Do Secondary Orbital Interactions Really Exist?

Garcı́a, José I.; Mayoral, José A.; Salvatella, Luis

doi:10.1021/ar0000152

Cited by 156 publications

(100 citation statements)

References 57 publications

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“…The cyclohexene product formed in the Diels-Alder reaction can exist as one of two diastereomeric compounds ( Figure 26). The so-called endo-product is kinetically favored and involves secondary orbital interactions between the two unreactive C atoms on the diene and the π orbitals of the neighboring C=O groups on the alkene [236]. In comparison, the exo-product is accessible through thermodynamic control.…”

Section: Lewis-acid Catalyzed Diels-alder Reaction Between Maleicmentioning

confidence: 99%

Theoretical Studies of Substitutionally Doped Single-Walled Nanotubes

Yeung

Chen

Wang

2010

Journal of Nanotechnology

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The rich chemistry of single-walled carbon nanotubes (SWCNTs) is enhanced by substitutional doping, a process in which a single atom of the nanotube sidewall is replaced by a heteroatom. These so-called heteroatom-substituted SWCNTs (HSWCNTs) exhibit unique chemical and physical properties not observed in their corresponding undoped congeners. Herein, we present theoretical studies of both main group element and transition metal-doped HSWCNTs. Within density functional theory (DFT), we discuss mechanistic details of their proposed synthesis from vacancy-defected SWCNTs and describe their geometric and electronic properties. Additionally, we propose applications for these nanomaterials in nanosensing, nanoelectronics, and nanocatalysis.

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Section: Lewis-acid Catalyzed Diels-alder Reaction Between Maleicmentioning

confidence: 99%

Theoretical Studies of Substitutionally Doped Single-Walled Nanotubes

Yeung

Chen

Wang

2010

Journal of Nanotechnology

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“…However, the endo/exo selectivity is more likely due to a combination of effects, including solvent effects, steric interactions, hydrogen bonds and electrostatic forces. 66 …”

Section: Stereoselectivitymentioning

confidence: 99%

Asymmetric 1,3-dipolar cycloadditions of acrylamides

2010

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This critical review, which is relevant to researchers in synthetic organic chemistry, focuses on asymmetric 1,3-dipolar cycloadditions with acrylamides. The use of chiral acrylamides as dipolarophiles leads to high levels of stereocontrol, due to conformational constraint in the acrylamides. Employment of chiral tertiary acrylamides containing nitrogen heterocycles is particularly effective in controlling the stereoselectivity. Following a general overview of 1,3-dipolar cycloadditions, the main body of the review focuses on asymmetric 1,3-dipolar cycloadditions of acrylamides with nitrile oxides, nitrones, diazoalkanes and azomethine ylides, with particular emphasis on the rationale for the observed stereocontrol (215 references)

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“…O conceito de interações secundárias de orbitais, utilizado para explicar a preferên-cia cinética do estado de transição endo sobre o exo, foi questionado e logo a seguir defendido. 26,27 Um exemplo importante da relevância de cálculos aparece no caso da primeira reação estudada, entre ciclopentadieno e parabenzoquinona (Esquema 1). Inicialmente, Albrecht e outros atribuíram estruturas de adição nucleofílica 1,4 e cicloadição [2+2] e, finalmente, Diels e Alder propuseram a estrutura correta sem definir a estereoquímica relativa.…”

Section: O Mecanismo E Aspectos Teóricosunclassified