Hyperconjugation effect on diene reactivity in 1-methyltetrazolo[5,1-a]isoindole-derived amides and thioamides

Optimized synthesis of 1-methyltetrazolo[5,1-a]isoindole-derived amides and thioamides was elaborated. Based on 13C NMR spectroscopy and X-Ray diffraction studies data, it was proposed that zwitterionic resonance structures contributed significantly to the structure of these compounds. Geometry opti...

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Bibliographic Details
Published in:Tetrahedron 2019-03, Vol.75 (13), p.2018-2026
Main Authors: Yegorova, Tatyana V., Shishkina, Svitlana V., Zubatyuk, Roman I., Tsapko, Magdalina D., Shishkin, Oleg V., Voitenko, Zoia V.
Format: Article
Language:English
Subjects:
Amides
Diels–Alder reaction
Diene reactivity
Isoindoles
n→σ hyperconjugation
Thioamides
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Summary:Optimized synthesis of 1-methyltetrazolo[5,1-a]isoindole-derived amides and thioamides was elaborated. Based on 13C NMR spectroscopy and X-Ray diffraction studies data, it was proposed that zwitterionic resonance structures contributed significantly to the structure of these compounds. Geometry optimization was performed in vacuo using m06-2x/cc-pvtz method taking into account polarizing effect of environment (PCM model) and specific intermolecular interactions. Electronic density distribution in these molecules was analyzed using NBO method. Using Δ(HOMOdiene–LUMOdienophile) for amides and thioamides in vacuo and in a protic solvent, possibility of Diels–Alder reaction was evaluated. Energies of π-π conjugation and n→σ* hyperconjugation for the amide derivative were estimated in vacuo, aprotic and protic solvents. [Display omitted]
ISSN:0040-4020
1464-5416
DOI:10.1016/j.tet.2019.02.025