Governing organic reactions through secondary orbital interactions. Semiempirical and density functional theory study of catalyzed cycloaddition reactions between pyrrole and ether dienophiles

Jursic, Branko S.

doi:10.1039/a803738h

Cited by 6 publications

(2 citation statements)

References 49 publications

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“…Furthermore, the greater stability of the endo transition structure predicted for the thiophene + cyclopropene reaction 41,47 agrees with the low propensity of sulfur to act as an acceptor of hydrogen bonds. The presence of such interactions between the diene and the dienophile has also been proposed in other Diels−Alder reactions …”

Section: The Origins Of the Endo/exo Selectivity In Diels−alder React...mentioning

confidence: 75%

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Do Secondary Orbital Interactions Really Exist?

2000

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A revision of the most typical examples used to illustrate the existence of secondary orbital interactions (SOI) has been achieved. However, our analysis indicates that no conclusive evidence can be obtained from these cases. All five examples proposed by Woodward and Hoffmann in The Conservation of Orbital Symmetry have been revisited. A combination of well-known mechanisms (such as solvent effects, steric interactions, hydrogen bonds, electrostatic forces, and others) can be invoked instead to justify the endo/exo selectivity of Diels-Alder reactions.

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Section: The Origins Of the Endo/exo Selectivity In Diels−alder React...mentioning

confidence: 75%

“…The presence of such interactions between the diene and the dienophile has also been proposed in other Diels-Alder reactions. 48 Anyway, a deeper investigation into the butadiene + cylopropene cycloaddition would be necessary to ascertain the nature of the interactions existing between the reactants.…”

Section: Steric Interactionsmentioning

confidence: 99%

Do Secondary Orbital Interactions Really Exist?

2000

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Computational study of maleamic acid cyclodehydration with acetic anhydride

Constantinescu

Ivanov

2005

Int J of Quantum Chemistry

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ABSTRACT:The reaction mechanisms of N-substituted maleamic acids (MA) cyclodehydration (CDH) to the corresponding maleimides (M) and isomaleimides (IM) and IM rearrangement to M were studied by the PM3 Hamiltonian with charge model 1 (CM1P) of the AMSOL computational method with solvation effect in order to establish the most probable pathways. CDH was considered in the presence of acetic anhydride in the presence of an acetate anion or triethylamine as the dehydrating agent in CH 2 Cl 2 as the solvent. In the first step, our computational results supported carboxylic proton losses, provided by a nucleophilic center on the dehydrating agent. In the next step, maleamic acid anion could either add a molecule of a dehydrating agent (path A) or cyclicize (path B). Our results indicate the path B to require more energy than path A, so path B is considered less likely to occur. The formation (path A) of an anion complex I2 between the anion of MA and the dehydration agent was supported as well as acetate anion loss to form the neutral mixed anhydride I3. The ring closure to M or IM occurs only after I3 amide proton loss, meaning that the dehydrating agent necessitate another nucleophilic center. The cyclization of I4 anion over amide nitrogen or oxygen to the reaction outcome depends on the electronic effect of amide nitrogen substituent. The same results were obtained studying CDH of N-substituted ophthalmic acids with acetic anhydride and for MA with N,NЈ-dicyclohexylcarbodiimide as dehydrating agent, in the same solvent. In such circumstances, one can consider them the common features of a general CDH reaction mechanism of MA. Our computational results found the IM to M rearrangement to correspond to the reversible final path of synthesis mechanism although the other investigators considered it to take place under a different reaction. They also supported the importance of the acetate anion in both cyclization and rearrangement mechanisms; the presence of tertiary amine blocks the acetic acid formed during reaction, determines I3 amide proton loss and prevents rearrangement. The theoretical conclusions are consistent with the experimental results.

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Experimental and theoretical FMO interaction studies of the Diels–Alder reaction of 5-acetyl-3-methythio-1,2,4-triazine with cyclic enamines

Lipińska¹

2005

Tetrahedron

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Governing organic reactions through secondary orbital interactions. Semiempirical and density functional theory study of catalyzed cycloaddition reactions between pyrrole and ether dienophiles

Cited by 6 publications

References 49 publications

Do Secondary Orbital Interactions Really Exist?

Do Secondary Orbital Interactions Really Exist?

Computational study of maleamic acid cyclodehydration with acetic anhydride

Experimental and theoretical FMO interaction studies of the Diels–Alder reaction of 5-acetyl-3-methythio-1,2,4-triazine with cyclic enamines

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