Unpredictable cycloisomerization of 1,11-dien-6-ynes by a common cobalt catalyst

Suleymanov, Abdusalom A.; Vasilyev, Dmitry; Novikov, Valentin V.; Nelyubina, Yulia V.; Perekalin, Dmitry S.

doi:10.3762/bjoc.13.62

Cited by 5 publications

(3 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Using a catalytic system consisting of CoBr 2 /phosphine ligand/Zn/ZnI 2 , various cycloisomerization products, including cyclohexene, diene, and cyclopropane, were readily obtained depending on the phosphine ligand structure (Scheme ). The authors proposed the following three different reaction pathways to rationalize the formation of different products. The reaction is initiated by oxidative cyclometalation of the enyne moiety, leading to metallacycle intermediate Co-443 .…”

Section: Cobalt-catalyzed Hydride Transfer Reactionsmentioning

confidence: 99%

“…Using a catalytic system consisting of CoBr 2 /phosphine ligand/Zn/ZnI 2 , various cycloisomerization products, including cyclohexene, diene, and cyclopropane, were readily obtained depending on the phosphine ligand structure (Scheme 160). 427 The authors proposed the following three different reaction pathways to rationalize the formation of different products. It was speculated that the steric factors of ligands determined the selectivity of this reaction; two large Ph 3 P ligands coordinated to the metal center hindered β-hydride elimination and promoted direct reductive elimination to yield condensed ring products 87.…”

Section: Olefin Isomerization Reactionsmentioning

confidence: 99%

See 1 more Smart Citation

Hydride Transfer Reactions Catalyzed by Cobalt Complexes

et al. 2018

View full text Add to dashboard Cite

Cobalt has become increasingly attractive in homogeneous catalysis because of its unique characteristics and outstanding catalytic performance in addition to being cheap and earth-abundant. Hydride transfer processes are involved in a broad range of organic transformations that allow the facile preparation of various useful chemicals and synthetic building blocks. These reactions have continuously received great attention both from academia and industry. In this perspective, we review homogeneous cobalt-catalyzed hydride transfer reactions according to the classified reaction types and provide a comprehensive overview of the design, synthesis, and reactivity of cobalt catalysts, their catalytic applications, and reaction mechanisms.

show abstract

Section: Cobalt-catalyzed Hydride Transfer Reactionsmentioning

confidence: 99%

“…Using a catalytic system consisting of CoBr 2 /phosphine ligand/Zn/ZnI 2 , various cycloisomerization products, including cyclohexene, diene, and cyclopropane, were readily obtained depending on the phosphine ligand structure (Scheme 160). 427 The authors proposed the following three different reaction pathways to rationalize the formation of different products. It was speculated that the steric factors of ligands determined the selectivity of this reaction; two large Ph 3 P ligands coordinated to the metal center hindered β-hydride elimination and promoted direct reductive elimination to yield condensed ring products 87.…”

Section: Olefin Isomerization Reactionsmentioning

confidence: 99%

Hydride Transfer Reactions Catalyzed by Cobalt Complexes

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Hence, as shown, 1,2-bis(diphenyl-phoshino)ethane led only to 15, whereas Ph 3 P created exclusively the [2+2+2] cycloadducts. 9 The latter were completely avoided in the cationic Rh-enabled cycloisomerization of seven imines of the type 16, giving only products of the type 17. 10 As the preceding summary illustrates, there is poor control over the outcome of the intramolecular transitionmetal-catalyzed stitching of two double bonds with a C≡C bond.…”

Section: Syn Thesismentioning

confidence: 99%

Stoichiometric and Catalytic (η 5-Cyclopentadienyl)cobalt-Mediated Cycloisomerizations of Ene-Yne-Ene Type Allyl Propargyl Ethers

Chang¹,

Gürtzgen²,

Johnson³

et al. 2019

Synthesis

View full text Add to dashboard Cite

The complexes CpCoL2 (Cp = C5H5; L = CO or CH2=CH2) mediate the cycloisomerizations of α,δ,ω-enynenes containing allylic ether linkages to 3-(oxacyclopentyl or cycloalkyl)furans via the intermediacy of isolable CpCo-η 4-dienes. A suggested mechanism comprises initial complexation of the triple bond and one of the double bonds, then oxidative coupling to a cobalt-2-cyclopentene, terminal double bond insertion to assemble a cobalta-4-cycloheptene, β-hydride elimination, and reductive elimination to furnish a CpCo-η 4-diene. When possible, the cascade continues through cobalt-mediated hydride shifts and dissociation of the aromatic furan ring. The outcome of a deuterium labeling experiment supports this hypothesis. The reaction exhibits variable stereoselectivity with a preference for the trans-product (or, when arrested, its syn-Me CpCo-η 4-diene precursor), but is completely regioselective in cases in which the two alkyne substituents are differentiated electronically by the presence or absence of an embedded oxygen. Regioselectivity is also attained by steric discrimination or blocking one of the two possible β-hydride elimination pathways. When furan formation is obviated by such regiocontrol, the sequence terminates in a stable CpCo-η 4-diene complex. The conversion of the cyclohexane-fused substrate methylidene-2-[5-(2-propenyloxy)-3-pentynyl]cyclohexane into mainly 1-[(1R*,3aS*,7aS*)-7a-methyloctahydroinden-1-yl]-1-ethanone demonstrates the potential utility of the method in complex synthesis.

show abstract