34702-96-0Relevant articles and documents
Enzyme stabilization via computationally guided protein stapling
Moore, Eric J.,Zorine, Dmitri,Hansen, William A.,Khare, Sagar D.,Fasan, Rudi
, p. 12472 - 12477 (2017)
Thermostabilization represents a critical and often obligatory step toward enhancing the robustness of enzymes for organic synthesis and other applications. While directed evolution methods have provided valuable tools for this purpose, these protocols are laborious and time-consuming and typically require the accumulation of several mutations, potentially at the expense of catalytic function. Here, we report a minimally invasive strategy for enzyme stabilization that relies on the installation of genetically encoded, nonreducible covalent staples in a target protein scaffold using computational design. This methodology enables the rapid development of myoglobin-based cyclopropanation biocatalysts featuring dramatically enhanced thermostability (ΔTm = +18.0°C and ΔT50 = +16.0°C) as well as increased stability against chemical denaturation [ΔCm (GndHCl) = 0.53 M], without altering their catalytic efficiency and stereoselectivity properties. In addition, the stabilized variants offer superior performance and selectivity compared with the parent enzyme in the presence of a high concentration of organic cosolvents, enabling the more efficient cyclopropanation of a water-insoluble substrate. This work introduces and validates an approach for protein stabilization which should be applicable to a variety of other proteins and enzymes.
Photoswitching of stereoselectivity in catalysis using a copper dithienylethene complex
Sud, David,Norsten, Tyler B.,Branda, Neil R.
, p. 2019 - 2021 (2005)
(Chemical Equation Presented) Light controls the outcome of a stereoselective reaction. Only in the ring-open form can the shown chelate copper(I) complex transfer its chirality to the cyclopropanation of styrene with ethyl diazoacetate. Irradiation with UV light triggers the ring-closing reaction of the ligand rendering it ineffective (see scheme).
Electrostatic immobilization of bis(oxazoline)-copper complexes on mesoporous crystalline materials: Cation exchange vs. incipient wetness methods
Feldman, Robert A.,Fraile, José M.
, p. 67 - 73 (2014)
Chiral copper complexes with bis(oxazoline) and azabis(oxazoline) ligands have been immobilized by non-covalent interactions on mesoporous materials. The presence of negative charges achieved by the isomorphous substitution of silicon by aluminium is required to retain the complexes on the support. Cation-exchange was found to be not as efficient as observed with layered clays, and produce catalysts which lose their chiral ligand and give low enantioselectivity. A method employing incipient wetness produces more stable catalysts, whose activity varies to some extent according to the structure of the mesoporous material on which it is supported, and the nature of the chiral ligand.
High-valent tin(IV) porphyrins: Efficient and selective catalysts for cyclopropanation of styrene derivatives with EDA under mild conditions
Gharaati, Shadab,Moghadamb, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj,Barati, Behjat,Sadegh, Faranaz
, p. 78 - 82 (2013)
An efficient and selective method for cyclopropanation of styrene derivatives with ethyl diazoacetate (EDA) catalyzed by tin(IV) tetraphenylporphyrinato trifluoromethanesulfonate, [SnIV(TPP)(OTf)2], and tin(IV)tetraphenylporphyrinato tetrafluoroborate, [SnIV(TPP)(BF 4)2] is reported. These electron-deficient catalysts catalyzed the cyclopropanation of styrene derivatives in high yields and short reaction times under mild conditions. The reactions were highly selective and only trans-isomers were produced. Electron-rich styrenes were reacted faster than electron-poor ones. The catalysts were reused several times without loss of their catalytic activity and diastereoselectivity.
A non-fluorous copper catalyst for the styrene cyclopropanation reaction in a fluorous medium
Urbano, Juan,Izarra, Rocio,Gomez-Ariza, Jose Luis,Trofimenko, Swiatoslaw,Diaz-Requejo, M. Mar,Perez, Pedro J.
, p. 1000 - 1002 (2006)
The complex TpBr3Cu(NCMe) (1), containing no fluorine atoms, can be dissolved in the perfluoropolyether FOMBLIN and employed as a catalyst for the styrene cyclopropanation reaction with ethyl diazoacetate, with activities and diastereoselectivities identical to those observed under homogeneous conditions with the advantage of being able to use a fluorous separation technique for catalyst recycling. The Royal Society of Chemistry 2006.
Asymmetric cyclopropanation of styrene with ethyl diazoacetate using a N2P2-ligand ruthenium(II) catalyst: Axial ligand controlled enantioselectivity
Zheng, Zhuo,Yao, Xiaoquan,Li, Chen,Chen, Huilin,Hu, Xinquan
, p. 2847 - 2849 (2001)
The N2P2-Ru(II) complex 1, activated by silver triflate, exhibited good catalytic activity but low enantioselectivity in the asymmetric cyclopropanation of styrene with ethyl diazoacetate. N-Donor additives were introduced into the a
New Axially Chiral Bis(dihydrooxazoles) as Ligands in Stereoselecrive Transition-Metal Catalysis
Rippert, Andreas Johannes
, p. 676 - 687 (1998)
The new, axially chiral bis(4,5-dihydrooxazoles) 4 have been synthesized in a straightforward manner, starting from the substituted, racemic 1,1′-biphenyl-2,2′-dicarboxylic acids 1 and optically active amino alcohols 2. The adducts were resolved by medium-performance liquid chromatography (MPLC; see Scheme 1). Formation of CuI complexes of 4 was followed by 1H-NMR spectroscopy. The catalytic behavior of these complexes has been investigated by asymmetric cyclopropanation of styrene with ethyl diazoacetate. Beside the influence of steric factors, a significant electronic effect on asymmetric induction could also be observed (see Scheme 2 and Table).
Improved methodology for non-covalent immobilization of tert-butyl-azabis(oxazoline)-copper complex on Al-MCM41
Feldman, Robert A.,Fraile, José M.
, p. 166 - 173 (2015)
Abstract Copper sites are supported on Al-MCM41 by thermally treating copper(II) triflate that was deposited using the incipient wetness method. The change of the chemical state of the triflate anions following thermal treatment is monitored using TGA and SEM-EDX. Thermal treatment yields copper sites that then can be modified with chiral tert-butyl-azabis(oxazoline) by adding a solution of this ligand to the support using incipient wetness. The catalyst produced in this way is efficient and stable with good enantioselectivity, and can be used in the cyclopropanation of styrene with ethyl diazoacetate under conditions employing an elevated temperature. The use of thermal treatment in the catalyst preparation method produces catalysts that are superior to the solids prepared by cation exchange or incipient wetness of the pre-formed complex.
A conformational toolbox of oxazoline ligands
Davies, Ian W.,Gerena, Linda,Cai, Dongwei,Larsen, Robert D.,Verhoeven, Thomas R.,Reider, Paul J.
, p. 1145 - 1148 (1997)
A toolbox of bis(oxazoline) and pyridinebis(oxazoline) ligands 6, 7, 8 has been used to probe conformational effects in Cu(II)-catalyzed Diels-Alder and Ru(II)-catalyzed cyclopropanation reactions.
Chiral imidazoles and imidazole N-oxides as ligands for stereoselective cyclopropanation reactions
Mloston, Grzegorz,Mucha, Paulina,Heimgartner, Heinz
, p. 89 - 91 (2012)
New, optically active ligands derived from imidazole were tested in the cyclopropanation reaction of styrene using ethyl diazoacetate and copper(I) triflate as a catalyst.
Optimization of enantiocontrol in cis-selective cyclopropanation reactions catalyzed by dirhodium(II) tetrakis[alkyl 2-oxaazetidine-4(S)- carboxylates]
Doyle, Michael P.,Davies, Simon B.,Hu, Wenhao
, p. 867 - 868 (2000)
Both intermolecular and macrocyclic intramolecular cyclopropanation reactions occur with greater selectivity for the cis-(Z)-diastereoisomer than for the trans-(E)-diastereomer in reactions catalyzed by chiral dirhodium(II) azetidinone-carboxylates; the i
Multipurpose box- and azabox-based immobilized chiral catalysts
Fraile, Jose M.,Perez, Ignacio,Mayoral, Jose A.,Reiser, Oliver
, p. 1680 - 1688 (2006)
Azabis(oxazolines) can be used as chiral ligands in the copper-catalyzed enantioselective Mukaiyama aldol reaction. When supported on solids, azabis(oxazoline)-copper complexes are more easily deactivated than their analogous bis(oxazoline)-copper complex
Reversible Metalation and Catalysis with a Scorpionate-like Metallo-ligand in a Metal-Organic Framework
Sun, Chenyue,Skorupskii, Grigorii,Dou, Jin-Hu,Wright, Ashley M.,Dinca, Mircea
, p. 17394 - 17398 (2018)
The installation of metallo-ligands in metal-organic frameworks (MOFs) is an effective means to create site-isolated metal centers toward single-site heterogeneous catalysis. Although trispyrazolyborate (Tp) and tripyrazolylmethane (Tpm) form one of the most iconic classes of homogeneous catalysts, neither has been used as a metallo-ligand for the generation of MOFs thus far. Here, we show that upon in situ metalation with CuI, a tricarboxylated Tpm ligand reacts with ZrOCl2 to generate a new MOF exhibiting neutral scorpionate-like chelating sites. These sites undergo for facile demetalation and remetalation with retention of crystallinity and porosity. When remetalated with CuI, the MOF exhibits spectroscopic features and catalytic activity for olefin cyclopropanation reactions that are similar to the molecular [Cu(CH3CN)Tpm]PF6 complex (Tpm? = tris(3,5-dimethylpyrazolyl)methane). These results demonstrate the inclusion of Tp or Tpm metallo-ligands in a MOF for the first time and provide a blueprint for immobilizing Tpm? catalysts in a spatially isolated and well-defined environment.
Unprecedented stereoselective synthesis of catalytically active chiral Mo3CuS4 clusters
Feliz, Marta,Guillamon, Eva,Llusar, Rosa,Vicent, Cristian,Stiriba, Salah-Eddine,Perez-Prieto, Julia,Barberis, Mario
, p. 1486 - 1492 (2006)
Cluster excision of polymeric {Mo3S7Cl 4}n phases with chiral phosphane (+)-1,2-bis[(2R,5R)-2,5- (dimethylphospholan-1-yl)]ethane ((R,R)-Me-BPE) or with its enantiomer ((S,S)-Me-BPE) yields the stereoselective formation of the trinuclear cluster complexes [Mo3S4{(R,R)-Me-BPE}3Cl 3]+ ([(P)-1]+) and [Mo3S 4{(S,S)-Me-BPE}3Cl3] + ([(M)-l] +), respectively. These complexes posses an incomplete cuboidal structure with the metal atoms defining an equilateral triangle and one capping and three bridging sulfur atoms. The P and M symbols refer to the rotation of the chlorine atoms around the C3 axis, with the capping sulphur atom pointing towards the viewer. Incorporation of copper into these trinuclear complexes affords heterodimetallic cubane-type compounds of formula [Mo 3CuS4-{(R,R)-Me-BPE}3Cl4] + ([(P)-2]+) or [Mo3CuS4{(S,S)-Me- BPE}3Cl4]+ ([(M)-2]+), respectively, for which the chirality of the trinuclear precursor is preserved in the final product. Cationic complexes [(P)-1]+, [(M)-1]+, [(P)-2]+, and [(M)-2]+ combine the chirality of the metal cluster framework with that of the optically active diphosphane ligands. The known racemic [Mo3CuS4-(dmpe)3Cl 4]+ cluster (dmpe = 1,2-bis-(dimethylphosphanyl)ethane) as well as the new enantiomerically pure Mo3CuS4 [(P)-2]+ and [(M)-2]+ complexes are efficient catalysts for the intramolecular cyclopropanation of 1-diazo-5-hexen-2-one (3) and for the intermolecular cyclopropanation of alkenes, such as styrene and 2-phenylpropene, with ethyl diazoacetate. In all cases, the cyclopropanation products were obtained in high yields. The diastereoselectivity in the intermolecular cyclopropanation of the alkenes and the enantioselectivity in the inter- or intramolecular processes are only moderate.
High trans selectivity in the copper bis(oxazoline)-catalyzed asymmetric cyclopropanation of olefins by (trimethylsilyl)diazomethane
France, Marcia B.,Milojevich, Allyn K.,Stitt, Tracy A.,Kim, Angela J.
, p. 9287 - 9290 (2003)
Copper(I) bis(oxazoline) species are among the most enantioselective cyclopropanation catalysts that have been reported, although these catalysts generally give low diastereoselectivities. We have observed greatly improved diastereoselectivities using (tr
Preparation of a resin-bound arene - Ruthenium complex and assessment of its use in enol formate synthesis and olefin cyclopropanation
Leadbeater, Nicholas E.,Scott, Kathryn A.,Scott, Lucy J.
, p. 3231 - 3232 (2000)
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Highly enantioselective synthesis of cyclopropylphosphonates catalyzed by chiral ruthenium porphyrins
Ferrand, Yann,Le Maux, Paul,Simonneaux, Gerard
, p. 3211 - 3214 (2004)
(Chemical Equation Presented) The asymmetric addition of diisopropyl diazomethylphosphonate to styrene derivatives was carried out by using chiral ruthenium porphyrins as catalysts. The reaction proceeded under mild conditions and gave trans-cyclopropylph
Asymmetric heterogeneous carbene transfer catalyzed by optically active ruthenium spirobifluorenylporphyrin polymers
Ferrand, Yann,Poriel, Cyril,Le Maux, Paul,Rault-Berthelot, Joelle,Simonneaux, Gerard
, p. 1463 - 1472 (2005)
Anodic oxidation of chiral ruthenium complexes of spirobifluorenylporphyrins leads to the coating of the working electrode by insoluble optically active films whose electrochemical behaviour and physicochemical properties are described. After removal from
Clay-supported bis(oxazoline)-copper complexes as heterogeneous catalysts of enantioselective cyclopropanation reactions
Fraile, Jose M.,Garcia, Jose I.,Mayoral, Jose A.,Tarnai, Tibor
, p. 3997 - 4008 (1998)
Several chiral bis(oxazoline)-copper complexes are supported by cation exchange in laponite, bentonite and K10 montmorillonite, and their catalytic performances are compared in the benchmark cyclopropanation reaction of styrene with ethyl diazoacetate. Th
Synthesis of new chiral terpyridine mono-N-oxide and di-N-oxide ligands and their applications in copper-catalyzed asymmetric cyclopropanation
Wong, Wing-Leung,Lee, Wing-Sze,Kwong, Hoi-Lun
, p. 1485 - 1492 (2002)
New families of chiral terpyridine mono-N-oxides L1-L3 and di-N-oxides L4-L6, were synthesized in moderate to good yields by simple oxidation of their corresponding terpyridines with m-CPBA. The copper(II) trifl
Six new 3d-4f heterometallic coordination polymers constructed from pyrazole-bridged CuIILnIII dinuclear units
Yang, Ting-Hai,Silva, Ana Rosa,Shi, Fa-Nian
, p. 13997 - 14005 (2013)
Reactions of lanthanide chlorides, copper hydroxycarbonate and 3,5-pyrazole dicarboxylic acid (H3pdc) under hydrothermal conditions result in six new 3d-4f heterometallic coordination polymers with two types of structures. Compounds [CuLn2(pdc)2(Hpdc)(H2O) 4]·2H2O (Ln = Tb (1), Dy (2), Er (3), and Y (4) exhibit a layered porous structure, made up of CuIILnIII di-nuclear units which are connected by protonated Hpdc2- ligand, while the others [Cu3Ln4(pdc)6(H 2O)8] (Ln = Eu (5), Gd (6)) display a three-dimensional (3-D) framework structure, in which six CuIILnIII di-nuclear units are cross-linked by two coordinated lanthanide atoms. The catalytic properties of 3 are investigated showing its activity and recyclability in the reaction of cyclopropanation of styrene.
Carbohydrate-derived bis(oxazoline) ligand in the total synthesis of grenadamide
Minuth, Tobias,Boysen, Mike M.K.
, p. 2799 - 2803 (2010)
Using an optimised carbohydrate-based bis(oxazoline) ligand and copper(I) triflate, unactivated aliphatic alkenes were cyclopropanated with simple ethyl diazoacetate, giving the corresponding products in good yields and high stereoselectivities. The trans-disubstituted cyclopropyl carboxylic acid ester derived from 1-nonene was subsequently used as the key intermediate for the synthesis of the (+)-enantiomer of the natural product (-)-grenadamide. The efficient and high-yielding approach towards grenadamide reported here is the first to utilise asymmetric cyclopropanation for the construction of the chiral cyclopropyl unit. Georg Thieme Verlag Stuttgart.
Reversible microencapsulation of pybox-Ru chiral catalysts: Scope and limitations
Cornejo, Alfonso,Fraile, José M.,García, José I.,Gil, María J.,Martínez-Merino, Víctor,Mayoral, José A.
, p. 12107 - 12110 (2005)
Chiral Pybox-Ru catalysts can be microencapsulated into linear polystyrene as a method to recover and recycle the valuable catalyst. These catalysts allow 60-68% yields to be achieved with enantioselectivities in the range 75-85% ee in the benchmark cyclo
Immobilisation of bis(oxazoline)-copper complexes on clays and nanocomposites. Influence of different parameters on activity and selectivity
Fraile, Jose M.,Garcia, Jose I.,Harmer, Mark A.,Herrerias, Clara I.,Mayoral, Jose A.,Reiser, Oliver,Werner, Heiko
, p. 3290 - 3295 (2002)
Bis(oxazoline)-copper complexes, immobilised by electrostatic interactions on Laponite and Nafion/silica nanocomposites, have been tested as catalysts in the cyclopropanation of styrene with ethyl diazoacetate. Several factors play a decisive role in the
Asymmetric catalysis. LXXX. An optically-active tetrakispyrazolylborate: Synthesis and use in Cu-catalyzed enantioselective cyclopropanation
Brunner, Henri,Singh, Udai P.,Boeck, Thomas,Altmann, Stefan,Scheck, Thomas,Wrackmeyer, Bernd
, p. C16 - C18 (1993)
The synthesis of the optically-active sodium salt of tetrakis(4,5,6,7-tetrahydro-7,8,8-trimethyl-2H-4,7-methanoindazolyl)borate, (1) is reported.Cu-based in situ catalysts containing give an enantiomeric excess of up to 62percent in the enantioselective cyclopropanation of styrene with ethyl diazoacetate.
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.
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.
