Distortion, Tether, and Entropy Effects on Transannular Diels–Alder Cycloaddition Reactions of 10–18-Membered Rings

He, Cyndi Qixin; Chen, Tiffany Q.; Patel, Ashay; Karabıyıkoğlu, Sedef; Merlic, Craig A.; Houk, K. N.

doi:10.1021/acs.joc.5b02288

Cited by 9 publications

(7 citation statements)

References 41 publications

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“…The very low barrier to cyclization of the protonated Os(VI) species 15 H + (Δ G ‡ = 2.1 kcal/mol) may be attributed to favorable orbital overlap arising from the tetrahedral TS geometry, while Os(VIII) TS 16 [ ox ] H + may suffer from increased distortion and steric interactions. This proposal is supported through distortion/interaction analysis of the SRS TSs (see the Supporting Information for details). , …”

Section: Results and Discussionsupporting

confidence: 77%

Mechanism of Os-Catalyzed Oxidative Cyclization of 1,5-Dienes

et al. 2019

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The oxidative cyclization of 1,5-dienes by metal oxo species is a powerful method for stereocontrolled synthesis of tetrahydrofuran diols (THF-diols), structural motifs present in many bioactive natural products. Oxidative cyclization of (2E,6E)-octa-2,6-diene catalyzed by OsO4/NMO as has been studied using density functional theory (DFT) calculations (M06-2X/augcc-pVDZ/Hay-Wadt VDZ (n+1) ECP), highlighting the remarkable effect of acid on the fate of the first intermediate, an Os(VI) dioxoglycolate. Strong acid promotes cyclization of the Os(VI) dioxoglycolate, or its NMO complex, through protonation of an oxo ligand to give more electrophilic species. By contrast, in absence of acid reoxidation may occur to afford the Os(VIII) trioxoglycolate, which is shown to favor conventional "second cycle" dihydroxylation reactivity rather than cyclization. The results of the calculations are consistent with experimental results for reactions of OsO4/NMO with 1,5-dienes with acid (oxidative cyclization) and without acid (second cycle osmylation / dihydroxylation). Detailed evaluation of potential catalytic cycles support oxidation of the cyclized Os(IV) THF diolate intermediate to the corresponding Os(VI) species followed by slow hydrolysis, and finally regeneration of OsO4.

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Section: Results and Discussionsupporting

confidence: 77%

Mechanism of Os-Catalyzed Oxidative Cyclization of 1,5-Dienes

et al. 2019

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“…However, some reaction types that are important in organic chemistry, such as pericyclic, hydride-transfer, and halogen-atom transfer reactions, are relatively rare in biological contexts or are not sufficiently represented in the M-CSA. For these reaction types, we explored the literature and compiled a number of reactions from various published mechanistic studies to complete our database. − …”

Section: Design Of Bh9 and Computational Detailsmentioning

confidence: 99%

BH9, a New Comprehensive Benchmark Data Set for Barrier Heights and Reaction Energies: Assessment of Density Functional Approximations and Basis Set Incompleteness Potentials

Prasad

Pei

Edelmann

et al. 2021

J. Chem. Theory Comput.

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The calculation of accurate reaction energies and barrier heights is essential in computational studies of reaction mechanisms and thermochemistry. To assess methods regarding their ability to predict these two properties, high-quality benchmark sets are required that comprise a reasonably large and diverse set of organic reactions. Due to the time-consuming nature of both locating transition states and computing accurate reference energies for reactions involving large molecules, previous benchmark sets have been limited in scope, the number of reactions considered, and the size of the reactant and product molecules. Recent advances in coupled-cluster theory, in particular local correlation methods like DLPNO-CCSD(T), now allow the calculation of reaction energies and barrier heights for relatively large systems. In this work, we present a comprehensive and diverse benchmark set of barrier heights and reaction energies based on DLPNO-CCSD(T)/CBS called BH9. BH9 comprises 449 chemical reactions belonging to nine types common in organic chemistry and biochemistry. We examine the accuracy of DLPNO-CCSD(T) vis-a-vis canonical CCSD(T) for a subset of BH9 and conclude that, although there is a penalty in using the DLPNO approximation, the reference data are accurate enough to serve as a benchmark for density functional theory (DFT) methods. We then present two applications of the BH9 set. First, we examine the performance of several density functional approximations commonly used in thermochemical and mechanistic studies. Second, we assess our basis set incompleteness potentials regarding their ability to mitigate basis set incompleteness errors. The number of data points, the diversity of the reactions considered, and the relatively large size of the reactant molecules make BH9 the most comprehensive thermochemical benchmark set to date and a useful tool for the development and assessment of computational methods.

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“…We previously reported the serendipitous discovery that dienyne complexes 1 and 5 undergo smooth cobalt-promoted transannular Diels–Alder (TADA) reactions (eqs and 3) under mild reaction conditions, rather than the TAPK reaction . This mode of reactivity is due to low transition state distortion energies imparted on the diene and dienophile by their linking tethers and the strain release of those tethers in the transition state . Choice of promoter to activate loss of a carbonyl group was critical for success of the reaction, as is known for many reactions with dicobalt hexacarbonyl alkyne complexes .…”

Section: Resultsmentioning

confidence: 99%

Cycloaddition Reactions of Cobalt-Complexed Macrocyclic Alkynes: The Transannular Pauson–Khand Reaction

2017

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The Pauson-Khand reaction is a powerful tool for the synthesis of cyclopentenones through the efficient [2 + 2 + 1] cycloaddition of dicobalt alkyne complexes with alkenes. While intermolecular and intramolecular variants are widely known, transannular versions of this reaction are unknown and the basis of this study. Macrocyclic enyne and dienyne complexes were readily synthesized by palladium(II)-catalyzed oxidative macrocyclizations of bis(vinyl boronate esters) or ring-closing metathesis reactions followed by complexation with dicobalt octacarbonyl. Several reaction modalities of these macrocyclic complexes were uncovered. In addition to the first successful transannular Pauson-Khand reactions, other intermolecular and transannular cycloaddition reactions included intermolecular Pauson-Khand reactions, transannular [4 + 2] cycloaddition reactions, intermolecular [2 + 2 + 2] cycloaddition reactions, and intermolecular [2 + 2 + 1 + 1] cycloaddition reactions. The structural and reaction requirements for each process are presented.

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Distortion, Tether, and Entropy Effects on Transannular Diels–Alder Cycloaddition Reactions of 10–18-Membered Rings

Cited by 9 publications

References 41 publications

Mechanism of Os-Catalyzed Oxidative Cyclization of 1,5-Dienes

Mechanism of Os-Catalyzed Oxidative Cyclization of 1,5-Dienes

BH9, a New Comprehensive Benchmark Data Set for Barrier Heights and Reaction Energies: Assessment of Density Functional Approximations and Basis Set Incompleteness Potentials

Cycloaddition Reactions of Cobalt-Complexed Macrocyclic Alkynes: The Transannular Pauson–Khand Reaction

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