ChemInform Abstract: SOLVENT EFFECT ON STEREOSELECTIVITY AND REGIOSELECTIVITY DURING THE DIELS‐ALDER REACTION BETWEEN TRANS‐1,3‐PENTADIENE AND ACRYLONITRILE

Nakagawa, Kazuyuki; Iwase, Shoutaro; Ishii, Youichi; Hamanaka, Sawako; Ogawa, Masahi

doi:10.1002/chin.197940165

Cited by 2 publications

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“…The Diels−Alder cycloaddition between acrylonitrile and piperylene follows a behavior pattern similar to that of the corresponding reaction with cyclopentadiene (Scheme ) . Thus, a preference for the ortho-trans adduct (corresponding to an exo approach) is found in benzene solution, whereas the ortho-cis product (formed via an endo transition state) is favored in polar solvents (e.g., methanol, ethanol, and acetone).…”

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

confidence: 76%

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: 76%

Do Secondary Orbital Interactions Really Exist?

2000

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“…Therefore, the results of and are in agreement with the experimental results and the predicted regioselectivities of and are obviously not consistent with the experimental results. [ 1‐8 ] In addition, both equilibrium geometry and reactivity index were also calculated by MP2 method, but the obtained regioselectivities were also not agreed with the experiments totally (Table S3).…”

Section: Results and Disccusionmentioning

confidence: 95%

“…Experimentally, in the reaction of a monosubstituted olefin with a 1‐substituted diene, predominance of ortho cycloadduct is to be expected. [ 1‐22 ] In this respect, the regioselectivities of the D‐A reactions of 1‐substituted dienes with unsymmetrical dienophile ( to 58) will be predicted according to the local HSAB principle. The local softness and the GLS were obtained by ab initio method at the level of MP2/6‐311++G(d,p) with the finite difference approximation (only at atomic level) and ABEEMσπ model (at both atomic and π‐bond levels), respectively.…”

Section: Results and Disccusionmentioning

confidence: 99%

“…These results are in good agreement with the experimental results. [ 1‐8 ]…”

Section: Results and Disccusionmentioning

confidence: 99%

“…Because of good regio‐ and stereoselectivity, D‐A reactions between unsymmetrical dienes and dienophiles have been studied in various experimental [ 1‐25 ] and theoretical methods. [ 24,26‐33 ] Especially, D‐A reactions in pericyclic reactions were gained widespread investigations by the conceptual density functional theory (CDFT).…”

Section: Background and Originality Contentmentioning

confidence: 99%

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Theoretical Investigation on Regioselectivities of Diels‐Alder Reactions by Conjugated Effect

Zhao

et al. 2020

Chin. J. Chem.

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of main observation and conclusion The regioselectivities of 76 Diels-Alder reactions between unsymmetrical dienes and dienophiles were investigated by local softness and generalized local softness at atomic and chemical bond view, respectively, where the reactivity descriptors were calculated by finite difference approximation and ABEEMσπ model. Based on local HSAB principle and matching criterion of local softness, reasonable explanation and prediction on regioselectivities of all reactions through ABEEMσπ model have been obtained, which are in agreement with the experimental results. Especially, at π-bond level, while the 1-substituents of dienes were NH2, NMe2, and NEt2, because of the p-π conjugated effect between the lone pairs of N atom and the conjugated π-bond of the four double-bonded carbon atoms in diene, it made the dienophile not easy to approach diene by Manner A, hence, Manner B can forecast the ortho regioisomer as main product well, and Manner A cannot. As to the other reactions, both Manner A and Manner B can predict their regioselectivities. It can be seen that the ABEEMσπ model can take the effect of the chemical environment on the reaction reactivity into account richly, especially the system includes π-bond and lone pairs. However, the results through the finite difference approximation are not reasonable. Background and Originality Content Diels-Alder (D-A) reaction is one of the most useful synthetic reactions, and its overwhelming importance is well known in organic synthesis of six-membered functionalized carbocyclic compounds. The usefulness of D-A reaction arises from its versatility and from its remarkable regio-and stereoselectivity. The reaction between unsymmetrical diene and dienophile can produce two isomeric adducts depending on the orientation of the substituents in the dienes, as shown in Figure 1.

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ChemInform Abstract: SOLVENT EFFECT ON STEREOSELECTIVITY AND REGIOSELECTIVITY DURING THE DIELS‐ALDER REACTION BETWEEN TRANS‐1,3‐PENTADIENE AND ACRYLONITRILE

Abstract: Die Diels‐Alder‐Reaktion von trans‐ Pentadien‐1,3 (I) mit Acrylnitril (II) liefert in Abhängigkeit von der Polarität des verwendeten Lösungsmittels die vier isomeren Cycloaddukte (III)‐(VI).

Cited by 2 publications

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Do Secondary Orbital Interactions Really Exist?

Do Secondary Orbital Interactions Really Exist?

Theoretical Investigation on Regioselectivities of Diels‐Alder Reactions by Conjugated Effect

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