Polynuclear Phosphoramidite Copper Complexes with Mixed Trigonal/Tetrahedral Coordination in THF

Rekowski, Felicitas von; Gschwind, Ruth M.

doi:10.1021/om500751q

Cited by 3 publications

(3 citation statements)

References 17 publications

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“…Primary organocopper(I) species are dynamic and reactive entities with a tendency to aggregate, resulting in complex mixtures of species . Here aggregation and reactivity are strongly linked to reaction outcome (yield, chemo- and enantioselectivity) and are highly dependent on solvent interactions, counterion and ligand effects, and more tractable variables such as concentration and temperature. ,,,− Gschwind’s elegant work shed light on the nature of precatalytic Cu-complexes in solution using NMR spectroscopy. ,− …”

Section: Introductionmentioning

confidence: 99%

Mechanistic Studies on a Cu-Catalyzed Asymmetric Allylic Alkylation with Cyclic Racemic Starting Materials

et al. 2017

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Mechanistic studies on Cu-catalyzed asymmetric additions of alkylzirconocene nucleophiles to racemic allylic halide electrophiles were conducted using a combination of isotopic labeling, NMR spectroscopy, kinetic modeling, structure-activity relationships, and new reaction development. Kinetic and dynamic NMR spectroscopic studies provided insight into the oligomeric Cu-ligand complexes, which evolve during the course of the reaction to become faster and more highly enantioselective. The Cu-counterions play a role in both selecting different pathways and in racemizing the starting material via formation of an allyl iodide intermediate. We quantify the rate of Cu-catalyzed allyl iodide isomerization and identify a series of conditions under which the formation and racemization of the allyl iodide occurs. We developed reaction conditions where racemic allylic phosphates are suitable substrates using new phosphoramidite ligand D. D also allows highly enantioselective addition to racemic seven-membered-ring allyl chlorides for the first time. H andH NMR spectroscopy experiments on reactions using allylic phosphates showed the importance of allyl chloride intermediates, which form either by the action of TMSCl or from an adventitious chloride source. Overall these studies support a mechanism where complex oligomeric catalysts both racemize the starting material and select one enantiomer for a highly enantioselective reaction. It is anticipated that this work will enable extension of copper-catalyzed asymmetric reactions and provide understanding on how to develop dynamic kinetic asymmetric transformations more broadly.

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Section: Introductionmentioning

confidence: 99%

Mechanistic Studies on a Cu-Catalyzed Asymmetric Allylic Alkylation with Cyclic Racemic Starting Materials

et al. 2017

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“…The absolute configurations of compounds 3 were assigned to be S by analogy to 3g and 3r. Given that it is sometimes unpredictable to infer the identities of coppers peciesi ns olution from crystal structures, the solution dynamics of complex 13 was investigated using temperature-dependent 31 PNMR spectroscopy, [36] with an aim to probe into the structural integrity of the precatalyst in solution. Althoughc hiral cuprous diphosphine complexes have found broad applications in asymmetric catalysis, the structural information on the active species remains less explored, and only a few studies on the catalysis relevant structures in solution have been reported.…”

Section: Mechanistic Studiesmentioning

confidence: 99%

Synthesis of Chiral Tertiary α,α‐Difluoromethyl Carbinols by Cu‐Catalyzed Asymmetric Propargylation

Guo

Zhang

Wang

et al. 2019

Chemistry A European J

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Chiral a,a-difluoromethyl carbinolsa re recurring structural motifs in many therapeutic agents. Despite the indubitable interesti nt he catalytic asymmetric synthesis of such compounds,t his research field still remains largely underexplored. Herein, an efficient approacht oarange of chiral homopropargylic a,a-difluoromethyl carbinols has been developed, through aC u-catalyzed enantioselective propargylation of a,a-difluoroketones with (pinacolato)allenylboron. In the presence of ac uprous complex, generated in situ from CuCl and as piroketal-based diphosphine( SKP) ligand, av ariety of aryl-, heteroaryl-, alkyl-, alkynyl,a lkenyl, or benzyloxycarbonyl-substituted a,a-difluoromethyl carbinols were obtained in 75-99 %y ields with 84-98 % ee values. The catalytic system was further investigated using a combined dynamic NMR spectroscopic,X -ray crystallographic, and non-linear effect studies. The origin of the enantioselectivity was rationalized based on DFT calculations.F inally, several efficient transformations were showcased to highlight the utilities of the protocol in synthesis of complex compounds bearing an a,a-difluoromethyl carbinol moiety.[a] Dr.Supporting information and the ORCID identification number(s) for the author(s) of this articlecan be found under: https://doi.

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“…In the past decades, copper(I) complexes with nitrogen, phosphorus, and sulfur organic ligands have been extensively investigated because of their interesting structures and photochemical, photophysical properties. − Copper(I) iodide complexes, in particular, demonstrate rich photophysical behavior which could be manipulated by a wide variety of cluster chromophores [Cu n I n ] − and the supporting organic ligands. With regard to N-heterocyclic organic ligands, poly(pyridyl), − ,− ,,, poly(triazolyl), − poly(imidazolyl), − pyrazine, − poly(pyrazolyl), − and poly(benzimidazolyl) , have been extensively employed in the assembly of the [Cu n I...…”

Section: Introductionmentioning

confidence: 99%

Ligand Coordination Site-Directed Assembly of Copper(I) Iodide Complexes of ((Pyridyl)-1-pyrazolyl)pyridine

et al. 2016

Crystal Growth & Design

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A series of ((pyridinyl)-1H-pyrazolyl)pyridine (pypzpy) ligands in which the pyrazolyl ring at 1- and 3-positions is modified by two 2-, 3-, or 4-pyridyl groups were prepared. Reaction of CuI with 2-(1-(pyridin-2-yl)-1H-pyrazolyl)pyridine (2,2′-pypzpy) in MeCN at room temperature or solvothermal reaction of the same components at 120 °C afforded one binuclear complex [{(2,2′-pypzpy)Cu}(μ-I)]2 (1). Treatment of CuI with 3-(1-(pyridin-2-yl)-1H-pyrazolyl)pyridine (3,2′-pypzpy) at room temperature or at 120 °C produced one-dimensional (1D) polymer [{Cu3(μ3-I)3}(μ-3,2′-pypzpy)] n (2) and one two-dimensional (2D) polymer [{Cu2(μ-I)(μ3-I)}2(3,2′-pypzpy)2] n (3), respectively. Similar reactions of CuI with 4-(1-(pyridin-2-yl)-1H-pyrazolyl)pyridine (4,2′-pypzpy) at room temperature or at 150 °C yielded one 1D polymeric complex [{Cu(μ3-I)}2(4,2′-pypzpy)2{Cu(μ-I)}2] n (4). Complexes [{Cu3(μ3-I)3}(μ-2,3′-pypzpy)] n (5), [(CuI)(μ-2,3′-pypzpy)]2 (6), [(Cu2I2)(3,3′-pypzpy)] (7), [(CuI)(4,3′-pypzpy)] (8), [{Cu(μ3-I)}2(μ-2,4′-pypzpy)2{Cu(μ-I)}2] n (9), [(CuI)(3,4′-pypzpy)] (10), and [(CuI)(μ-4,4′-pypzpy)] n (11) could be isolated by solution reactions or solvothermal reactions of CuI with 2-, 3-, 4-(1-(pyridin-3-yl)-1H-pyrazolyl)pyridine (2,3′-, 3,3′-, 4,3′-pypzpy), or 2-, 3-, 4-(1-(pyridin-4-yl)-1H-pyrazolyl)pyridine (2,4′-, 3,4′-, 4,4′-pypzpy). Compounds 1–11 were characterized by IR, elemental analysis, powder X-ray diffraction, and single-crystal X-ray crystallography. Complex 1 contains a normal [Cu(μ-I)]2 dimeric structure. Complexes 2 and 5 consist of a unique displaced staircase chain [Cu2(μ3-I)2] n . Complex 3 has a 2D network formed by linking chairlike [Cu2(μ-I)(μ3-I)]2 units with two pairs of 3,2′-pypzpy bridges. Complexes 4 and 9 have a rare 1D triple chain, in which one internal 1D ladder-like chain [Cu2(μ3-I)2] n is connected with two zigzag chains [Cu(μ-I)] n via 4,2′-pypzpy or 2,4′-pypzpy ligands. Compound 6 consists of two [CuI] units interconnected by two 2,3′-pypzpy ligands. Compound 11 contains a 1D chain assembled by monomeric [CuI] units and 4,4′-pypzpy ligands. The luminescence properties of 1–11 in solid state were also investigated at room temperature. These results offer an interesting insight into how the coordination sites of the pypzpy ligands do exert great impact on their coordination modes, the coordination spheres of the Cu(I) centers, the formation of the [Cu n I n ] motifs and the topological structures of the final complexes.

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Polynuclear Phosphoramidite Copper Complexes with Mixed Trigonal/Tetrahedral Coordination in THF

Abstract: Scheme 1. Proposed Precatalytic Structures of (a) Diphosphine Copper Complexes 11 and (b) Phosphoramidite Copper Complexes 13 Note pubs.acs.org/Organometallics

Cited by 3 publications

References 17 publications

Mechanistic Studies on a Cu-Catalyzed Asymmetric Allylic Alkylation with Cyclic Racemic Starting Materials

Mechanistic Studies on a Cu-Catalyzed Asymmetric Allylic Alkylation with Cyclic Racemic Starting Materials

Synthesis of Chiral Tertiary α,α‐Difluoromethyl Carbinols by Cu‐Catalyzed Asymmetric Propargylation

Ligand Coordination Site-Directed Assembly of Copper(I) Iodide Complexes of ((Pyridyl)-1-pyrazolyl)pyridine

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