24395-14-0Relevant articles and documents
Cascade reactions of indigo with oxiranes and aziridines: efficient access to dihydropyrazinodiindoles and spiro-oxazocinodiindoles
Butler, Nicholas M.,Hendra, Rudi,Bremner, John B.,Willis, Anthony C.,Lucantoni, Leonardo,Avery, Vicky M.,Keller, Paul A.
, p. 6006 - 6016 (2018)
The base-initiated alkylation of the abundant natural dye indigo 1 with ring-strained electrophiles results in the unprecedented, one-pot synthesis of functionalised dihydropyrazino[1,2-a:4,3-a′]diindoles, dihydroepoxy[1,5]oxazocino[5,4-a:3,2-b′]diindoles, and dihydrodiazepino[1,2-a:4,3-a′]diindoles, resulting from intramolecular ring opening-expansion cyclisation processes of their parent oxiranes and aziridines. Regiochemical and stereochemical aspects of the reactions are reported together with integrated mechanistic proposals. This new indigo cascade chemistry should have broad applicability in the synthesis of chemical architectures, not readily-accessible by other means. The three-step synthesis of the useful synthetic precursor (R)-2-(chloromethyl)-1-tosylaziridine 14 is also described. Initial biological activity investigations into these new 2,2′-dindolyl-based heterocyclic derivatives revealed potent, selective antiplasmodial activity in vitro for several isolated structures, with IC50 values as low as 76.6 nM for (±)-8, while demonstrating low human cell toxicity.
Organocatalytic Olefin Aziridination via Iminium-Catalyzed Nitrene Transfer: Scope, Limitations, and Mechanistic Insight
Johnson, Shea L.,Hilinski, Michael K.
, p. 8589 - 8595 (2019)
Olefin aziridination via organocatalytic nitrene transfer offers potential complementarity to metal-catalyzed methods; however there is a lack of reports of such reactions in the literature. Herein is reported a method that employs an iminium salt to cata
Silver(I) and Copper(I) Complexes of Semi-Bulky Nitrogen-Confused C-Scorpionates
Gardinier, James R.,Jahan, Fathiya,Lindeman, Sergey V.,Meise, Kristen J.,Wang, Denan
, (2020)
Two new sterically demanding nitrogen-confused C-scorpionate ligands with a bis(3,5-diisopropylpyrazol-1-yl)methyl group bound to the 3- position of a normal pyrazole (HLiPr2) or an N-toluenesulfonyl pyrazole (TsLiPr2) have been prepared. Reactions between the ligands (xLiPr2) and silver trifluoromethanesulfonate, AgOTf, gave four new compounds of the types [Ag(xLiPr2)](OTf) (x = Ts, 1a; x = H, 2a) or [Ag(xLiPr2)2](OTf) (x = Ts, 1b; x = H, 2b) depending on the initial metal:ligand ratio. Similarly, the reactions with [Cu(CH3CN)4](PF6) produce four new compounds of the type [Cu(xLiPr2)(CH3CN)](PF6) (x = Ts, 3a; x = H, 4a) or [Cu(xLiPr2)2](PF6) (x = Ts, 3b; x = H, 4b). The solid-state structures of four derivatives (1a·acetone, 3a, 3b·CH2Cl2, and 4b·2THF) were determined by single-crystal X-ray diffraction while all complexes were characterized in CH3CN solution by NMR spectroscopy and ESI(+) MS. The eight new complexes catalyze the aziridination of styrene. The copper complexes were generally (but not exclusively) more active catalysts than their silver counterparts.
Amine-functionalised hexagonal mesoporous silica as support for copper(II) acetylacetonate catalyst
Silva, Ana Rosa,Wilson, Karen,Whitwood, Adrian C.,Clark, James H.,Freire, Cristina
, p. 1275 - 1283 (2006)
Copper(II) acetylacetonate was anchored onto a hexagonal mesoporous silica (HMS) material using a two-step procedure: (i) functionalisation of the surface hydroxy groups with (3-aminopropyl)triethoxysilane (AMPTSi) and then (ii) anchoring of the copper(II) complex through Schiff condensation with free amine groups, using two different metal complex loadings. Upon the first step, nitrogen elemental analysis, XPS and DRIFT showed the presence of amine groups on the surface of the HMS material, and porosimetry indicated that the structure of the mesoporous material remained unchanged, although a slight decrease in surface area was observed. Atomic absorption, XPS and DRIFT showed that copper(II) acetylacetonate was anchored onto the amine-functionalised HMS by Schiff condensation between the free amine groups and the carbonyl groups of the copper(II) complex; using EPR an NO3 coordination sphere was proposed for the anchored copper(II) complex. The new [Cu(acac) 2]-AMPTSi/HMS materials were tested in the aziridination of styrene at room temperature, using PhI=NTs as nitrogen source and acetonitrile as solvent. The styrene conversion and total TON of the heterogeneous phase reaction are higher than those of the same reaction catalysed in homogeneous phase by [Cu(acac)2]; nevertheless, the initial activity decreases and the reaction time increases due to substrate and product diffusion limitations. The heterogeneous catalyst showed a successive slight decrease in catalytic activity when reused for two more times. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
Catalytic aziridination of styrene with copper complexes of substituted 3,7-Diazabicyclo[3.3.1]nonanones
Comba, Peter,Merz, Michael,Pritzkow, Hans
, p. 1711 - 1718 (2003)
The copper(II) complexes of five bispidine-type ligands {3,7- diazabicyclo[3.3.1]nonanone; three tetradentate ligands with 2-pyridyl (L1), 6-methyl-2-pyridyl (L2) or 2-imidazolyl-3-methyl (L3) substituents in 2,4-positions; two pentadentate derivatives of L1 with an additional 2-methylpyridine substituent at N3 (L4) or N7 (L5)} have, with one co-ligand (Cl-), a ligand-enforced square pyramidal (L1,2,3) or octahedral (L4,5) geometry. The main structural properties of three of the five [Cu(L)(Cl)]+ complexes (L1,2,3) are very similar, with Cu-N3 A (trans to N3); with L2 Cu-N3 ～ Cu-N7 and Cu-Cl = 2.22 A (trans to N7); with L5 Cu-N3 A (trans to N7). These structural patterns lead to considerable differences in ligand field and electrochemical properties (range of E° of approx. 500mV), and the reactivities of the copper(II) complexes as aziridination catalysts (styrene, PhINTs, CH3CN) are strikingly different. While the complex with L2 is very efficient, the activities of those with L1 and L3 are reduced to approx. 50% and 30%, respectively, and those with L4 and L5 are inactive. The fact that the maximum TON (maximum turnover number) of CuIIL2 (19) is much smaller than the maximum TON of CuIL2 (47) suggests that in the active form the catalysts are in the CuI oxidation state, and that the differences in reduction potentials are of major importance for catalysis. The result that CuL4,5 have no activity in the CuII state and only a small activity in the reduced form indicates that, apart from the reduction potentials, steric effects might also be of importance. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).
Trispyrazolylborate Ligands Supported on Vinyl Addition Polynorbornenes and Their Copper Derivatives as Recyclable Catalysts
Molina de la Torre, Jesús A.,Pérez-Ortega, Ignacio,Beltrán, álvaro,Rodríguez, Manuel R.,Díaz-Requejo, M. Mar,Pérez, Pedro J.,Albéniz, Ana C.
, p. 556 - 563 (2019)
Polynorbornenes prepared by vinyl addition polymerization and bearing pendant alkenyl groups serve as skeletons to support trispyrazolylborate ligands (Tpx) built at those alkenyl sites. Reaction with CuI in acetonitrile led to VA-PNB–TpxCu(NCMe) (VA-PBN=vinyl addition polynorbornene) with a 0.8–1.4 mmol incorporation of Cu per gram of polymer. The presence of tetracoordinated copper(I) ions was been assessed by FTIR studies on the corresponding VA-PNB-TpxCu(CO) adducts, in agreement with those on discrete TpxCu(CO). The new materials were employed as heterogeneous catalysts in several carbene- and nitrene-transfer reactions, showing a behavior similar to that of the homogeneous counterparts but also being recycled several times maintaining a high degree of activity and selectivity. This is the first example of supported Tpx ligands onto polymeric supports with catalytic applications.
Reaction Chemistry of Silver(I) Trifluoromethanesulfonate Complexes of Nitrogen-Confused C-Scorpionates
Gardinier, James R.,Meise, Kristin J.,Jahan, Fathiya,Lindeman, Sergey V.
, p. 1572 - 1589 (2018)
Two new C-scorpionate ligands with a bis(3,5-dimethylpyrazol-1-yl)methyl group bound to the 3 position of either an N-tosyl (TsL?) or an N-H pyrazole (HL?) ring have been prepared. The silver(I) complexes of these new ligands and the two previously reported analogous ligands with unsubstituted bis(pyrazol-1-yl)methyl groups (TsL and HL) in both 1:1 and 2:1 ligand/metal ratios were investigated to explore the effects of ligand sterics on their physical and chemical properties. The structurally characterized derivatives of the type [Ag(L)2](OTf) are four-coordinate, where the confused pyrazolyl is not bound to the metal. On the other hand, three 1:1 complexes [Ag(L)](OTf) had all pyrazolyls bound, while the μ-κ1,κ1-TsL derivative had an unbound confused pyrazolyl. The molecularity of the latter four ranged from polymeric to dimeric to monomeric in the solid with increasing steric bulk of the ligand. The utility of these complexes in stoichiometric ligand-transfer reactions and in styrene aziridination was demonstrated. Thus, tricarbonylmanganese(I) complexes were prepared as kinetically inert models for comparative solution diffusion NMR studies. Also, [Fe(HL)2](OTf)2 was prepared for similar reasons and to compare the effects of anion on spin-crossover properties.
Fe-Based Complexes as Styrene Aziridination Catalysts: Ligand Substitution Tunes Catalyst Activity
Coin, Guillaume,Patra, Ranjan,Clémancey, Martin,Dubourdeaux, Patrick,Pécaut, Jacques,Lebrun, Colette,Castro, Ludovic,Maldivi, Pascale,Chardon-Noblat, Sylvie,Latour, Jean-Marc
, p. 5296 - 5299 (2019)
As part of our effort to improve our understanding of aziridination mechanism, we used tetra substitution of a diphenol ligand to modify the redox properties of corresponding Fe complexes. This allowed us to confirm that aziridination catalysis by Fe-base
Kinetic Resolution of Aziridines Enabled by N-Heterocyclic Carbene/Copper Cooperative Catalysis: Carbene Dose-Controlled Chemo-Switchability
Zhang, Zi-Jing,Wen, Yu-Hua,Song, Jin,Gong, Liu-Zhu
supporting information, p. 3268 - 3276 (2020/12/14)
Catalytic kinetic resolution (KR) and dynamic kinetic asymmetric transformation (DyKAT) are alternative and complementary avenues to access chiral stereoisomers of both starting materials and reaction products. The development of highly efficient chiral catalytic systems for kinetically controlled processes has therefore been one of the linchpins in asymmetric synthesis. N-heterocyclic carbene (NHC)/copper cooperative catalysis has enabled highly efficient KR and DyKAT of racemic N-tosylaziridines by [3+3] annulation with isatin-derived enals, leading to highly enantioenriched N-tosylaziridine derivatives (up to >99 % ee) and a large library of spirooxindole derivatives with high structural diversity and stereoselectivity (up to >95:5 d.r., >99 % ee). Mechanistic studies suggest that the NHC can bind reversibly to the copper catalyst without compromising its catalytic activity and regulate the catalytic activity of the copper complex to switch the chemoselection between KR and DyKAT.
An Organocatalytic Kinetic Resolution of Aziridines by Thiol Nucleophiles
Sun, Song,Wang, Zhaobin,Li, Shijia,Zhou, Cong,Song, Lijuan,Huang, Hai,Sun, Jianwei
supporting information, p. 554 - 558 (2021/02/03)
We report the first organocatalytic kinetic resolution of unactivated aziridines by sulfur nucleophiles with excellent enantioselectivity. A suitable chiral phosphoric acid was found to catalyze the intermolecular ring opening under mild conditions, furni
