Visible-light-activated copper(<scp>i</scp>) catalyzed oxidative C<sub>sp</sub>–C<sub>sp</sub> cross-coupling reaction: efficient synthesis of unsymmetrical conjugated diynes without ligands and base

Photoredox chemistry with metal complexes as sensitizers and catalysts frequently relies on precious elements such as ruthenium or iridium. Over the past 5 years, important progress towards the use of complexes made from earth-abundant elements in photoredox catalysis has been made. This review summarizes the advances made with photoactive Cr , Fe , Cu , Zn , Zr , Mo , and U complexes in the context of synthetic organic photoredox chemistry using visible light as an energy input. Mechanistic considerations are combined with discussions of reaction types and scopes. Perspectives for the future of the field are discussed against the background of recent significant developments of new photoactive metal complexes made from earth-abundant elements.

show abstract

“…c) Presumed mechanism. [60] Chem.E ur.J. 2018, 24,2039 -2058 www.chemeurj.org Review N-substituted anilinesa re not tolerated.…”

Section: Reviewmentioning

confidence: 99%

Photoredox Catalysis with Metal Complexes Made from Earth‐Abundant Elements

Larsen

Wenger

2017

Chemistry A European J

318

253

View full text Add to dashboard Cite

show abstract

“…13 Compared to the well-established protocols for the synthesis of diynes via classical Glaser-Hay and/or Cadiot-Chodkiewicz coupling, Hwang’s approach obviates the need for high reaction temperature, pre-functionalized substrates, and employment of excess base, ligands, and costly oxidants. More importantly, Hwang’s photoinduced approach allows for efficient coupling of electron deficient alkynes ( 27c-d ), which overcomes the inherent limitations of the aforementioned protocols.…”

Section: Visible Light-induced Cu-catalyzed Reactionsmentioning

confidence: 99%

Visible light-induced transition metal-catalyzed transformations: beyond conventional photosensitizers

2017

View full text Add to dashboard Cite

Employment of simple transition metal (TM= Co, Fe, Cu, Pd, Pt, Au)-based photocatalyst (PC) led to the dramatic acceleration of known TM-catalyzed reactions, as well as to the discovery of unprecedented chemical transformations. Compared to the conventional cooperative/dual photocatalysis (type B, Figure 1), this new class of unconventional PCs operates via a single photoexcitation/catalytic cycle, where the TM complex plays a “double duty” role by harvesting light and catalyzing the chemical transformation. Also, these TM photocatalysts participate in the bond-forming/breaking event in the transformation via a substrate-TM interaction, an aspect that is uncommon for conventional photocatalysis (type A, Figure 1). This tutorial review highlights the recent advances in this emerging area.

show abstract

“…Recently, several protocols were established that display larger heteroselectivity and provide sufficient yields of the unsymmetrical diyne with application of the major alkyne in only two‐fold or even lower excess . Heterogeneous and homogeneous copper and gold catalysts as well as bimetallic Pd/Cu‐ and Ni/Ag‐based systems were successfully employed for these transformations. Propargylic and homopropargylic alcohols, ethers and esters are particularly useful substrates for these heterocouplings, since selective and subsequent alkyne activation is mediated by oxygen‐metal interaction …”

Section: Introductionmentioning

confidence: 99%

Unraveling the Mechanism of 1,3‐Diyne Cross‐Metathesis Catalyzed by Silanolate‐Supported Tungsten Alkylidyne Complexes

Schnabel

Melcher

Brandhorst

et al. 2018

Chemistry A European J

View full text Add to dashboard Cite

The benzylidyne complex [PhC≡W{OSi(OtBu) } ] (1) catalyzed the cross-metathesis between 1,4-bis(trimethylsilyl)-1,3-butadiyne (2) and symmetrical 1,3-diynes (3) efficiently, which gave access to TMS-capped 1,3-diynes RC≡C-C≡CSiMe (4). Diyne cross-metathesis (DYCM) studies with C-labeled diyne PhC≡ C- C≡CPh (3*) revealed that this reaction proceeds through reversible carbon-carbon triple-bond cleavage and formation according to the conventional mechanism of alkyne metathesis. The reaction between 1 and 3* afforded the 3-phenylpropynylidyne complex PhC≡ C- C≡W{OSi(OtBu) } ] (5*), indicating that alkynylalkylidyne complexes are likely to act as catalytically active species. Attempts to isolate 5* from mixtures of 1 and 3* afforded crystals of the ditungsten 2-butyne-1,4-diylidyne complex [(tBuO) SiO} W≡ C- C≡ C- C≡W{OSi(OtBu) } ] (6*), which was additionally characterized by X-ray diffraction analysis. Depolymerization-macrocyclization of a carbazole-butadiyne polymer, obtained from 3,6-diethynyl-9-dodecylcarbazole (7) under copper-catalyzed Hay coupling conditions, was also efficiently catalyzed by 1 and afforded a mixture of mono-, diyne- and triyne-containing tetrameric macrocycles, revealing that diyne disproportionation into monoynes and triynes occurs as a slow side reaction that interferes with a high diyne metathesis selectivity. Potential catalytic pathways were studied by means of quantum-chemical calculations, and kinetic studies were performed to substantiate an α,α-mechanism for the catalytic diyne metathesis reaction, which involves intermediate alkynylalkylidyne and α,α'-dialkynylmetallacyclobutadiene intermediates.

show abstract

Visible-light-activated copper(i) catalyzed oxidative C_sp–C_sp cross-coupling reaction: efficient synthesis of unsymmetrical conjugated diynes without ligands and base

Abstract: An efficient and eco-friendly approach to Csp–Csp cross-coupling of terminal alkynes for the construction of unsymmetrical conjugated diynes via a visible-light-induced CuCl catalysed process at room temperature is described.

Cited by 91 publications

References 35 publications

Photoredox Catalysis with Metal Complexes Made from Earth‐Abundant Elements

Photoredox Catalysis with Metal Complexes Made from Earth‐Abundant Elements

Visible light-induced transition metal-catalyzed transformations: beyond conventional photosensitizers

Unraveling the Mechanism of 1,3‐Diyne Cross‐Metathesis Catalyzed by Silanolate‐Supported Tungsten Alkylidyne Complexes

Contact Info

Product

Resources

About

Visible-light-activated copper(i) catalyzed oxidative Csp–Csp cross-coupling reaction: efficient synthesis of unsymmetrical conjugated diynes without ligands and base

Abstract: An efficient and eco-friendly approach to Csp–Csp cross-coupling of terminal alkynes for the construction of unsymmetrical conjugated diynes via a visible-light-induced CuCl catalysed process at room temperature is described.

Cited by 91 publications

References 35 publications

Photoredox Catalysis with Metal Complexes Made from Earth‐Abundant Elements

Photoredox Catalysis with Metal Complexes Made from Earth‐Abundant Elements

Visible light-induced transition metal-catalyzed transformations: beyond conventional photosensitizers

Unraveling the Mechanism of 1,3‐Diyne Cross‐Metathesis Catalyzed by Silanolate‐Supported Tungsten Alkylidyne Complexes

Contact Info

Product

Resources

About

Visible-light-activated copper(i) catalyzed oxidative C_sp–C_sp cross-coupling reaction: efficient synthesis of unsymmetrical conjugated diynes without ligands and base