160497-39-2Relevant academic research and scientific papers
Secondary ligand-metal interactions in rhodium(III) and iridium(III) phosphoramidite complexes
Osswald, Tina,Mikhel, Igor S.,Rüegger, Heinz,Butti, Pietro,Mezzetti, Antonio
, p. 474 - 480 (2010)
The synthesis, characterization, and application in asymmetric catalytic cyclopropanation of Rh(III) and Ir(III) complexes containing (Sa,RC,RC)-O,O′-[1,1′-binaphthyl-2,2′-diyl]-N,N′-bis[1-phenyl-ethyl]phosphoramidite (1) are reported. The X-ray structures of the half-sandwich complexes [MCl2(C5Me5)(1,κP)] (M = Rh, 2a; M = Ir, 2b) show that the metal-phosphoramidite bond is significantly shorter in the Ir(III) analog. Chloride abstraction from 2a (with CF3SO3SiMe3 or with CF3SO3Me) and from 2b (with AgSbF6) gives the cationic species [MCl(C5Me5)(1,2-η-1,κP)]+ (M = Rh, 3a; M = Ir, 3b), which display a secondary interaction between the metal and a dangling phenethyl group (NCH(CH3)Ph) of the phosphoramidite ligand, as indicated by NMR spectroscopic studies. Complexes 3a and 3b slowly decompose in solution. In the case of 3b, the binuclear species [Ir2Cl3(C5Me5)2]+ is slowly formed, as indicated by an X-ray study. Preliminary catalytic tests showed that 3a cyclopropanates styrene with moderate yield (35%) and diastereoselectivity (70:30 trans:cis ratio) and with 32% ee (for the trans isomer).
Silica "sHB" chiral Pc-L* copper complexes for halogen-free solvent cyclopropanation reactions
Castano, Brunilde,Zardi, Paolo,Hoenemann, Yvonne C.,Galarneau, Anne,Gallo, Emma,Psaro, Rinaldo,Caselli, Alessandro,Santo, Vladimiro Dal
, p. 22199 - 22205 (2013)
The grafting of the preformed Pc-L* (pyridine containing macrocyclic ligands) copper(i) complexes on different ordered and non-ordered silicas, and their use, under heterogeneous batch conditions, as catalysts for the olefin cyclopropanation are reported.
Vitamin B12 derivatives as natural asymmetric catalysts: enantioselective cyclopropanation of alkenes.
Chen, Ying,Zhang, X Peter
, p. 2431 - 2435 (2004)
Vitamin B(12) derivatives were found for the first time to be general and efficient catalysts for asymmetric cyclopropanation of alkenes with ethyl diazoacetate (EDA). Among several common derivatives, aquocobalamin (B(12a)) was shown to be the most effec
Semi-Rationally Designed Short Peptides Self-Assemble and Bind Hemin to Promote Cyclopropanation
Korendovych, Ivan V.,Zozulia, Oleksii
supporting information, p. 8108 - 8112 (2020/03/23)
The self-assembly of short peptides gives rise to versatile nanoassemblies capable of promoting efficient catalysis. We have semi-rationally designed a series of seven-residue peptides that form hemin-binding catalytic amyloids to facilitate enantioselect
OPIOID RECEPTOR MODULATORS AND PRODUCTS AND METHODS RELATED THERETO
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Page/Page column 119-120, (2019/10/29)
Compounds are provided having the structure of Formula (I): or a pharmaceutically acceptable isomer, racemate, hydrate, solvate, isotope, or salt thereof, wherein A, B, L, R3, R4, R5, R6, R8, m and n are as defined herein. Such compounds modulate the opioid receptor, particulare the mu-opioid receptor (MOR) and/or the kappa-opioid receptor (KOR), and/or the delta-opioid receptor (DOR). Products containing such compounds, as well as methods for their use and preparation, are also provided.
ARTIFICIAL METALLOENZYMES CONTAINING NOBLE METAL-PORPHYRINS
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Paragraph 0351, (2018/11/21)
The present invention is drawn to artificial metalloenzymes for use in cyclopropanation reactions, amination and C—H insertion.
Continuous flow asymmetric cyclopropanation reactions using Cu(i) complexes of Pc-L* ligands supported on silica as catalysts with carbon dioxide as a carrier
Castano, Brunilde,Gallo, Emma,Cole-Hamilton, David J.,Dal Santo, Vladimiro,Psaro, Rinaldo,Caselli, Alessandro
, p. 3202 - 3209 (2014/06/10)
Continuous flow heterogeneous asymmetric cyclopropanations catalysed by supported hydrogen-bonded (SHB) chiral copper(i) complexes of pyridine containing tetraazamacrocyclic ligands Pc-L* using CO2 as a transport vector are described. The catalytic system showed high stability and good recyclability without loss of activity for at least 24 h in CO2 and catalyst turnover numbers up to 440 were obtained with excellent conversion (up to 99%) and high selectivity (up to 88%). No leaching of copper was observed. Cyclopropane products from both aromatic and aliphatic olefins were obtained in good yields with enantiomeric excesses up to 72%. This journal is the Partner Organisations 2014.
Asymmetric cyclopropanation of olefins catalysed by Cu(i) complexes of chiral pyridine-containing macrocyclic ligands (Pc-L*)
Castano, Brunilde,Guidone, Stefano,Gallo, Emma,Ragaini, Fabio,Casati, Nicola,MacChi, Piero,Sisti, Massimo,Caselli, Alessandro
, p. 2451 - 2462 (2013/03/28)
The synthesis and characterisation of copper(i) complexes of chiral pyridine-containing macrocyclic ligands (Pc-L*) and their use as catalysts in asymmetric cyclopropanation reactions are reported. All ligands and metal complexes were fully characterised, including crystal structures of some species determined by X-ray diffraction on single crystals. This allowed characterising the very different conformations of the macrocycles which could be induced by different substituents or by metal complexation. The strategy adopted for the ligand synthesis is very flexible allowing several structural modifications. A small library of macrocyclic ligands possessing the same donor properties but with either C1 or C2 symmetry was synthesized. Cyclopropane products with both aromatic and aliphatic olefins were obtained in good yields and enantiomeric excesses up to 99%.
Neutral p-cymene ruthenium complexes with P-stereogenic monophosphines. New catalytic precursors in enantioselective transfer hydrogenation and cyclopropanation
Grabulosa, Arnald,Mannu, Alberto,Mezzetti, Antonio,Muller, Guillermo
experimental part, p. 4221 - 4228 (2012/01/13)
A family of eight neutral, pseudotetrahedral piano-stool ruthenium complexes C, of the type [RuCl2(p-cymene)(PArPhR)] (Ar = 1-naphthyl, 9-phenanthryl and 2-biphenylyl; R = Me, i-Pr, OMe, -CH2SiMe 3 and -CH2SiPh3) have been prepared and characterised, including the X-ray crystal structure for C6 (Ar = 2-biphenylyl; R = i-Pr). These complexes catalyse the asymmetric hydrogen transfer reaction of acetophenone in refluxing 2-propanol in the presence of potassium tert-butoxyde, reaching full conversions and up to 45% ee after 24 h towards the S enantiomer of 1-phenylethanol. Cationic complexes formed upon treatment of C with one equivalent of AgSbF6 or (Et3O)PF6 are active in the cyclopropanation reaction of styrene and α-methylstyrene by ethyl diazoacetate. Low to moderate conversions (up to 58%), diastereoselectivities (up to 40% de), and moderate enantioselectivities (up to 69% ee) have been found. For both reactions, bulky complexes and C6 in particular lead to the best results.
Chiral monooxazolines as modular copper(I)-heterocomplex building blocks: Investigations on the catalytic asymmetric cyclopropanation of alkenes
Carreiro, Elisabete P.,Ramalho, J.P. Prates,Burke, Anthony J.
experimental part, p. 4640 - 4648 (2011/07/08)
Novel chiral monodentate oxazoline ligands have been synthesized in good yields. The catalytic activity of these monodentate oxazoline/Cu catalysts was evaluated in the catalytic asymmetric cyclopropanation of styrene and α-methylstyrene, giving moderate to good enantioselectivities (up to 74% ee for the trans-cyclopropane product) and full conversions (up to 100%). In an attempt to enhance the enantioselectivities of the cyclopropanations, heterocombinations of these ligands were used. Unfortunately, with the data set that was used in this study, no improvements were observed. However, to gain an insight into the nature of the active catalyst present under these circumstances, NMR, mass spectrometric and computational studies were carried out and indicated the presence of bidentate heterocomplexes in the equilibrium mixture. Analysis of the stereoselectivities (ees and des) did not prove very useful in pin-pointing the identity of the active chiral catalyst and only afforded a very weak conclusion. In order to ascertain the importance of the π-π interactions, the monodentate oxazoline ligands 3a and 3b were synthesized and screened in these reactions, and the resulting stereoselectivities were compared to the results obtained using ligands 1a and 1b. There seemed to be very weak π-π interactions at work.
