- Ruthenium(II)Cl2-Bis(oxazolinyl)bipyridine Complex. Its Structure and Reactivity
-
A mixture of 2 and 6,6'-bis(oxazolinyl)-2,2'-bipyridine (Bipymox-ip) was heated in ethanol at 70 deg C to produce Ru(II)Cl2(Bipymox-ip), of which structure was clarified by X-ray analysis to show that Bipymox-ip binds as a tetradentate ligand.Its catalytic activities for transformations of diazoacetates in dimerization and cyclopropanation with styrene were examined and its spectroelectrochemistry was studied.
- Nishiyama, Hisao,Park, Soon-Bong,Haga, Masa-aki,Aoki, Katsuyuki,Itoh, Kenji
-
-
Read Online
- Controllable stereoinversion in DNA-catalyzed olefin cyclopropanationviacofactor modification
-
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.
- Cheng, Yu,Hao, Jingya,Jia, Guoqing,Li, Can,Lu, Shengmei,Miao, Wenhui
-
p. 7918 - 7923
(2021/06/16)
-
- Selective carbene transfer to amines and olefins catalyzed by ruthenium phthalocyanine complexes with donor substituents
-
Electron-rich ruthenium phthalocyanine complexes were evaluated in carbene transfer reactions from ethyl diazoacetate (EDA) to aromatic and aliphatic olefins as well as to a wide range of aromatic, heterocyclic and aliphatic amines for the first time. It was revealed that the ruthenium octabutoxyphthalocyanine carbonyl complex [(BuO)8Pc]Ru(CO) is the most efficient catalyst converting electron-rich and electron-poor aromatic olefins to cyclopropane derivatives with high yields (typically 80-100%) and high TON (up to 1000) under low catalyst loading and nearly equimolar substrate/EDA ratio. This catalyst shows a rare efficiency in the carbene insertion into amine N-H bonds. Using a 0.05 mol% catalyst loading, a high amine concentration (1 M) and 1.1 eq. of EDA, a number of structurally divergent amines were selectively converted to mono-substituted glycine derivatives with up to quantitative yields and turnover numbers reaching 2000. High selectivity, large substrate scope, low catalyst loading and practical reaction conditions place [(BuO)8Pc]Ru(CO) among the most efficient catalysts for the carbene insertion into amines.
- Cailler, Lucie P.,Kroitor, Andrey P.,Martynov, Alexander G.,Gorbunova, Yulia G.,Sorokin, Alexander B.
-
supporting information
p. 2023 - 2031
(2021/02/26)
-
- A de novo peroxidase is also a promiscuous yet stereoselective carbene transferase
-
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.
- Stenner, Richard,Steventon, Jack W.,Seddon, Annela,Anderson, J.L. Ross
-
p. 1419 - 1428
(2020/01/28)
-
- Comparative Study of the Electronic Structures of μ-Oxo, μ-Nitrido, and μ-Carbido Diiron Octapropylporphyrazine Complexes and Their Catalytic Activity in Cyclopropanation of Olefins
-
The electronic structure of three single-Atom bridged diiron octapropylporphyrazine complexes (FePzPr8)2X having Fe(III)-O-Fe(III), Fe(III)-N-Fe(IV) and Fe(IV)-C-Fe(IV) structural units was investigated by M?ssbauer spectroscopy and density functional theory (DFT) calculations. In this series, the isomer shift values decrease, whereas the values of quadrupole splitting become progressively greater indicating the increase of covalency of Fe-X bond in the μ-oxo, μ-nitrido, μ-carbido row. The M?ssbauer data point to low-spin systems for the three complexes, and calculated data with B3LYP-D3 show a singlet state for μ-oxo and μ-carbido and a doublet state for μ-nitrido complexes. An excellent agreement was obtained between B3LYP-D3 optimized geometries and X-ray structural data. Among (FePzPr8)2X complexes, μ-oxo diiron species showed a higher reactivity in the cyclopropanation of styrene by ethyl diazoacetate to afford a 95% product yield with 0.1 mol % catalyst loading. A detailed DFT study allowed to get insight into electronic structure of binuclear carbene species and to confirm their involvement into carbene transfer reactions.
- Cailler, Lucie P.,Clémancey, Martin,Barilone, Jessica,Maldivi, Pascale,Latour, Jean-Marc,Sorokin, Alexander B.
-
p. 1104 - 1116
(2020/02/04)
-
- Origin of High Stereocontrol in Olefin Cyclopropanation Catalyzed by an Engineered Carbene Transferase
-
Recent advances in metalloprotein engineering have led to the development of a myoglobin-based catalyst, Mb(H64V,V68A), capable of promoting the cyclopropanation of vinylarenes with high efficiency and high diastereo- and enantioselectivity. Whereas many enzymes evolved in nature often exhibit catalytic proficiency and exquisite stereoselectivity, how these features are achieved for a non-natural reaction has remained unclear. In this work, the structural determinants responsible for chiral induction and high stereocontrol in Mb(H64V,V68A)-catalyzed cyclopropanation were investigated via a combination of crystallographic, computational (DFT), and structure-activity analyses. Our results show the importance of steric complementarity and noncovalent interactions involving first-sphere active site residues, heme-carbene, and the olefin substrate in dictating the stereochemical outcome of the cyclopropanation reaction. High stereocontrol is achieved through two major mechanisms: first, by enforcing a specific conformation of the heme-bound carbene within the active site, and second, by controlling the geometry of attack of the olefin on the carbene via steric occlusion, attractive van der Waals forces, and protein-mediated π-π interactions with the olefin substrate. These insights could be leveraged to expand the substrate scope of the myoglobin-based cyclopropanation catalyst toward nonactivated olefins and to increase its cyclopropanation activity in the presence of a bulky α-diazo-ester. This work sheds light on the origin of enzyme-catalyzed enantioselective cyclopropanation, furnishing a mechanistic framework for both understanding the reactivity of current systems and guiding the future development of biological catalysts for this class of synthetically important, abiotic transformations.
- Tinoco, Antonio,Wei, Yang,Bacik, John-Paul,Carminati, Daniela M.,Moore, Eric J.,Ando, Nozomi,Zhang, Yong,Fasan, Rudi
-
p. 1514 - 1524
(2019/02/03)
-
- Iron and Ruthenium Glycoporphyrins: Active Catalysts for the Synthesis of Cyclopropanes and Aziridines
-
In view of the relevance of cyclopropanes and aziridines as synthetic building blocks as well as active parts in biological and pharmaceutical compounds, the development of sustainable synthetic procedures for obtaining these products continues to be a si
- Damiano, Caterina,Gadolini, Sebastiano,Intrieri, Daniela,Lay, Luigi,Colombo, Cinzia,Gallo, Emma
-
p. 4412 - 4420
(2019/11/03)
-
- Iron-catalyzed synthesis of cyclopropanes by in situ generation and decomposition of electronically diversified diazo compounds
-
The modular synthesis of a variety of trans 1,2-disubstituted cyclopropanes in a safe and user-friendly one-pot iron-catalyzed cyclopropanation reaction is described. Easily synthesized N-nosylhydrazones are used as diazo precursors, allowing the in situ generation of electron-rich diazo compounds under mild reaction conditions and their direct participation in the cyclopropanation reaction.
- Allouche, Emmanuelle M. D.,Al-Saleh, Afnan,Charette, André B.
-
p. 13256 - 13259
(2018/12/11)
-
- Interfacing Microbial Styrene Production with a Biocompatible Cyclopropanation Reaction
-
Abstract The introduction of new reactivity into living organisms is a major challenge in synthetic biology. Despite an increasing interest in both the development of small-molecule catalysts that are compatible with aqueous media and the engineering of enzymes to perform new chemistry in vitro, the integration of non-native reactivity into metabolic pathways for small-molecule production has been underexplored. Herein we report a biocompatible iron(III) phthalocyanine catalyst capable of efficient olefin cyclopropanation in the presence of a living microorganism. By interfacing this catalyst with E.coli engineered to produce styrene, we synthesized non-natural phenyl cyclopropanes directly from D-glucose in single-vessel fermentations. This process is the first example of the combination of nonbiological carbene-transfer reactivity with cellular metabolism for small-molecule production.
- Wallace, Stephen,Balskus, Emily P.
-
supporting information
p. 7106 - 7109
(2015/06/08)
-
- Highly diastereoselective and enantioselective olefin cyclopropanation using engineered myoglobin-based catalysts
-
Using rational design, an engineered myoglobinbased catalyst capable of catalyzing the cyclopropanation of aryl-substituted olefins with catalytic proficiency (up to 46800 turnovers) and excellent diastereo- and enantioselectivity (98-99.9%) was developed. This transformation could be carried out in the presence of up to 20 gL-1 olefin substrate with no loss in diastereo- and/or enantioselectivity. Mutagenesis and mechanistic studies support a cyclopropanation mechanism mediated by an electrophilic, heme-bound carbene species and a model is provided to rationalize the stereopreference of the protein catalyst. This work shows that myoglobin constitutes a promising and robust scaffold for the development of biocatalysts with carbene-transfer reactivity.
- Bordeaux, Melanie,Tyagi, Vikas,Fasan, Rudi
-
p. 1744 - 1748
(2015/02/19)
-
- Encapsulated cobalt-porphyrin as a catalyst for size-selective radical-type cyclopropanation reactions
-
A cobalt-porphyrin catalyst encapsulated in a cubic M8L 6 cage allows cyclopropanation reactions in aqueous media. The caged-catalyst shows enhanced activities in acetone/water as compared to pure acetone. Interestingly, the M8L6 encapsulated catalyst reveals size-selectivity. Smaller substrates more easily penetrate through the pores of the "molecular ship-in-a-bottle catalysts" and are hence converted faster than bigger substrates. In addition, N-tosylhydrazone sodium salts are easy to handle reagents for cyclopropanation reactions under these conditions.
- Otte, Matthias,Kuijpers, Petrus F.,Troeppner, Oliver,Ivanovic-Burmazovic, Ivana,Reek, Joost N. H.,De Bruin, Bas
-
supporting information
p. 4880 - 4884
(2014/05/06)
-
- Conformational restriction approach to β-secretase (BACE1) inhibitors III: Effective investigation of the binding mode by combinational use of X-ray analysis, isothermal titration calorimetry and theoretical calculations
-
For further investigation of BACE1 inhibitors using conformational restriction with sp3 hybridized carbon, we applied this approach to 6-substituted aminopyrimidone derivatives 3 to improve the inhibitory activity by reducing the entropic energy loss upon binding to BACE1. Among eight stereoisomers synthesized, [trans-(1′R,2′R),6S] isomer 6 exhibited the best BACE1 inhibitory activity, which was statistically superior to that of the corresponding ethylene linker compound (R)-3. Combinational examinations of the binding mode of 6 were performed, which included isothermal titration calorimetry (ITC), X-ray crystallographic structure analysis and theoretical calculations, to clarify the effect of our conformational restriction approach. From the ITC measurement, the binding entropy of 6 was found to be ~0.5 kcal larger than that of (R)-3, which is considered to be affected by conformational restriction with a cyclopropane ring.
- Yonezawa, Shuji,Fujiwara, Kenichiro,Yamamoto, Takahiko,Hattori, Kazunari,Yamakawa, Hidekuni,Muto, Chie,Hosono, Motoko,Tanaka, Yoshikazu,Nakano, Toru,Takemoto, Hiroshi,Arisawa, Mitsuhiro,Shuto, Satoshi
-
supporting information
p. 6506 - 6522
(2013/10/22)
-
- Highly enantioselective intermolecular carbene insertion to C-H and Si-H bonds catalyzed by a chiral iridium(iii) complex of a D4-symmetric Halterman porphyrin ligand
-
The chiral iridium porphyrin [Ir((-)-D4-Por*)(Me)(EtOH)] displays excellent reactivity and stereoselectivity towards carbene insertion to C-H and Si-H bonds, affording corresponding products in high yields (up to 96%) and high enantioselectivities (up to 98% ee). The Royal Society of Chemistry 2012.
- Wang, Jing-Cui,Xu, Zhen-Jiang,Guo, Zhen,Deng, Qing-Hai,Zhou, Cong-Ying,Wan, Xiao-Long,Che, Chi-Ming
-
supporting information; experimental part
p. 4299 - 4301
(2012/05/20)
-
- Highly cis -selective Rh(I)-catalyzed cyclopropanation reactions
-
The performance of recently reported highly cis-diastereoselective Rh(I) cyclopropanation catalysts has been significantly improved by a systematic study of different reaction parameters (catalyst activation, solvent, temperature, stoichiometry). The cata
- Rosenberg, Marianne Lenes,Vlasana, Klara,Gupta, Nalinava Sen,Wragg, David,Tilset, Mats
-
experimental part
p. 2465 - 2470
(2011/06/24)
-
- Asymmetric synthesis of di- and trisubstituted cyclopropanes through an intramolecular ring closure
-
An asymmetric synthesis of di- and trisubstituted cyclopropanes proceeding through an intramolecular ring closure of activated chiral benzyl alcohols has been developed. The chiral alcohol intermediates are obtained from asymmetric reduction of readily av
- Kallemeyn, Jeffrey M.,Mulhern, Mathew M.,Ku, Yi-Yin
-
p. 535 - 538
(2011/05/04)
-
- Cyclopropanation of olefins with diazo compounds catalyzed by a dicopper-substituted silicotungstate [γ-H2SiW 10O36Cu2(μ-1,1-N3) 2]4-
-
The dicopper-substituted γ-Keggin silicotungstate (TBA) 4[γ-H2SiW10O36Cu 2II(μ-1,1-N3)2] (I, TBA = tetra-n-butylammonium) could act as an efficient precatalyst for the chemoselective cylopropanation of olefins with diazo compounds. Various kinds of olefins were efficiently converted to the corresponding cyclopropane derivatives in good yields.
- Kamata, Keigo,Kimura, Toshihiro,Mizuno, Noritaka
-
supporting information; experimental part
p. 702 - 703
(2011/01/08)
-
- Chiral bis(oxazolinyl)phenyl RuII catalysts for highly enantioselective cyclopropanation
-
chemical equation presantation Good to excellent enantioselectivities (up to 99 % ee) of trans-cyclopropane derivatives were achieved in the cyclopropanation of alkenes with tert-buty1 α-diazoacetate by using 0.5 mol % of a mononuclear chiral ruthenium aqua complex containing the chiral bis(oxazolinyl)phenyl ligand, which was obtained via C-H activation by RuCl 3·3H2O in the presence of Mg and cyclooctadiene (cod). Intramolecular cyclopropanation reactions using the new Ru complex also proceed with high yields and excellent enantioselectivities.
- Ito, Jun-Ichi,Ujiie, Satoshi,Nishiyama, Hisao
-
experimental part
p. 4986 - 4990
(2010/08/19)
-
- Chiral C1-symmetric 2,2′:6′,2′′-terpyridine ligands: Synthesis, characterization, complexation with copper(II), rhodium(III) and ruthenium(II) ions and use of the complexes in catalytic cyclopropanation of styrene
-
Three new optically pure C1-terpyridine ligands (L1-3) were prepared and the copper(II) complexes, of formula [Cu(L)Cl2], the rhodium(III) complexes, of formula [Rh(L)Cl3], and the ruthenium(II) complexes, of formula cis-
- Yeung, Chi-Tung,Lee, Wing-Sze,Tsang, Chui-Shan,Yiu, Shek-Man,Wong, Wing-Tak,Wong, Wai-Yeung,Kwong, Hoi-Lun
-
experimental part
p. 1497 - 1507
(2010/05/01)
-
- Cu and Au metal-organic frameworks bridge the gap between homogeneous and heterogeneous catalysts for alkene cyclopropanation reactions
-
The copper and gold metal-organic frameworks (MOFs) [Cu3(BTC) 2(H2O)3]n, [Cu3(BTC) 2] (BTC = benzene-1,3,5-tricarboxylate), and IRMOF-3-SI-Au are active and reusable solid catalysts for the cyclopropanation of alkenes with high chemo- and diastereoselectivities. This type of material gives better results than previous solid catalysts while working together with the homogeneous catalysts. These MOFs can help to bridge the gap between homogeneous and heterogeneous catalysis.
- Corma, Avelino,Iglesias, Marta,Llabres i Xamena, Francesc X.,Sanchez, Felix
-
experimental part
p. 9789 - 9795
(2010/11/02)
-
- Sweets for catalysis - Facile optimisation of carbohydrate-based bis(oxazoline) ligands
-
A new type of carbohydrate-based bis(oxazoline) ligands was prepared from inexpensive D-glucosamine and tested in asymmetric cyclopropanation reactions. For optimisation, modified ligands with 3-O substituents of varying size and electronic properties were prepared as well as a 3-OH unprotected and a perpivaloylated derivative. All new ligands were tested in asymmetric cyclopropanation, revealing a strong dependence of enantioselectivity on steric demand and electronic properties of the 3-O residue. Also, a significant influence of the pyranose conformation, which is determined by the presence or absence of the cyclic acetal group, was observed. Thus, it was easily possible to tune the new carbohydrate bis(oxazoline) ligands to a given reaction.
- Minuth, Tobias,Irmak, Mustafa,Groschner, Annika,Lehnert, Tobias,Boysen, Mike M. K.
-
experimental part
p. 997 - 1008
(2009/07/19)
-
- Azaarene cis-dihydrodiol-derived 2,2′-bipyridine ligands for asymmetric allylic oxidation and cyclopropanation
-
Biphenyl dioxygenase-catalysed cis-dihydroxylation of 2-chloroquinoline, 2-chloro-3-methylquinoline and 2-chloro-6-phenylpyridine substrates yielded the corresponding enantiopure cis-dihydrodiols; enantiopure 2,2′-bipyridines, synthesised in four steps fr
- Boyd, Derek R.,Sharma, Narain D.,Sbircea, Lenuta,Murphy, Deirdre,Belhocine, Tayeb,Malone, John F.,James, Stuart L.,Allen, Christopher C. R.,Hamilton, John T. G.
-
supporting information; experimental part
p. 5535 - 5537
(2009/04/12)
-
- Construction of aryliridium-salen complexes: Enantio- and cis-selective cyclopropanation of conjugated and nonconjugated olefins
-
Two stable and optically active iridium-salen complexes were synthesized by introducing a tolyl or phenyl ligand at the apical position, respectively, via the SEAr mechanism, and they were found to be efficient catalysts for cis-selective asymm
- Suematsu, Hidehiro,Kanchiku, Shigefumi,Uchida, Tatsuya,Katsuki, Tsutomu
-
experimental part
p. 10327 - 10337
(2009/02/04)
-
- Surface confinement effects in enantioselective catalysis: Design of new heterogeneous chiral catalysts based on C1-symmetric bisoxazolines and their application in cyclopropanation reactions
-
Surface confinement effects are extremely important in determining the stereochemical course of cyclopropanation reactions catalyzed by C2-symmetric bisoxazoline-copper complexes immobilized on laponite. In the case of the PhBox ligand, complete reversal of trans/cis-diastereoselectivity is observed, as well as a reversal in the absolute configuration of the major cis-cyclopropane. Furthermore, the enantioselectivity obtained with the immobilized catalyst is better than that obtained in the homogeneous phase, indicating that support effects can be beneficial to the stereoselectivity of the reaction. The design of C1-symmetric bisoxazoline ligands specifically for heterogeneous catalysis allows improvement of the cis-selectivity of the benchmark cyclopropanation reaction up to 91% cis-cyclopropanes. This finding is in agreement with a closer complex surface approach. Experiments carried out with reagents with a greater steric demand highlight the existence of reaction channels in which the ester group points toward the support surface, a factor that was disregarded in the former stereoinduction model.
- Garcia, Jose I.,Lopez-Sanchez, Beatriz,Mayoral, Jose A.,Pires, Elisabet,Villalba, Isabel
-
experimental part
p. 378 - 385
(2009/03/11)
-
- Preparation of new axially chiral bridged 2,2′-bipyridines and pyridyl monooxazolines (pymox). Evaluation in copper(i)-catalyzed enantioselective cyclopropanation
-
This work reports the synthesis of new axially chiral bridged 2,2′-bipyridines 1 and pyridylmonooxazolines (pymox) 2. The potential of these new axially chiral N,N-ligands was evaluated in asymmetric catalytic cyclopropanation of styrene derivatives 22a-c with diazoesters 21a,b. While 2,2′-bipyridines 1a-c afforded the corresponding cyclopropanes 23a-f in up to 65% ee, pymoxs 2a-e gave somewhat lower enantioselectivities (up to 53% ee). Both classes of ligands produced trans-cyclopropanes 23a-f as the major isomer, although with modest diasteroselectivities (56: 44 to 78: 22). A structure-stereoselectivity relationship study of ligands 1 and 2 identified the chiral biaryl axis as being mostly responsible for the enantioselective performances of these ligands. The Royal Society of Chemistry.
- Bouet, Alexis,Heller, Barbara,Papamicael, Cyril,Dupas, Georges,Oudeyer, Sylvain,Marsais, Francis,Levacher, Vincent
-
p. 1397 - 1404
(2007/12/27)
-
- Construction of an aryliridium-salen complex for highly cis- and enantioselective cyclopropanations
-
(Chemical Equation Presented) Ringing the changes: Iridium(lll)-salen complexes 1 bearing a σ-coordinated aryl ligand (L = CH3C 6H4, C6H5) at the apical position are found to efficiently catalyze the cis- and enantioselective cyclopropanation of mono- and disubstituted olefins (see scheme).
- Kanchiku, Shigefumi,Suematsu, Hidehiro,Matsumoto, Kazuhiro,Uchida, Tatsuya,Katsuki, Tsutomu
-
p. 3889 - 3891
(2008/02/14)
-
- Asymmetric cyclopropanation catalyzed by fluorous bis(oxazolines)-copper complexes
-
Fluorous bis(oxazoline)-copper(I) complexes generated in situ were tested as catalysts in the metal-catalyzed cyclopropanation of styrene with various α-diazoacetates. Under optimized conditions in CH2Cl2, quite good yields were obta
- Bayardon, Jerome,Holczknecht, Orsolya,Pozzi, Gianluca,Sinou, Denis
-
p. 1568 - 1572
(2007/10/03)
-
- Trans effect on cobalt porphyrin catalyzed asymmetric cyclopropanation
-
A significant trans effect of potential coordinating additives was found in asymmetric cyclopropanation catalyzed by Co(II) complexes of D 2-symmetric chiral porphyrins [Co(1)]. Among different additives, substoichiometric amounts of DMAP resul
- Chen, Ying,Zhang, X. Peter
-
p. 1697 - 1700
(2007/10/03)
-
- α-diazoacetates as carbene precursors: Metallosalen-catalyzed asymmetric cyclopropanation
-
Readily available α-diazo compounds have been shown to be efficient carbene precursors for asymmetric cyclopropanation using ruthenium(NO)-salen and cobalt-salen complexes, as catalysts. The stereoselectivity of the cyclopropanation depends on the metal i
- Uchida, Tatsuya,Katsuki, Tsutomu
-
p. 1715 - 1723
(2007/10/03)
-
- Concave 1,10-phenanthrolines as tailored ligands for copper(I)-catalyzed diastereoselective cyclopropanations
-
Alkenyloxy-substituted aryl bridgeheads have been connected to 2,9-dichloro-1,10-phenanthroline (11) either by Suzuki coupling or by nucleophilic aromatic substitution. The resulting di- or tetraalkenes 12 or 17 have been cyclized by ring-closing metathesis to give concave 1,10-phenanthrolines 14 and 19, differing from other concave 1,10-phenanthrolines 1 in their geometries. The influence of the shapes of these ligands and those of the related concave 1,10-phenanthrolines 1a-f and 2 on the stereochemistry of the copper(I)-catalyzed cyclopropanation of indene (3) and styrene (4) has been investigated, identifying factors that favour the formation of thermodynamically less stable syn-cyclopropanes 6 and 7. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Luening, Ulrich,Fahrenkrug, Frank
-
p. 916 - 923
(2007/10/03)
-
- Chiral porphyrins, chiral metalloporphyrins, and methods for synthesis of the same
-
Novel methods of synthesizing heteroatom-containing chiral porphyrins and chiral metalloporphyrins and the novel chiral porphyrins and chiral metalloporphyrins themselves are disclosed. Metal complexes of the chiral porphyrins are prepared in high yields and shown to be active catalysts for highly enantioselective and diastereoselective cyclopropanation, aziridination, and epoxidation of alkenes under a practical one-pot protocol.
- -
-
-
- Synthesis of novel chiral semicrown ether-like bis(oxazoline) ligands and application in enantioselective cyclopropanation of styrene
-
A series of chiral C2-symmetric bis(oxazoline) ligands containing semicrown ether unit were synthesized. The copper complexes prepared in situ from copper(I)-triflate, and the new chiral oxazoline ligands were assessed as chiral catalysts in th
- Wang, Zhan-Yue,Du, Da-Ming,Xu, Jia-Xi
-
p. 299 - 313
(2007/10/03)
-
- Chiral boron-bridged bisoxazolines: Readily available anionic ligands for asymmetric catalysis
-
Asymmetric cyclopropanation and monobenzoylation reactions of mesa diols employing borabox catalysts 1 (M = Cu) result in high enantioselectivities. The borabox ligands are anionic analogues of the bisoxazolines 2 and are readily prepared by lithiation of
- Mazet, Clement,Koehler, Valentin,Pfaltz, Andreas
-
p. 4888 - 4891
(2007/10/03)
-
- C2-symmetric fluorous diamines and diimines as ligands for metal-catalysed asymmetric cyclopropanation of styrene
-
Perfluoroalkyl-substituted, enantiopure C2-symmetric N and N,O ligands showing affinity either for standard organic solvents or perfluorocarbons have been conveniently prepared from readily available precursors. Preformed cobalt(II) and in-situ-generated copper(I) complexes of these ligands were tested as catalysts in the metal-catalysed cyclopropanation of styrene with diazoacetates. Under optimised reaction conditions, which include the use of a fluorous biphasic system and short reaction times, the copper complex of a C2-symmetric diamine afforded promising results (yield = 77%, trans/cis = 67:33, ee of the trans isomer = 62%) and could be easily separated from the products by simply decanting the fluorous phase. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Shepperson, Ian,Quici, Silvio,Pozzi, Gianluca,Nicoletti, Marcello,O'Hagan, David
-
p. 4545 - 4551
(2007/10/03)
-
- Bromoporphyrins as versatile synthons for modular construction of chiral porphyrins: Cobalt-catalyzed highly enantioselective and diastereoselective cyclopropanation
-
5,10-Bis(2′,6′-dibromophenyl)porphyrins bearing various substituents at the 10 and 20 positions were demonstrated to be versatile synthons for modular construction of chiral porphyrins via palladium-catalyzed amidation reactions with chiral amides. The quadruple carbon-nitrogen bond formation reactions were accomplished in high yields with different chiral amide building blocks under mild conditions, forming a family of D2-symmetric chiral porphyrins. Cobalt(II) complexes of these chiral porphyrins were prepared in high yields and shown to be active catalysts for highly enantioselective and diastereoselective cyclopropanation under a practical one-pot protocol (alkenes as limiting reagents and no slow addition of diazo reagents). Copyright
- Chen, Ying,Fields, Kimberly B.,Zhang, X. Peter
-
p. 14718 - 14719
(2007/10/03)
-
- Synthesis of a new chiral nonracemic C2-symmetric 2,2′-bipyridyl ligand and its application in copper(I)-catalyzed enantioselective cyclopropanation reactions
-
An efficient synthesis of a low molecular weight, chiral nonracemic and (C2-symmetric bipyridyl ligand is reported. The ligand was prepared using a catalytic asymmetric dihydroxylation reaction of a pyrindine as a key step. The ligand was evalu
- Lyle, Michael P. A.,Wilson, Peter D.
-
p. 855 - 857
(2007/10/03)
-
- Synthesis of new chiral 2,2′-bipyridine ligands and their application in Copper-catalyzed asymmetric allylic oxidation and cyclopropanation
-
A series of modular bipyridine-type ligands 1 and 3-9 has been synthesized via a de novo construction of the pyridine nucleus. The chiral moieties of these ligands originate from the isoprenoid chiral pool, namely, β-pinene (10 → 1), 3-carene (14 → 3 and 5), 2-carene (28 → 4), α-pinene (43 → 6-8), and dehydropregnenolone acetate (48 → 9), respectively. Copper(I) complexes, derived from these ligands and (TfO)2Cu (1 mol%) upon an in situ reduction with phenylhydrazine, exhibit good enantioselectivity (up to 82% ee) and unusually high reaction rate (typicaly 30 min at room temperature) in allylic oxidation of cyclic olefins (52 → 53). Copper-catalyzed cyclopropanation proceeded with ≤76% enantioselectivity and ~3:1 to 99:1 trans/cis-diastereoselectivity (54 → 55 + 56). The level of the asymmetric induction is discussed in terms of the ligand architecture that controls the stereochemical environment of the coordinated metal.
- Malkov, Andrei V.,Pernazza, Daniele,Bell, Mark,Bella, Marco,Massa, Antonio,Teply, Filip,Meghani, Premji,Kocovsky, Pavel
-
p. 4727 - 4742
(2007/10/03)
-
- Chiral catalysts confined in porous hosts 2. Catalysis
-
The catalytic activities of the dirhodium carboxamide catalysts immobilized in the pores of MCM-41 and on the surface of Aerosil 200 were studied. The catalysts were tested in the Si-H insertion reaction of dimethylphenylsilane with methyl phenyl diazoace
- Hultman, Heidi M.,De Lang, Martine,Arends, Isabel W.C.E.,Hanefeld, Ulf,Sheldon, Roger A.,Maschmeyer, Thomas
-
p. 275 - 283
(2007/10/03)
-
- Novel chiral dibenzo[a,c]cycloheptadiene bis(oxazoline) and catalytic enantioselective cyclopropanation of styrene
-
A series of chiral C2-symmetric bis(oxazoline) ligands containing dibenzo[a,c]cycloheptadiene units were synthesized. The copper complexes, prepared in situ from copper (I)-triflate and the new enantiopure oxazoline ligands, were assessed as chiral catalysts in the enantioselective cyclopropanation of styrene with diazoacetate. Enantioselectivities up to 82 and 62%, respectively, for trans- and cis-2-phenylcyclopropanecarboxylate were observed.
- Du, Da-Ming,Fu, Bin,Hua, Wen-Ting
-
p. 1933 - 1938
(2007/10/03)
-
- In search of high stereocontrol for the construction of cis-disubstituted cyclopropane compounds. Total synthesis of a cyclopropane-configured urea-PETT analogue that is a HIV-1 reverse transcriptase inhibitor.
-
[reaction: see text] A new azetidine-ligated dirhodium(II) catalyst that possesses a l-menthyl ester attachment provides significant diastereocontrol and high enantiocontrol for the formation of cis-cyclopropane products from reactions of substituted styr
- Hu, Wenhao,Timmons, Daren J,Doyle, Michael P
-
p. 901 - 904
(2007/10/03)
-
- A new chiral ruthenium complex for catalytic asymmetric cyclopropanation
-
A new chiral ruthenium complex 6, featured with an N,O-mixed polydentate ligand, was synthesized and characterized. This ruthenium complex showed high efficiency in catalytic cyclopropanations of alkenes with diazoacetates. High trans/cis selectivity and enantioselectivity (up to 96%) were achieved with the readily accessible ethyl diazoacetate as the reagent.
- Tang, Wenjun,Hu, Xinquan,Zhang, Xumu
-
p. 3075 - 3078
(2007/10/03)
-
- Copper complexes of chiral tetradentate binaphthyl Schiff-base ligands: Syntheses, X-ray crystal structures and activity in catalytic asymmetric cyclopropanation of alkenes
-
A number of new chiral monomeric binaphthyl Schiff-base ligands H2L [where H2L = 2,2′-bis(3-R1-5-R2-2-hydroxybenzylideneamino) -1,1′-binaphthyl] and a series of chiral copper(II) complexes [CuL] were prepared in good or nearly quantitative yields. Some of the free ligands and the [CuL] complexes were structurally characterized by X-ray crystallography. Almost all the [CuL] complexes were found to be active catalysts for the asymmetric cyclopropanation of alkenes with ethyl or tert-butyl diazoacetate. Enantioselectivities of up to 77% ee were observed. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
- Che, Chi-Ming,Kwong, Hoi-Lun,Chu, Wai-Cheung,Cheng, Kin-Fai,Lee, Wing-Sze,Yu, Hing-Sun,Yeung, Chi-Tung,Cheung, Keung-Kai
-
p. 1456 - 1463
(2007/10/03)
-
- A modular approach to C1 and C3 chiral N-tripodal ligands for asymmetric catalysis
-
A new class of tripodal ligands, chiral 1,1,1-tris(oxazolinyl)ethane derivatives, has been synthesized by using a modular approach by coupling of mono- with bisoxazoline derivatives. This method allows the facile access to symmetrically (C3-chi
- Bellemin-Laponnaz, Stephane,Gade, Lutz H.
-
p. 3473 - 3475
(2007/10/03)
-
- From homogeneous to heterogeneous catalysis: Zeolite supported metal complexes with C2-multidenate nitrogen ligands. Application as catalysts for olefin hydrogenation and cyclopropanation reactions
-
The fixation of the preformed rhodium and copper complexes, {[Rh(N,N′-bis[(S)-prolyl-N-(2-aminoethyl-3-aminopropyl) triethoxysilyl]ethylenediamine)(THF)]X, [Rh((N,N′-bis[(S)-benzyl X = PF6}, {[Cu(N,N′-bis[(S)-prolyl-N- (2-aminoethyl-3-aminoprop
- Alcón,Corma,Iglesias, Marta,Sánchez
-
p. 134 - 145
(2007/10/03)
-
- Asymmetric inter- and intramolecular cyclopropanation of alkenes catalyzed by chiral ruthenium porphyrins. Synthesis and crystal structure of a chiral metalloporphyrin carbene complex
-
Extensive investigations of asymmetric intermolecular cyclopropanation of terminal alkenes with diazoacetates catalyzed by ruthenium porphyrin [Ru(P*)(CO)(EtOH)] (1, H2P* = 5,10,15,20-tetrakis-{(1S,4R,5R,8S)-1,2,3,4,5,6,7,8-octahydro-1,4:5,8- dimethanoanthracene-9-yl}porphyrin) and the application of catalyst 1 to asymmetric intramolecular cyclopropanation of allylic or homoallylic diazoacetates are described. The intermolecular cyclopropanation of styrene and its derivatives with ethyl diazoacetate afforded the corresponding cyclopropyl esters in up to 98% ee with high trans/cis ratios of up to 36 and extremely high catalyst turnovers of up to 1.1 × 104. Examination of the effects of temperature, diazoacetate, solvent, and substituent in the intermolecular cyclopropanation reveals that (i) both enantioselectivity and trans selectivity increase with decreasing temperature, (ii) sterically encumbered diazoacetates N2CHCO2R such as R = But, and donor solvents, such as diethyl ether and tetrahydrofuran, are beneficial to the trans selectivity, and (iii) electron-donating para substituents on styrene accelerate the cyclopropanations, with the log(kx/kH) vs σ+ plot for para-substituted styrenes p-X-C6H4CH=CH2 (X = MeO, Me, Cl, CF3) exhibiting good linearity with a small negative ρ+ value of -0.44 ± 0.09. In the case of intramolecular cyclopropanation, complex 1 promoted the decomposition of a series of allylic diazoacetates to form the cyclopropyl lactones in up to 85% ee, contributing the first efficient metalloporphyrin catalyst for an asymmetric intramolecular cyclopropanation. Both the inter- and intramolecular cyclopropanations were proposed to proceed via a reactive chiral ruthenium carbene intermediate. The enantioselectivities in these processes were rationalized on the basis of the X-ray crystal structures of closely related stable chiral carbene complexes [Ru(P*)(CPh2)] (2) and [Ru(P*)(C(Ph)-CO2CH2CH=CH2)] (3) obtained from reactions of complex 1 with N2CPh2 and N2C(Ph)CO2CH2CH=CH2, respectively.
- Che,Huang,Lee,Li,Lai,Kwong,Teng,Lee,Lo,Peng,Zhou
-
p. 4119 - 4129
(2007/10/03)
-
- Highly Enantioselective Cyclopropanation with Co(II)-Salen Complexes: Control of cis- and trans-Selectivity by Rational Ligand-Design
-
Cyclopropanation of styrene derivatives with alkyl α-diazoacetate in the presence of the second-generation (salen)cobalt(II) complex 6 proceeded with excellent cis- and enantioselectivity. On the other hand, the cyclopropanation in the presence of complex 14 which was designed on the basis of the mechanism of asymmetric induction by complex 6 showed good trans- and excellent enantio-selectivity.
- Niimi, Tatsuo,Uchida, Tatsuya,Irie, Ryo,Katsuki, Tsutomu
-
-
- Highly enantioselective cyclopropanation of styrenes and diazoacetates catalyzed by 3-oxobutylideneaminatocobalt(II) complexes, part 1. Designs of cobalt complex catalysts and the effects of donating ligands
-
Highly enantioselective cyclopropanation of styrene derivatives and diazoacetates was effectively catalyzed by reasonably designed 3-oxobutylideneaminatocobalt(II) complexes, whose ligands were prepared from 1,2-dimesitylethyl-enediamine and alkyl 3-oxobutanoates. The steric demand of the diamine unit of the complexes seriously influenced the enantioselectivity, and the ester groups on their side chains somewhat improved the trans-selectivity. Addition of a catalytic amount of N-methylimidazole significantly accelerated the reaction and enhanced the enantioselectivity due to its coordination to the center cobalt atom of the complex as an axial ligand. Alcoholic or aqueous alcoholic solvents were also effective particularly for the cyclopropanation of 1-substituted 1-phenylethylenes to achieve high enantioselectivity in aqueous methanol.
- Ikeno, Taketo,Sato, Mitsuo,Sekino, Hiroyuki,Nishizuka, Asae,Yamada, Tohru
-
p. 2139 - 2150
(2007/10/03)
-
- cis- and enantio-selective cyclopropanation with chiral (ON+)Ru-salen complex as a catalyst
-
Cyclopropanation of styrene with α-diazoacetate in the presence of (R,R)-(salen)ruthenium complex 4 in THF which dissolves the complex exhibits remarkable cis- and enantio-selectivity [cis:trans=97:3, >97% ee (1S,2R)], while the same reaction in hexane which does not dissolve it shows good but opposite sense of enantioselectivity [-83% ee (1R,2S)] together with moderate cis-selectivity (cis:trans=68:32). In homogeneous and heterogeneous conditions, (salen)ruthenium complexes are considered to have different ligand-conformation which, in turn, causes the opposite sense of enantioface selectivity in the cyclopropanation. 2000 Elsevier Science Ltd.
- Uchida, Tatsuya,Irie, Ryo,Katsuki, Tsutomu
-
p. 3501 - 3509
(2007/10/03)
-
- Co(II)-salen-catalyzed highly cis- and enantioselective cyclopropanation
-
The reactions of styrene derivatives and t-butyl α-diazoacetate using (R,R)-(salen)cobalt(II) complex 6 as a catalyst in the presence of N- methylimidazole gave the corresponding cyclopropanecarboxylates with excellent enantio- (>95% ee) and high cis-ster
- Niimi, Tatsuo,Uchida, Tatsuya,Irie, Ryo,Katsuki, Tsutomu
-
p. 3647 - 3651
(2007/10/03)
-
- cis-Selective cyclopropanations using chiral 5,5-diaryl bis(oxazoline) catalysts
-
A series of 5,5-diaryl bis(oxazolines) have been prepared and used as ligands in the copper catalysed asymmetric cyclopropanation of styrene. Unusually, for bis(oxazolines), the diastereoselectivity of the process favoured the cis cyclopropanes with diastereomeric ratios of up to 65:35 being realised. The cis selectivity of the process was rationalised in terms of repulsion between the alkene substituent and the pro-R 5-aryl group of the bis(oxazoline). (C) 2000 Published by Elsevier Science Ltd.
- Alexander,Cook,Gibson
-
p. 7135 - 7138
(2007/10/03)
-
- Chiral ligands with pyridine donors in transition metal catalyzed enantioselective cyclopropanation and hydrosilylation reactions
-
Copper(I) and rhodium(I) complexes prepared in situ from [Cu(OTf)(C6H6)0.5] and [Rh(cod)Cl]2 with a range of chiral 2,2'-bipyridines, 5,6-dihydro-1,10-phenanthrolines, 1,10-phenanthrolines and 2,2':6',2''-terpyridines were assessed as chiral catalysts for the enantioselective cyclopropanation of styrene with diazoacetates and for the hydrosilylation of acetophenone with diphenylsilane. Enantioselectivities up to 68% in the cyclopropanation and up to 32% in the hydrosilylation were obtained. Copyright (C) 2000 Elsevier Science Ltd.
- Chelucci, Giorgio,Gladiali, Serafino,Sanna, Maria G.,Brunner, Henri
-
p. 3419 - 3426
(2007/10/03)
-
- First enantioselective catalyst based on a chiral terpyridine: Synthesis of new C2-symmetric 2,2':6',2''-terpyridine ligands and copper-catalyzed enantioselective cyclopropanation of alkenes
-
New C2-symmetric chiral 2,2':6',2''-terpyridines were prepared from readily available homochiral materials. Copper complexes of these ligands were prepared in situ and their catalytic activities in cyclopropanations of alkenes with alkyl diazoacetate to give cyclopropyl esters were studied. In all cases, the cyclopropyl ester yields were excellent and enantioselectivities up to 94% ee were observed. Competition experiments revealed that electron-donating substituents on styrene accelerate the reaction. Hammett plot exhibited a good linearity with negative ρ+ value (-0.79). Copyright (C) 2000 Elsevier Science Ltd.
- Kwong, Hoi-Lun,Lee, Wing-Sze
-
p. 2299 - 2308
(2007/10/03)
-