Alkane C–H Insertion by Aryne Intermediates with a Silver Catalyst

Yun, Sang Young; Wang, Kung Pern; Lee, Nam Kyu; Mamidipalli, Phani; Lee, Daesung

doi:10.1021/ja400477r

Cited by 146 publications

(57 citation statements)

References 71 publications

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“…The overall process has been shown to be quite general, 4 and serves as a platform for the discovery of new reaction processes. 5,6 Coupled cluster calculations including single, double, and perturbatively estimated triple excitations (CCSD(T)) indicate that o -benzyne is approximately 50 kcal/mol more stable than 1,3-butadiyne and ethyne. 7 Similar exergonicities have been computed for the free energy changes that attend intramolecular HDDA processes.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of the Intramolecular Hexadehydro-Diels–Alder Reaction

et al. 2015

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Theoretical analysis of the mechanism of the intramolecular hexadehydro-Diels–Alder (HDDA) reaction, validated against prior and newly measured kinetic data for a number of different tethered yne-diynes, indicates that the reaction proceeds in a highly asynchronous fashion. The rate-determining step is bond formation at the alkyne termini nearest the tether, which involves a transition-state structure exhibiting substantial diradical character. Whether the reaction then continues to close the remaining bond in a concerted fashion or in a stepwise fashion (i.e., with an intervening intermediate) depends on the substituents at the remaining terminal alkyne positions. Computational modeling of the HDDA reaction is complicated by the significant diradical character that arises along the reaction coordinate, which leads to instabilities in both restricted singlet Kohn-Sham density functional theory (DFT) and coupled-cluster theory based on a Hartree-Fock reference wave function. A consistent picture emerges, however, from comparison of broken-symmetry DFT calculations and second-order perturbation theory based on complete-active-space self-consistent-field (CASPT2) calculations.

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Section: Introductionmentioning

confidence: 99%

Mechanism of the Intramolecular Hexadehydro-Diels–Alder Reaction

et al. 2015

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“…1,8 The products 9a-g are formed via the HDDA cascade comprising initial, rate-limiting cycloisomerization of 7 to benzynes 8 followed by rapid trapping by the pendant silyl ether. In every instance, product 9 was, by far, the major product formed and, most often, the only product observed.…”

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confidence: 99%

The Hexadehydro-Diels–Alder Cycloisomerization Reaction Proceeds by a Stepwise Mechanism

2016

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We report here experiments showing that the hexadehydro-Diels–Alder (HDDA) cycloisomerization reaction proceeds in a stepwise manner—i.e., via a diradical intermediate. Judicious use of substituent effects was decisive. We prepared: (i) a series of triyne HDDA substrates that differed only in the group, R, present on the remote terminus of the diynophilic alkyne and (ii) an analogous series of dienophilic alkynes (n-C8H16COC≡CR) for use in classical Diels-Alder (DA) reactions (with 1,3-cyclopentadiene). The R groups were: CF3, CHO, COMe/Et, CO2Me, CONMe2/Et2, H, and 1-propynyl. The relative rates of both the HDDA cyclization reactions and the simple DA cycloadditions were measured. The reactivity trends revealed a dramatic difference in the behaviors of the CF3 (slowest HDDA and nearly fastest DA) vs. 1-propynyl (fastest HDDA and slowest DA) containing members of each series. These differences can be explained by invoking radical-stabilizing energies rather than electron-withdrawing effects as the dominating feature of the HDDA reaction.

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“…In 2013, Lee and coworkers reported silver-mediated intramolecular carbene insertion to sp 3 C-H from alkyne building blocks, mediated by aryne intermediates [26]. In this reaction, using silver trifluoromethanesulfonate (AgOTf, 10 mol%) or AgSbF 6 (10 mol%) as the catalyst and toluene as the solvent at 90 C for 5 h, good to excellent yields were obtained for various unsymmetrical and symmetrical bis-1,3-diyne substrates.…”

Section: Direct C-c Bond Formationmentioning

confidence: 99%

Silver-Mediated Direct sp3 C–H Bond Functionalization

Zhou

Shi

2015

Topics in Organometallic Chemistry

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Direct sp 3 C-H bond functionalization is an efficient, straightforward, and powerful method to construct new C-X (X¼C, N, F, S) bonds from nonfunctionalized aliphatic motif of organic molecules, which has been used in late-stage modification of complex molecules. In this chapter, the recent developments of silver-mediated direct sp 3 C-H functionalizations are reviewed, categorized by C-C bond formation (C-H insertion), C-N bond formation (intramolecular and intermolecular amination/amidation), C-F bond formation, and C-S bond formation.

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Alkane C–H Insertion by Aryne Intermediates with a Silver Catalyst

Cited by 146 publications

References 71 publications

Mechanism of the Intramolecular Hexadehydro-Diels–Alder Reaction

Mechanism of the Intramolecular Hexadehydro-Diels–Alder Reaction

The Hexadehydro-Diels–Alder Cycloisomerization Reaction Proceeds by a Stepwise Mechanism

Silver-Mediated Direct sp3 C–H Bond Functionalization

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