Intramolecular diels-alder reactions of dienamines with acrylates: trends in stereoselectivity upon substitution.

Wu, Tse-Chong; Houk, K. N.

doi:10.1016/s0040-4039(00)95078-0

Cited by 32 publications

(9 citation statements)

References 7 publications

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“…The presence of a terminal diene substituent (Y) has a negligible effect upon this preference (compare entries 6 vs. 8; 7 vs. 9). ( 2) In stark contrast to IMDA reactions of C1-substituted trienes, 11 the exo-endo selectivity is scarcely affected by the electronic demands of the C9-substituent (compare data for NH 2 vs. CN or CO 2 Me). ( 3) All TSs display substantial bond forming asynchronicity which is particularly pronounced for the C9-substituted systems.…”

mentioning

confidence: 99%

New insights into the endo–exo stereoselectivity of the intramolecular Diels-Alder reaction of 1,3,8-nonatrienes

et al. 2000

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mentioning

confidence: 99%

New insights into the endo–exo stereoselectivity of the intramolecular Diels-Alder reaction of 1,3,8-nonatrienes

et al. 2000

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“…This suggests that these bonds are still noncovalent rather than covalent. It is well-established that D–A reactions of unsymmetrical dienes and dienophiles usually go through a concerted asynchronous mechanism, in which the stretch and twist modes − are used to identify the asynchronicity. The stretch mode reveals the difference in the distances of the two C–C bonds that are formed in the transition state, and the twist mode, which is measured by a twist-asynchronicity parameter (θ), reflects the change of the diene and dienophile backbones from being parallel.…”

Section: Results and Discussionmentioning

confidence: 99%

Insights into the Diels–Alder Reaction between 3-Vinylindoles and Methyleneindolinone without and with the Assistance of Hydrogen-Bonding Catalyst Bisthiourea: Mechanism, Origin of Stereoselectivity, and Role of Catalyst

Bai

Yang

et al. 2017

J. Org. Chem.

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The Diels-Alder reaction between 3-vinylindoles and methyleneindolinone can proceed both under catalyst-free conditions and with bisthiourea as the catalyst. The reaction with bisthiourea is much faster and results in higher stereoselectivity of the product. The reaction mechanism, origin of stereoselectivity, and role of the catalyst were elaborated based on quantum mechanical calculations and theoretical methods of reactivity indices, NCI, QTAIM, and distortion/interaction models. In the uncatalyzed reaction, the two C-C bonds that are formed undergo conversion from noncovalent to covalent bonding via a concerted asynchronous mechanism. The weak intermolecular interactions formed in the transition state play important roles. The difference between the interaction and distortion energies is responsible for the stereoselectivity. In the catalyzed reaction, bisthiourea induces both the diene and dienophile to approach it via weak intermolecular interactions, which greatly lowers the energy barrier of the reaction and leads to the product with excellent stereoselectivity. The possible pathways of this reaction were explored, which suggested that the formation of the two C-C bonds goes through either a stepwise or concerted asynchronous mechanism. These results detail the reaction mechanism and shed light on both the significant role of the bisthiourea catalyst and the origin of stereoselectivity for this type of Diels-Alder reaction and related ones.

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“…Intramolecular Diels−Alder cycloadditions have been studied extensively, − and stereoselection of cis- or trans-fused products depends on both electronic and steric effects. Scheme shows the two transition states C and D for cis- and trans-fused stereoselections for decatriene according to the Houk's concept of “twist asynchronicity” . In this concept, stereoselection is controlled by the timing of bond formation in the transition state.…”

Section: Resultsmentioning

confidence: 99%

Facile Synthesis of Oxa- and Azacyclic Dienes via Cycloalkenation of Alkynyltungsten Compounds. Stereoselective Construction of Tricyclic Furan and Pyran Derivatives via Intramolecular Diels−Alder Reaction

Pan

et al. 2000

J. Org. Chem.

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A convenient and short synthesis of functionalized oxacyclic and azacyclic dienes is developed on the basis of organotungsten chemistry. Alkynyltungsten compounds bearing a tethered alcohol and amine are treated with aldehydes and BF(3).Et(2)O in cold diethyl ether to give tungsten-heterocyclic carbenium salts, further leading to tungsten-heterocyclic dienes via deprotonation with Et(3)N. Hydrodemetalation of these tungsten-heterocyclic dienes is performed by the action of anhydrous Me(3)NO in CH(3)CN. This method is applicable to the synthesis of a number of oxa- and azacyclic dienes, including those tethered with an electron-deficient olefin. The oxacyclic 1,3,8-nonatrienes and 1,3,9-decatrienes undergo intramolecular Diels-Alder reactions upon heating in toluene, yielding tricyclic tetrahydropyran and -furan derivatives with excellent diastereoselectivities.

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Intramolecular diels-alder reactions of dienamines with acrylates: trends in stereoselectivity upon substitution.

Cited by 32 publications

References 7 publications

New insights into the endo–exo stereoselectivity of the intramolecular Diels-Alder reaction of 1,3,8-nonatrienes

New insights into the endo–exo stereoselectivity of the intramolecular Diels-Alder reaction of 1,3,8-nonatrienes

Insights into the Diels–Alder Reaction between 3-Vinylindoles and Methyleneindolinone without and with the Assistance of Hydrogen-Bonding Catalyst Bisthiourea: Mechanism, Origin of Stereoselectivity, and Role of Catalyst

Facile Synthesis of Oxa- and Azacyclic Dienes via Cycloalkenation of Alkynyltungsten Compounds. Stereoselective Construction of Tricyclic Furan and Pyran Derivatives via Intramolecular Diels−Alder Reaction

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