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.
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.
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).
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.
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.
Iron(ii)-catalyzed intermolecular aziridination of alkenes employing hydroxylamine derivatives as clean nitrene sources
Berhal, Farouk,Grimaud, Laurence,Kirby, Georgina,Prestat, Guillaume,Vitale, Maxime R.
supporting information, p. 9428 - 9432 (2021/12/09)
The iron-catalyzed intermolecular aziridination of alkenes with hydroxylamine derivatives is described. Using simple iron(ii) sources and readily available ligands, the formal (2 + 1) cycloaddition process proved to be efficient on both styrenes and aliphatic alkenes, providing access to a wide range of aziridines. In these particularly sustainable reaction conditions, yields up to 89% could be obtained, with a catalyst loading which could be lowered to 5 mol% when the reaction was performed on large scale. Preliminary mechanistic studies suggest that both concerted and stepwise pathways are operating in this transformation. This journal is
A Dicopper Nitrenoid by Oxidation of a CuICuICore: Synthesis, Electronic Structure, and Reactivity
Desnoyer, Addison N.,Nicolay, Amélie,Ziegler, Micah S.,Lakshmi,Cundari, Thomas R.,Tilley, T. Don
supporting information, p. 7135 - 7143 (2021/05/31)
A dicopper nitrenoid complex was prepared by formal oxidative addition of the nitrenoid fragment to a dicopper(I) center by reaction with the iminoiodinane PhINTs (Ts = tosylate). This nitrenoid complex, (DPFN)Cu2(μ-NTs)[NTf2]2 (DPFN = 2,7-bis(fluorodi(2-pyridyl)methyl)-1,8-naphthyridine), is a powerful H atom abstractor that reacts with a range of strong C-H bonds to form a mixed-valence Cu(I)/Cu(II) μ-NHTs amido complex in the first example of a clean H atom transfer to a dicopper nitrenoid core. In line with this reactivity, DFT calculations reveal that the nitrenoid is best described as an iminyl (NR radical anion) complex. The nitrenoid was trapped by the addition of water to form a mixed-donor hydroxo/amido dicopper(II) complex, which was independently obtained by reaction of a Cu2(μ-OH)2 complex with an amine through a protonolysis pathway. This mixed-donor complex is an analogue for the proposed intermediate in copper-catalyzed Chan-Evans-Lam coupling, which proceeds via C-X (X = N or O) bond formation. Treatment of the dicopper(II) mixed donor complex with MgPh2(THF)2 resulted in generation of a mixture that includes both phenol and a previously reported dicopper(I) bridging phenyl complex, illustrating that both reduction of dicopper(II) to dicopper(I) and concomitant C-X bond formation are feasible.
