97-71-2Relevant academic research and scientific papers
Electrochemical Ring-Opening Dicarboxylation of Strained Carbon-Carbon Single Bonds with CO2: Facile Synthesis of Diacids and Derivatization into Polyesters
Liao, Li-Li,Wang, Zhe-Hao,Cao, Ke-Gong,Sun, Guo-Quan,Zhang, Wei,Ran, Chuan-Kun,Li, Yiwen,Chen, Li,Cao, Guang-Mei,Yu, Da-Gang
supporting information, p. 2062 - 2068 (2022/02/10)
Diacids are important monomers in the polymer industry to construct valuable materials. Dicarboxylation of unsaturated bonds, such as alkenes and alkynes, with CO2 has been demonstrated as a promising synthetic method. However, dicarboxylation of C-C single bonds with CO2 has rarely been investigated. Herein we report a novel electrochemical ring-opening dicarboxylation of C-C single bonds in strained rings with CO2. Structurally diverse glutaric acid and adipic acid derivatives were synthesized from substituted cyclopropanes and cyclobutanes in moderate to high yields. In contrast to oxidative ring openings, this is also the first realization of an electroreductive ring-opening reaction of strained rings, including commercialized ones. Control experiments suggested that radical anions and carbanions might be the key intermediates in this reaction. Moreover, this process features high step and atom economy, mild reaction conditions (1 atm, room temperature), good chemoselectivity and functional group tolerance, low electrolyte concentration, and easy derivatization of the products. Furthermore, we conducted polymerization of the corresponding diesters with diols to obtain a potential UV-shielding material with a self-healing function and a fluorine-containing polyester, whose performance tests showed promising applications.
Controlling the Activity of a Caged Cobalt-Porphyrin-Catalyst in Cyclopropanation Reactions with Peripheral Cage Substituents
Mouarrawis, Valentinos,Bobylev, Eduard O.,de Bruin, Bas,Reek, Joost N. H.
supporting information, p. 2890 - 2898 (2021/07/09)
In this study, three novel cubic cages were synthesized and utilized to encapsulate a catalytically active cobalt(II) meso-tetra(4-pyridyl)porphyrin guest. The newly developed caged catalysts (Co-G@Fe8(Zn-L ? 1)6, Co-G@Fe8(Zn-L ? 2)6 and Co-G@Fe8(Zn-L ? 3)6) can be easily synthesized and differ in exo-functionalization, which are either none, polar or apolar groups. This leads to a different polarity of the peripheral environment surrounding the cage, which affects the (relative) local concentration of the substrates surrounding the cage and hence indirectly influences the substrate availability of the catalysis embedded in the active site of the caged catalyst systems. The resulting increased local substrate concentrations give rise to higher catalytic activities of the respective caged catalyst in metalloradical catalyzed cyclopropanation reactions. Interestingly, the catalytic activity is the highest when the apolar cage catalyst (Co-G@Fe8(Zn-L ? 1)6) is used, and lowest with the polar analog (Co-G@Fe8(Zn-L ? 3)6). In addition, the catalytic activity of the cage without exo-functionalities (Co-G@Fe8(Zn-L ? 2)6) is nearly two times lower than that of Co-G@Fe8(Zn-L ? 1)6 and three times higher than that of Co-G@Fe8(Zn-L ? 3)6, which further demonstrates the effect of the peripheral functionalities on the cyclopropanation reaction.
Synthesis of ruthenium–dithiocarbamate chelates bearing diphosphine ligands and their use as latent initiators for atom transfer radical additions
Aldin, Mohammed Zain,Delaude, Lionel,Zaragoza, Guillermo
supporting information, (2021/08/03)
Nine representative [Ru(S2CNEt2)2(diphos)] complexes were prepared in almost quantitative yields (91–97%) from [RuCl2(p-cymene)]2, sodium diethyldithiocarbamate trihydrate, and a diphosphine (dppm, dppe, dppp, dppb, dpppe, dppen, dppbz, dppf, or DPEphos), using a novel, straightforward, one-pot procedure. The recourse to a monomodal microwave reactor was instrumental in reaching the thermodynamic equilibria favoring the targeted monometallic trichelates. All the products were fully characterized by using various analytical techniques and the molecular structures of seven of them were determined by X-ray crystallography. NMR, XRD, and IR spectroscopies evidenced a significant contribution of the thioureide resonance form Et2N+=CS22– to the electronic structure of the 1,1-dithiolate ligand. MS/MS spectrometry showed the formation of phosphine-free [Ru(S2CNEt2)2]+ cations in the gas phase, except when starting from [Ru(S2CNEt2)2(dppbz)]. The activity of the nine complexes was probed in three different catalytic processes, viz., the cyclopropanation of styrene with ethyl diazoacetate, the synthesis of vinyl esters from benzoic acid and 1-hexyne, and the atom transfer radical addition (ATRA) of carbon tetrachloride and methyl methacrylate. In the first two reactions, the saturated trichelates were poorly efficient. This was most likely due to their high stability, which prevented the formation of coordinatively unsaturated species. Contrastingly, with a turnover number of 2000 and an initial turnover frequency of 2080 h–1 for a 0.05 mol% catalyst loading, the [Ru(S2CNEt2)2(dppm)] complex emerged as a very robust, latent ATRA initiator, whose activity matched or outperformed those displayed by the most efficient ruthenium catalysts described so far.
Catalytic cyclopropanation, antimicrobial, and DFT properties of some chelated transition metal(II) complexes
Ababneh, Taher S.,Al-Dawood, Lina A.,Al-Momani, Waleed M.,Hijazi, Ahmed K.,Taha, Ziyad A.
, (2020/12/25)
Transition Metal (II) complexes of general formula [MII(NH2C2H4NH2)3][B(C6F5)4]2 (1-6), where (M= Mn, Fe, Co, Ni, Cu, Zn) have been synthesized and characterized in the solid state and in solution using elemental, thermogravimetric analysis, EPR, 11B-NMR and IR spectroscopy. All complexes were used as catalysts for the cyclopropanation reaction with a variety of olefins. Excellent yields up to 93% were obtained using complex 5. All prepared complexes were used as anti-bacterial agents against different types of bacteria (Gram-negative and Gram-positive), and as anti-fungal agents. Complex 6 showed the highest activity with MIC value of 8 μg/mL against Staphylococcus aureus (Gram-positive bacteria), and of 16 μg/mL against candida albicans. To get more insights into their structural features, molecular geometries of all prepared complexes were fully optimized using density functional theory calculations at the M06-2X/6-311+G** level of theory.
Noncanonical Heme Ligands Steer Carbene Transfer Reactivity in an Artificial Metalloenzyme**
Dunkelmann, Daniel,Hayashi, Takahiro,Hilvert, Donald,Mittl, Peer R. E.,Ota, Yusuke,Pott, Moritz,Tinzl, Matthias
supporting information, p. 15063 - 15068 (2021/06/09)
Changing the primary metal coordination sphere is a powerful strategy for tuning metalloprotein properties. Here we used amber stop codon suppression with engineered pyrrolysyl-tRNA synthetases, including two newly evolved enzymes, to replace the proximal histidine in myoglobin with Nδ-methylhistidine, 5-thiazoylalanine, 4-thiazoylalanine and 3-(3-thienyl)alanine. In addition to tuning the heme redox potential over a >200 mV range, these noncanonical ligands modulate the protein's carbene transfer activity with ethyl diazoacetate. Variants with increased reduction potential proved superior for cyclopropanation and N–H insertion, whereas variants with reduced Eo values gave higher S–H insertion activity. Given the functional importance of histidine in many enzymes, these genetically encoded analogues could be valuable tools for probing mechanism and enabling new chemistries.
Controllable stereoinversion in DNA-catalyzed olefin cyclopropanationviacofactor modification
Cheng, Yu,Hao, Jingya,Jia, Guoqing,Li, Can,Lu, Shengmei,Miao, Wenhui
, p. 7918 - 7923 (2021/06/16)
The assembly of DNA with metal-complex cofactors can form promising biocatalysts for asymmetric reactions, although catalytic performance is typically limited by low enantioselectivities and stereo-control remains a challenge. Here, we engineer G-quadruplex-based DNA biocatalysts for an asymmetric cyclopropanation reaction, achieving enantiomeric excess (eetrans) values of up to +91% with controllable stereoinversion, where the enantioselectivity switches to ?72% eetransthrough modification of the Fe-porphyrin cofactor. Complementary circular dichroism, nuclear magnetic resonance, and fluorescence titration experiments show that the porphyrin ligand of the cofactor participates in the regulation of the catalytic enantioselectivityviaa synergetic effect with DNA residues at the active site. These findings underline the important role of cofactor modification in DNA catalysis and thus pave the way for the rational engineering of DNA-based biocatalysts.
Synthesis, structure and reactivity of iridium complexes containing a bis-cyclometalated tridentate C^N^C ligand
Cheng, Shun-Cheung,Cheung, Wai-Man,Chong, Man-Chun,Ko, Chi-Chiu,Leung, Wa-Hung,Sung, Herman H.-Y.,Williams, Ian D.
, p. 8512 - 8523 (2021/06/28)
In an effort to synthesize cyclometalated iridium complexes containing a tridentate C^N^C ligand, transmetallation of [Hg(HC^N^C)Cl] (1) (H2C^N^C = 2,6-bis(4-tert-butylphenyl)pyridine) with various organoiridium starting materials has been studied. The treatment of1with [Ir(cod)Cl]2(cod = 1,5-cyclooctadiene) in acetonitrile at room temperature afforded a hexanuclear Ir4Hg2complex, [Cl(κ2C,N-HC^N^C)(cod)IrHgIr(cod)Cl2]2(2), which features Ir-Hg-Ir and Ir-Cl-Ir bridges. Refluxing2with sodium acetate in tetrahydrofuran (thf) resulted in cyclometalation of the bidentate HC^N^C ligand and formation of trinuclear [(C^N^C)(cod)IrHgIr(cod)Cl2] (3). On the other hand, refluxing [Ir(cod)Cl]2with1and sodium acetate in thf yielded [Ir(C^N^C)(cod)(HgCl)] (4). Chlorination of4with PhICl2gave [Ir(C^N^C)(cod)Cl]·HgCl2(5·HgCl2) that reacted with tricyclohexylphosphine to yield Hg-free [Ir(C^N^C)(cod)Cl] (5). Chloride abstraction of5with silver(i) triflate (AgOTf) gave [Ir(C^N^C)(cod)(H2O)](OTf) (6) that can catalyze the cyclopropanation of styrene with ethyl diazoacetate. Reaction of1and [Ir(CO)2Cl(py)] (py = pyridine) with sodium acetate in refluxing thf afforded [Ir(C^N^C)(HgCl)(py)(CO)] (7), in which the carbonyl ligand is coplanar with the C^N^C ligand. On the other hand, refluxing1with (PPh4)[Ir(CO)2Cl2] and sodium acetate in acetonitrile gave [Ir(C^N^C)(κ2C,N-HC^N^C)(CO)] (8), the carbonyl ligand of which istransto the pyridyl ring of the bidentate HC^N^C ligand. Upon irradiation with UV light8in thf was isomerized to8′, in which the carbonyl istransto a phenyl group of the bidentate HC^N^C ligand. The isomer pair8and8′exhibited emission at 548 and 514 nm in EtOH/MeOH at 77 K with lifetime of 84.0 and 64.6 μs, respectively. Protonation of8withp-toluenesulfonic acid (TsOH) afforded the bis(bidentate) tosylate complex [Ir(κ2C,N-HC^N^C)2(CO)(OTs)] (9) that could be reconverted to8upon treatment with sodium acetate. The electrochemistry of the Ir(C^N^C) complexes has been studied using cyclic voltammetry. Reaction of [Ir(PPh3)3Cl] with1and sodium acetate in refluxing thf led to isolation of the previously reported compound [Ir(κ2P,C-C6H4PPh2)2(PPh3)Cl] (10). The crystal structures of2-5,8,8′,9and10have been determined.
Encapsulating ruthenium in silica using a single source precursor: Differing outcomes for a cycloaddition reaction
Barik, Chandan Kr,Ganguly, Rakesh,Garcia, Felipe,Leong, Weng Kee
, (2020/07/10)
The complex [Ru2(CO)4(μ-O2CCH2OSi(OEt)3)2(PPh3)2] was used as a single-source precursor to prepare silica-encapsulated ruthenium via hydrolysis followed by calcination. While the silica-encapsulated ruthenium catalyst and the molecular precursor both catalysed the [2 + 1] cycloaddition reaction between alkenes and ethyl diazoacetate to form cyclopropanes, the intermediate hydrolysis product partially directed the reaction towards [2 + 3] cycloaddition to form cyclic five-membered pyrazolines.
Enhancedcis- And enantioselective cyclopropanation of styrene catalysed by cytochrome P450BM3 using decoy molecules
Suzuki, Kazuto,Shisaka, Yuma,Stanfield, Joshua Kyle,Watanabe, Yoshihito,Shoji, Osami
, p. 11026 - 11029 (2020/10/05)
We report the enhancedcis- and enantioselective cyclopropanation of styrene catalysed by cytochrome P450BM3 in the presence of dummy substrates,i.e.decoy molecules. With the aid of the decoy molecule R-Ibu-Phe, diastereoselectivity for thecisdiastereomers
A de novo peroxidase is also a promiscuous yet stereoselective carbene transferase
Stenner, Richard,Steventon, Jack W.,Seddon, Annela,Anderson, J.L. Ross
, p. 1419 - 1428 (2020/01/28)
By constructing an in vivo-assembled, catalytically proficient peroxidase, C45, we have recently demonstrated the catalytic potential of simple, de novo-designed heme proteins. Here, we show that C45's enzymatic activity extends to the efficient and stereoselective intermolecular transfer of carbenes to olefins, heterocycles, aldehydes, and amines. Not only is this a report of carbene transferase activity in a completely de novo protein, but also of enzyme-catalyzed ring expansion of aromatic heterocycles via carbene transfer by any enzyme.
