A Formal [3+3+1] Reaction of Enyne‐Methylenecyclopropanes through Au(I)‐Catalyzed Enyne Cycloisomerization and Rh(I)‐Catalyzed [6+1] Reaction of Vinylspiropentanes and CO

Yu, Zhi‐Xiang; Li, Chen‐Long; Yang, Yusheng; Zhou, Yi

doi:10.1002/ajoc.202100571

Cited by 2 publications

(3 citation statements)

References 62 publications

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“…The relatively high barrier for C–H insertion of H (Δ G ‡ = 23.1 kcal mol –1 ) makes formation of spironorcaradiene I unlikely. Tricyclic spiro compounds like I have some literature precedent, but to our knowledge, spironorcaradienes of the sort we describe here have not been reported …”

Section: Resultsmentioning

confidence: 85%

“…Tricyclic spiro compounds like I have some literature precedent, but to our knowledge, spironorcaradienes of the sort we describe here have not been reported. 128 In summary, although C7 methyl substitution makes CP to form SBV more likely than in the C7 hydrogen-substituted case (Figure 1), methyl migration (Path I) could still preclude the desired chemoselectivity. We also computed the donor/ donor Rh-carbene system with a methyl group at C7 and predict that selectivity for heptafulvene formation is enhanced (a ΔΔG ‡ = 2.3 kcal mol −1 ; see the SI, Figure S4).…”

Section: ■ Computational Methodsmentioning

confidence: 99%

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Modulating Escape Channels of Cycloheptatrienyl Rhodium Carbenes To Form Semibullvalene

Laconsay

Tantillo

2023

J. Org. Chem.

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We describe the various escape channels available to dirhodium carbene intermediates from cycloheptatrienyl diazo compounds located with density functional theory. An intramolecular cyclopropanation would, in principle, provide a new route to semibullvalenes (SBVs). A detailed exploration of the potential energy surface reveals that methylating carbon-7 suppresses a competing β-hydride migration pathway to heptafulvene products, giving SBV formation a reasonable chance. During our explorations, we additionally discovered unusual spirononatriene, spironorcaradiene, and metal-stabilized 9-barbaralyl cation structures as local minima.

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Section: Resultsmentioning

confidence: 85%

Section: ■ Computational Methodsmentioning

confidence: 99%

Modulating Escape Channels of Cycloheptatrienyl Rhodium Carbenes To Form Semibullvalene

Laconsay

Tantillo

2023

J. Org. Chem.

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“…For example, until now only a limited number of transition metal-catalyzed cycloaddition reactions can be used to synthesize seven-membered carbocycles directly. 1,3 Therefore, chemists have been endeavoring to discover and develop new transition metal-catalyzed cycloadditions for this purpose.…”

Section: ■ Introductionmentioning

confidence: 99%

Why [4 + 2 + 1] but Not [2 + 2 + 1]? Why Allenes? A Mechanistic Study of the Rhodium-Catalyzed [4 + 2 + 1] Cycloaddition of In Situ Generated Ene–Ene–Allenes and Carbon Monoxide

Yang

Tian

et al. 2022

J. Org. Chem.

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Transition metal-catalyzed [4 + 2 + 1] cycloaddition of in situ generated ene/yne–ene–allenes (from ene/yne–ene propargyl esters) and carbon monoxide (CO) gives the [4 + 2 + 1] cycloadducts rather than [2 + 2 + 1] cycloadducts. Investigating the mechanism of this [4 + 2 + 1] reaction and understanding why the [2 + 2 + 1] reaction does not compete and the role of the allene moiety in the substrates are important. This is also helpful to guide the future design of new [4 + 2 + 1] cycloadditions. Reported here are the kinetic and computed studies of the [4 + 2 + 1] reactions of ene–ene propargyl esters and CO. A quantum chemical study (at the DLPNO-CCSD(T)//BMK level) revealed that the [4 + 2 + 1] reaction includes four key steps, which are 1,3-acyloxy migration (rate-determining step), oxidative cyclization, CO migratory insertion, and reductive elimination. The allene moiety in the substrates is critical for providing additional coordination to the rhodium center in the final step of the catalytic cycle, which in turn favors the reductive elimination transition state in the [4 + 2 + 1] rather than in the [2 + 2 + 1] pathway. The CO insertion step in the [4 + 2 + 1] reaction, which could occur through either the UP (favored here) or DOWN CO insertion pathway, has also been deeply scrutinized, and some guidance from this analysis has been provided to help the future design of new [4 + 2 + 1] reactions. Quantum chemical calculations have also been applied to explain why [4 + 2] and [4 + 1] cycloadditions do not happen and how trienes as side products for some substrates are generated.

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A Formal [3+3+1] Reaction of Enyne‐Methylenecyclopropanes through Au(I)‐Catalyzed Enyne Cycloisomerization and Rh(I)‐Catalyzed [6+1] Reaction of Vinylspiropentanes and CO

Cited by 2 publications

References 62 publications

Modulating Escape Channels of Cycloheptatrienyl Rhodium Carbenes To Form Semibullvalene

Modulating Escape Channels of Cycloheptatrienyl Rhodium Carbenes To Form Semibullvalene

Why [4 + 2 + 1] but Not [2 + 2 + 1]? Why Allenes? A Mechanistic Study of the Rhodium-Catalyzed [4 + 2 + 1] Cycloaddition of In Situ Generated Ene–Ene–Allenes and Carbon Monoxide

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