AM1 semiempirical study of benzopyrroles as dienes for Diels-Alder reaction

Jursic, Branko S.

doi:10.1139/v96-015

Cited by 21 publications

(4 citation statements)

References 14 publications

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“…Jursic evaluated the reactivity of furan, pyrrole, and thiophene at the semiempirical level of theory . Based on the frontier molecular orbital (FMO) theory, it was demonstrated that although the reaction with pyrrole is facilitated when compared with Cp and furan additions, experimental reactions with pyrrole are not feasible.…”

Section: Introductionmentioning

confidence: 99%

“…Jursic evaluated the reactivity of furan, pyrrole, and thiophene at the semiempirical level of theory. 7 Based on the frontier molecular orbital (FMO) theory, it was demonstrated that although the reaction with pyrrole is facilitated when compared with Cp and furan additions, experimental reactions with pyrrole are not feasible. Later, this author studied again the reactivity of pyrrole and its derivatives as dienes in DA reactions with acetylene derivatives as dienophiles, using a mix of semiempirical and hybrid density functional theories.…”

Section: ■ Introductionmentioning

confidence: 99%

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Why Do Five-Membered Heterocyclic Compounds Sometimes Not Participate in Polar Diels–Alder Reactions?

2013

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The reactions of bicyclic enone (BCE, 1) with cyclopentadiene (Cp, 2) and the five-membered heterocyclic compounds (FHCs) furan 3 and N-methyl pyrrole 4 for the construction of polycyclic heterocyclic compounds have been studied at the B3LYP/6-31G* level. No reaction takes place in the absence of Lewis acid (LA) catalysts as a consequence of the high activation energy associated with these reactions. Electrophilic activation of BCE 1 by formation of a complex with the BF3 LA, 1-BF3, and solvent effects favor the reactions. However, a different reactivity is manifested by Cp 2 and FHCs 3 and 4. Thus, while the reaction of 1-BF3 with Cp 2 yields the expected exo [4 + 2] cycloadduct, the reactions of these FHCs yield Michael adducts. In any case, the reactions are characterized by the nucleophilic/electrophilic interaction between the most nucleophilic centers of these dienes and the most electrophilic center of complex 1-BF3. The greater ability of FHCs 3 and 4 to stabilize positive charges opposed to Cp 2 favors a stepwise mechanism with formation of a zwitterionic intermediate. Although in most stepwise Diels-Alder reactions, the subsequent ring closure has unappreciable barriers, in these FHCs the abstraction of a proton with regeneration of the aromatic ring becomes competitive. Thermodynamic calculations suggest that the exergonic character of the formation of the Michael adducts could be the driving force for the reactions involving FHCs.

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Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Why Do Five-Membered Heterocyclic Compounds Sometimes Not Participate in Polar Diels–Alder Reactions?

2013

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“…[5][6][7] It was demonstrated 8,9 that the DFT B3LYP is a reliable method for the calculation of geometries and energies of benzofused heterocycles. The optimized geometries and calculated electron density parameters of benzodiazepines, benzothiophene, benzofuran were estimated in order to determine their reactivity in electrophilic substitution and Diels-Alder reactions.…”

Section: Methodsmentioning

confidence: 99%

A theoretical approach to the nucleophilic behavior of benzofused thieno[3,2-b]furans using DFT and HF based reactivity descriptors

Vektarienė¹,

Vektaris²,

Svoboda³

2009

Arkivoc

131

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Calculations of traditional HF and DFT based reactivity descriptors are reported for the isomeric benzofused thieno [3,2-b]furans in order to get insight into the factors determining the nature of their interactions with electrophiles. Global reactivity descriptors such as ionization energy, molecular hardness, electrophilicity, frontier molecular orbital energies and shapes, the condensed Fukui functions, total energies were determined and used to identify the differences in the stability and reactivity of benzofused thieno[3,2-b]furans. Additionally the bond order uniformity analysis, local ionization energy and electrostatic potential energy surfaces revealed structural differences of isomeric thieno[3,2-b]furans. Calculated values lead to the conclusion that heterocyclic system in thieno [3,2-b]benzofuran is more aromatic and stable than in isomeric benzothieno [3,2-b]furan. Theoretical results are in complete agreement with the experimental results and show exceptional reactivity of C(2) atom for both isomers.

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“…Alternatively, 20 could be prepared by in-situ-generated benzyne cycloaddition with pyrrole 1 (84%). Preparation of a nitro derivative of 20 was achieved by in-situ generation of 4-nitro benzyne from iodonium salt 22 [20] and its reaction with pyrrole 1, which provided cycloadduct 23 in 32% yield. These reactions show that the reactivity of pyrrole-1-carboxamidine 1 could be increased by the presence of a highly reactive dienophile such as arynes.…”

Section: Synthesis Of Isoindoles and Their Reactivitymentioning

confidence: 99%

N,N′-Di-Boc-2H-Isoindole-2-carboxamidine—First Guanidine-Substituted Isoindole

2022

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Synthesis of N,N′-Di-Boc-2H-isoindole-2-carboxamidine, the first representative of isoindoles containing guanidine functionality, was carried out. The cycloaddition reactivity of this new Diels–Alder heterodiene was studied and the title compound was employed as a cycloaddition delivery reagent for guanidine functionality. Higher reactivity was found in comparison with the corresponding pyrrole derivative. Substitution with fluorine or guanidine functionality does not change the reactivities of isoindoles, and these findings are in good accord with computational results.

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AM1 semiempirical study of benzopyrroles as dienes for Diels-Alder reaction

Cited by 21 publications

References 14 publications

Why Do Five-Membered Heterocyclic Compounds Sometimes Not Participate in Polar Diels–Alder Reactions?

Why Do Five-Membered Heterocyclic Compounds Sometimes Not Participate in Polar Diels–Alder Reactions?

A theoretical approach to the nucleophilic behavior of benzofused thieno[3,2-b]furans using DFT and HF based reactivity descriptors

N,N′-Di-Boc-2H-Isoindole-2-carboxamidine—First Guanidine-Substituted Isoindole

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