A theoretical study of the structure, charge distribution and gas-phase basicity of azaindoles
Identifieur interne : 004001 ( Main/Exploration ); précédent : 004000; suivant : 004002A theoretical study of the structure, charge distribution and gas-phase basicity of azaindoles
Auteurs : J. Catalán [Espagne] ; O. M [Espagne] ; P. Pérez [Espagne] ; M. Yá Ez [Espagne]Source :
- Tetrahedron [ 0040-4020 ] ; 1982.
Abstract
We have carried out ab initio calculations, using a STO-3G minimal basis set, for indazole, benzimidazole, azaindoles and their tautomeric forms. The structural changes which take place in the exchange of the imino proton are fully analized and explained in terms of hybridization effects, valence-shell electron-pairs repulsions and intramolecular non-bonded interactions. These structural changes affect substantially to the endocyclic bond angles which involved both N's. The structure and the charge distribution of the 5-membered ring of azaindoles is very little affected by the position of the aza N. The dicoordinated nitrogen atom is more negative than the tricoordinated one (with the exception of 1H-indazole). As in indoles, C3 of azaindoles is the C atom with the highest electronic density. The prototropic tautomerism in these species is accompanied by a strong migration of charge from the 6 to the 5-membered ring, which results in a considerable increase of the polarity and the basicity of the corresponding tautomeric forms. The predicted PA's are in good agreement with the experimental evidence. C5 is the most reactive C atom of indazole and benzimidazole, although in the former C3 is almost as active as C5. In azaindoles the most basic C atom is C3. Azaindoles are less reactive than indole toward electrophilic agents. Our predicted PA's for N protonation present differences much smaller than those observed in solution. We propose, as a possible explanation, an influence of the tautomeric forms which are more basic in the gas-phase, and more easy to stabilize in aqueous solution, than the normal ones.
Url:
DOI: 10.1016/S0040-4020(01)82458-3
Affiliations:
Links toward previous steps (curation, corpus...)
- to stream Istex, to step Corpus: 002873
- to stream Istex, to step Curation: 002674
- to stream Istex, to step Checkpoint: 003153
- to stream Main, to step Merge: 004200
- to stream Main, to step Curation: 004001
Le document en format XML
<record><TEI wicri:istexFullTextTei="biblStruct"><teiHeader><fileDesc><titleStmt><title>A theoretical study of the structure, charge distribution and gas-phase basicity of azaindoles</title><author><name sortKey="Catalan, J" sort="Catalan, J" uniqKey="Catalan J" first="J." last="Catalán">J. Catalán</name></author><author><name sortKey="M, O" sort="M, O" uniqKey="M O" first="O." last="M">O. M</name></author><author><name sortKey="Perez, P" sort="Perez, P" uniqKey="Perez P" first="P." last="Pérez">P. Pérez</name></author><author><name sortKey="Ya Ez, M" sort="Ya Ez, M" uniqKey="Ya Ez M" first="M." last="Yá Ez">M. Yá Ez</name></author></titleStmt><publicationStmt><idno type="wicri:source">ISTEX</idno><idno type="RBID">ISTEX:38BCCD87C36EFF1CB5CA0BEF061E8CBCA8737B11</idno><date when="1983" year="1983">1983</date><idno type="doi">10.1016/S0040-4020(01)82458-3</idno><idno type="url">https://api.istex.fr/document/38BCCD87C36EFF1CB5CA0BEF061E8CBCA8737B11/fulltext/pdf</idno><idno type="wicri:Area/Istex/Corpus">002873</idno><idno type="wicri:Area/Istex/Curation">002674</idno><idno type="wicri:Area/Istex/Checkpoint">003153</idno><idno type="wicri:doubleKey">0040-4020:1983:Catalan J:a:theoretical:study</idno><idno type="wicri:Area/Main/Merge">004200</idno><idno type="wicri:Area/Main/Curation">004001</idno><idno type="wicri:Area/Main/Exploration">004001</idno></publicationStmt><sourceDesc><biblStruct><analytic><title level="a">A theoretical study of the structure, charge distribution and gas-phase basicity of azaindoles</title><author><name sortKey="Catalan, J" sort="Catalan, J" uniqKey="Catalan J" first="J." last="Catalán">J. Catalán</name><affiliation wicri:level="4"><country xml:lang="fr">Espagne</country><wicri:regionArea>Departamento de Química Física y Química Cuántica, Centro Coordinado CSIC-UAM, Facultad de Ciencias, C-XIV, Universidad Autónoma de Madrid, Cantoblanco</wicri:regionArea><orgName type="university">Université autonome de Madrid</orgName><placeName><settlement type="city">Madrid</settlement><region nuts="2" type="region">Communauté de Madrid</region></placeName></affiliation></author><author><name sortKey="M, O" sort="M, O" uniqKey="M O" first="O." last="M">O. M</name><affiliation wicri:level="4"><country xml:lang="fr">Espagne</country><wicri:regionArea>Departamento de Química Física y Química Cuántica, Centro Coordinado CSIC-UAM, Facultad de Ciencias, C-XIV, Universidad Autónoma de Madrid, Cantoblanco</wicri:regionArea><orgName type="university">Université autonome de Madrid</orgName><placeName><settlement type="city">Madrid</settlement><region nuts="2" type="region">Communauté de Madrid</region></placeName></affiliation></author><author><name sortKey="Perez, P" sort="Perez, P" uniqKey="Perez P" first="P." last="Pérez">P. Pérez</name><affiliation wicri:level="4"><country xml:lang="fr">Espagne</country><wicri:regionArea>Departamento de Química Física y Química Cuántica, Centro Coordinado CSIC-UAM, Facultad de Ciencias, C-XIV, Universidad Autónoma de Madrid, Cantoblanco</wicri:regionArea><orgName type="university">Université autonome de Madrid</orgName><placeName><settlement type="city">Madrid</settlement><region nuts="2" type="region">Communauté de Madrid</region></placeName></affiliation></author><author><name sortKey="Ya Ez, M" sort="Ya Ez, M" uniqKey="Ya Ez M" first="M." last="Yá Ez">M. Yá Ez</name><affiliation wicri:level="4"><country xml:lang="fr">Espagne</country><wicri:regionArea>Departamento de Química Física y Química Cuántica, Centro Coordinado CSIC-UAM, Facultad de Ciencias, C-XIV, Universidad Autónoma de Madrid, Cantoblanco</wicri:regionArea><orgName type="university">Université autonome de Madrid</orgName><placeName><settlement type="city">Madrid</settlement><region nuts="2" type="region">Communauté de Madrid</region></placeName></affiliation></author></analytic><monogr></monogr><series><title level="j">Tetrahedron</title><title level="j" type="abbrev">TET</title><idno type="ISSN">0040-4020</idno><imprint><publisher>ELSEVIER</publisher><date type="published" when="1982">1982</date><biblScope unit="volume">39</biblScope><biblScope unit="issue">17</biblScope><biblScope unit="page" from="2851">2851</biblScope><biblScope unit="page" to="2861">2861</biblScope></imprint><idno type="ISSN">0040-4020</idno></series><idno type="istex">38BCCD87C36EFF1CB5CA0BEF061E8CBCA8737B11</idno><idno type="DOI">10.1016/S0040-4020(01)82458-3</idno><idno type="PII">S0040-4020(01)82458-3</idno></biblStruct></sourceDesc><seriesStmt><idno type="ISSN">0040-4020</idno></seriesStmt></fileDesc><profileDesc><textClass></textClass><langUsage><language ident="en">en</language></langUsage></profileDesc></teiHeader><front><div type="abstract" xml:lang="en">We have carried out ab initio calculations, using a STO-3G minimal basis set, for indazole, benzimidazole, azaindoles and their tautomeric forms. The structural changes which take place in the exchange of the imino proton are fully analized and explained in terms of hybridization effects, valence-shell electron-pairs repulsions and intramolecular non-bonded interactions. These structural changes affect substantially to the endocyclic bond angles which involved both N's. The structure and the charge distribution of the 5-membered ring of azaindoles is very little affected by the position of the aza N. The dicoordinated nitrogen atom is more negative than the tricoordinated one (with the exception of 1H-indazole). As in indoles, C3 of azaindoles is the C atom with the highest electronic density. The prototropic tautomerism in these species is accompanied by a strong migration of charge from the 6 to the 5-membered ring, which results in a considerable increase of the polarity and the basicity of the corresponding tautomeric forms. The predicted PA's are in good agreement with the experimental evidence. C5 is the most reactive C atom of indazole and benzimidazole, although in the former C3 is almost as active as C5. In azaindoles the most basic C atom is C3. Azaindoles are less reactive than indole toward electrophilic agents. Our predicted PA's for N protonation present differences much smaller than those observed in solution. We propose, as a possible explanation, an influence of the tautomeric forms which are more basic in the gas-phase, and more easy to stabilize in aqueous solution, than the normal ones.</div></front></TEI><affiliations><list><country><li>Espagne</li></country><region><li>Communauté de Madrid</li></region><settlement><li>Madrid</li></settlement><orgName><li>Université autonome de Madrid</li></orgName></list><tree><country name="Espagne"><region name="Communauté de Madrid"><name sortKey="Catalan, J" sort="Catalan, J" uniqKey="Catalan J" first="J." last="Catalán">J. Catalán</name></region><name sortKey="M, O" sort="M, O" uniqKey="M O" first="O." last="M">O. M</name><name sortKey="Perez, P" sort="Perez, P" uniqKey="Perez P" first="P." last="Pérez">P. Pérez</name><name sortKey="Ya Ez, M" sort="Ya Ez, M" uniqKey="Ya Ez M" first="M." last="Yá Ez">M. Yá Ez</name></country></tree></affiliations></record>Pour manipuler ce document sous Unix (Dilib)
EXPLOR_STEP=$WICRI_ROOT/Ticri/CIDE/explor/OcrV1/Data/Main/Exploration
HfdSelect -h $EXPLOR_STEP/biblio.hfd -nk 004001 | SxmlIndent | more
Ou
HfdSelect -h $EXPLOR_AREA/Data/Main/Exploration/biblio.hfd -nk 004001 | SxmlIndent | more
Pour mettre un lien sur cette page dans le réseau Wicri
{{Explor lien
|wiki= Ticri/CIDE
|area= OcrV1
|flux= Main
|étape= Exploration
|type= RBID
|clé= ISTEX:38BCCD87C36EFF1CB5CA0BEF061E8CBCA8737B11
|texte= A theoretical study of the structure, charge distribution and gas-phase basicity of azaindoles
}}
| This area was generated with Dilib version V0.6.32. |  |