing a diphosphine meta-position carborane ligand as well as a preparation method and application of the same. The iron complex is prepared by the following method: reacting n-BuLi with m-carborane m-C2B10H12, then adding halogenated phosphine for continuous reaction, then adding FeCl2 into a reaction system for continuous reaction, after the reactionis finished, separating the reaction product to obtain an iron complex containing a diphosphine m-carborane ligand, and applying the iron complex to catalytic synthesis of a trans-2-alkenyl azaarenecompound. Compared with the prior art, the method shows efficient catalytic activity in synthesis of the trans-2-alkenyl aza-aromatic hydrocarbon compound through direct condensation reaction of 2-methyl aza-aromatic hydrocarbon and aromatic aldehyde, is low in catalyst dosage, mild in reaction condition, high in reaction rate and relatively high in yield, and has a wide application prospect in industry.
[2+2] Photodimerization of Stilbazoles Promoted by Oxalic Acid in Suspension
Nguyen, Thanh Binh,Nguyen, Tuan Minh,Retailleau, Pascal
supporting information, p. 4682 - 4689 (2020/04/15)
In this study, a very simple technique to perform efficiently photodimerization of some vinylpyridines is reported. By irradiating a stirred mixture of several stilbazoles with solid oxalic acid dihydrate dispersed in a nonpolar (i.e., cyclohexane) or moderately polar (benzene, dichloromethane, dioxane) solvent, the corresponding dimeric cyclobutane adducts were obtained in high yields and excellent regio- and stereoselectivities. The strategy could also be applied successfully to oily, waxy, or even insoluble stilbazoles. Moreover, the oxalic acid loading could be lowered to substoichiometric amounts. When further optimizations were needed, our strategy was found to be highly flexible to identify other oligocarboxylic acids as alternative additives to improve, or even overturn, the regioselectivity. Oxalic acid and other oligocarboxylic acids were found to be capable of orienting more than 50 stilbazoles toward photodimerization under these conditions.
