A Serendipitous Discovery: Nickel Catalyst for the Cycloaddition of Diynes with Unactivated Nitriles

Kumar, Puneet; Prescher, Simon; Louie, Janis

doi:10.1002/ange.201104475

Cited by 31 publications

(14 citation statements)

References 64 publications

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“…In 2005, we demonstrated that the SIPr ligand with Ni(COD) 2 did indeed catalyze the cycloaddition of diynes and nitriles (Scheme 12). 13a A variety of diynes were coupled with alkyl, aryl, and heteroaryl nitriles to afford fused pyridines in high yields ( 28 – 33 ).…”

Section: Ni-catalyzed Cycloaddition Of Alkynes and Nitrilesmentioning

confidence: 99%

“…We later extended this chemistry toward the use of cyanamides to form 2-aminopyridines. 13b We discovered that cyanamides were more reactive than simple nitriles and that a Ni(COD) 2 /IMes system is highly efficient in catalyzing the cycloaddition of internal diynes and cyanamides. Additionally, by change of the ligand from IMes to SIPr, terminal diynes were also incorporated in this cycloaddition (Scheme 14).…”

Section: Ni-catalyzed Cycloaddition Of Alkynes and Nitrilesmentioning

confidence: 99%

“…Surprisingly, our initial investigation using the catalytic Ni(COD) 2 /Xantphos system for the cycloaddition of diyne 39 and ketenimine 40 revealed the formation of pyridine 41 , albeit in low yield (Scheme 15). 13c…”

Section: Ni-catalyzed Cycloaddition Of Alkynes and Nitrilesmentioning

confidence: 99%

“…This result is contrary to our previous hypothesis that the highly electron-rich NHC ligand is required for the Ni-catalyzed cycloaddition of diynes and nitriles, since Xantphos is an electron-deficient bidentate phosphine ligand. 13c This Ni/Xantphos system offers a broad substrate scope in terms of both diynes and nitriles (Scheme 16).…”

Section: Ni-catalyzed Cycloaddition Of Alkynes and Nitrilesmentioning

confidence: 99%

“…Our initial investigations lead to the discovery of an interesting dimeric [Ni(IPr)RCN] 2 species (Scheme 17, 51a–e ) that can also catalyze the cycloaddition of diynes and nitriles (Scheme 17, 52 – 54 ). 13d…”

Section: Ni-catalyzed Cycloaddition Of Alkynes and Nitrilesmentioning

confidence: 99%

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Advances in Nickel-Catalyzed Cycloaddition Reactions To Construct Carbocycles and Heterocycles

2015

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Transition-metal catalysis has revolutionized the field of organic synthesis by facilitating the construction of complex organic molecules in a highly efficient manner. Although these catalysts are typically based on precious metals, researchers have made great strides in discovering new base metal catalysts over the past decade. This Account describes our efforts in this area and details the development of versatile Ni complexes that catalyze a variety of cycloaddition reactions to afford interesting carbocycles and heterocycles. First, we describe our early work in investigating the efficacy of N-heterocyclic carbene (NHC) ligands in Ni-catalyzed cycloaddition reactions with carbon dioxide and isocyanate. The use of sterically hindered, electron donating NHC ligands in these reactions significantly improved the substrate scope as well as reaction conditions in the syntheses of a variety of pyrones and pyridones. The high reactivity and versatility of these unique Ni(NHC) catalytic systems allowed us to develop unprecedented Ni-catalyzed cycloadditions that were unexplored due to the inefficacy of early Ni catalysts to promote hetero-oxidative coupling steps. We describe the development and mechanistic analysis of Ni/NHC catalysts that couple diynes and nitriles to form pyridines. Kinetic studies and stoichiometric reactions confirmed a hetero-oxidative coupling pathway associated with this Ni-catalyzed cycloaddition. We then describe a series of new substrates for Ni-catalyzed cycloaddition reactions such as vinylcyclopropanes, aldehydes, ketones, tropones, 3-azetidinones, and 3-oxetanones. In reactions with vinycyclopropanes and tropones, DFT calculations reveal noteworthy mechanistic steps such as a C-C σ-bond activation and an 8π-insertion of vinylcyclopropane and tropone, respectively. Similarly, the cycloaddition of 3-azetidinones and 3-oxetanones also requires Ni-catalyzed C-C σ-bond activation to form N- and O-containing heterocycles.

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Section: Ni-catalyzed Cycloaddition Of Alkynes and Nitrilesmentioning

confidence: 99%

Section: Ni-catalyzed Cycloaddition Of Alkynes and Nitrilesmentioning

confidence: 99%

Section: Ni-catalyzed Cycloaddition Of Alkynes and Nitrilesmentioning

confidence: 99%

Section: Ni-catalyzed Cycloaddition Of Alkynes and Nitrilesmentioning

confidence: 99%

Section: Ni-catalyzed Cycloaddition Of Alkynes and Nitrilesmentioning

confidence: 99%

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Advances in Nickel-Catalyzed Cycloaddition Reactions To Construct Carbocycles and Heterocycles

2015

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Iridium‐Catalyzed [2+2+2] Cycloaddition of α,ω‐Diynes with Cyanamides

et al. 2015

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Thec omplex[ Ir(cod)Cl] 2 /DPPF or rac-BINAP is an efficient catalyst for the [2+ +2+ +2] cycloaddition of a,w-diynesw ith cyanamides.Awide range of cyanamides derived from secondary amines are good coupling partners for a,w-diynes. Ther eaction of unsymmetrical a,w-diynes possessingt wo different internal alkyne moieties with cyanamides is regioselective.Ac ompetitive experiment showed that cyanamide is more reactive than nitrile. This higher reactivity of cyanamide than nitrile was analyzed based on density functional theory (DFT)c alculations at the B3LYP level.

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A Quick Access to 1‐(2‐Pyridyl)indoles via Solvent‐Free Ruthenium(II)‐Catalyzed Chemo‐ and Regioselective [2+2+2] Cycloaddition of α,ω‐Diynes and N‐Cyanoindoles

Chowdhury

Goswami

2017

Adv Synth Catal

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A new route to synthesize 1‐(2‐pyridyl)indole scaffolds via the solvent‐free, ruthenium(II)‐catalyzed, chemo‐ and regioselective [2+2+2] cycloaddition reaction of diynes with N‐cyanoindoles has been developed with good to excellent yields. Among the various transition metal‐based catalysts known for cycloaddition reaction to synthesize pyridine derivatives, chloro(pentamethylcyclopentadienyl)(cyclooctadiene)ruthenium(II) was established to be the best catalyst for this system. This efficient methodology provides 3‐substituted 1‐(2‐pyridyl)indole scaffolds having very close structural similarity with biological drug molecules.magnified image

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A Serendipitous Discovery: Nickel Catalyst for the Cycloaddition of Diynes with Unactivated Nitriles

Cited by 31 publications

References 64 publications

Advances in Nickel-Catalyzed Cycloaddition Reactions To Construct Carbocycles and Heterocycles

Advances in Nickel-Catalyzed Cycloaddition Reactions To Construct Carbocycles and Heterocycles

Iridium‐Catalyzed [2+2+2] Cycloaddition of α,ω‐Diynes with Cyanamides

A Quick Access to 1‐(2‐Pyridyl)indoles via Solvent‐Free Ruthenium(II)‐Catalyzed Chemo‐ and Regioselective [2+2+2] Cycloaddition of α,ω‐Diynes and N‐Cyanoindoles

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