[ Étude théorique de la regiosélectivité et la stéreosélectivité de la condensation du β-himachalène avec le dichlorocarbène par la théorie de la fonctionnelle de la densité (DFT) ]
Volume 5, Issue 2, February 2014, Pages 120–130
Abdellah Zeroual1, Mohammed El Idrissi2, Ahmed Benharref3, and Abdeslam El Hajbi4
1 Laboratory of Physical Chemistry, Department of Chemistry, Faculty of Science, Chouaib Doukkali University BP 20, 24000, El Jadida, Morocco
2 Laboratory of Physical Chemistry, Department of Chemistry, Faculty of Science, Chouaib Doukkali University BP 20, 24000, El Jadida, Morocco
3 Laboratoire de Chimie Biomoléculaire, Substances Naturelles et Réactivité, URAC 16, Faculté des Sciences Semlalia, Université Cadi Ayyad, Marrakech, Morocco
4 Laboratory of Physical Chemistry, Department of Chemistry, Faculty of Science, Chouaib Doukkali University BP 20, 24000, El Jadida, Morocco
Original language: French
Copyright © 2014 ISSR Journals. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
β-himachalene behaves as a nucleophile while dichlorocarbene behaves as an electrophile. Equimolar condensation of β-himachalene and dichlorocarbene results in a single product: (1S,3R,8R)-2,2-dichloro-3,7,7,10-tetramethyltricyclo[6,4,0,01.3]dodec-9-ene, also referred to as dichlorocarbene β-himachalene ? (referred to as P1 here), formed by reaction at the ? side of the C6=C7 double bond of β-himachalene. This regioselectivity is controlled by the frontier orbitals, as is the reaction mechanism. Electron density is particularly high around the C6=C7 double bond of the HOMO orbital. However when β-himachalene reacts with two equivalents of dichlorocarbene under the same conditions the result is two products: (1S,3R,8R,9S,11R)-2,2,10,10-tetrachloro-3,7,7,11-tetramethyltetracyclo[6,5,0,01.2,09.11]tridecane and (1S,3R,8R,9R,11S)-3,7,7,11-tetrachloro-3,7,7,11-tetramethyltetracyclo[6,5,0,01.2,09.11]tridecane (referred to here as P2 and P3 respectively). The same two products are also obtained when P1 reacts with one equivalent of dichlorocarbene. The attack takes place simultaneously at the ? and β sides of the C2=C3 double bond. Study of the two reactions using the ab-initio quantum density functional theory method (B3LYP/6-31G(d)) shows that they are stereoselective, chemospecific, concerted and exothermic. P3 is formed in greater quantity than P2.
Author Keywords: Chemical potential, chemospecificity, electrophil, exothermic reaction, frontier orbital, nucleophil, relative energy, transition state.
Volume 5, Issue 2, February 2014, Pages 120–130
Abdellah Zeroual1, Mohammed El Idrissi2, Ahmed Benharref3, and Abdeslam El Hajbi4
1 Laboratory of Physical Chemistry, Department of Chemistry, Faculty of Science, Chouaib Doukkali University BP 20, 24000, El Jadida, Morocco
2 Laboratory of Physical Chemistry, Department of Chemistry, Faculty of Science, Chouaib Doukkali University BP 20, 24000, El Jadida, Morocco
3 Laboratoire de Chimie Biomoléculaire, Substances Naturelles et Réactivité, URAC 16, Faculté des Sciences Semlalia, Université Cadi Ayyad, Marrakech, Morocco
4 Laboratory of Physical Chemistry, Department of Chemistry, Faculty of Science, Chouaib Doukkali University BP 20, 24000, El Jadida, Morocco
Original language: French
Copyright © 2014 ISSR Journals. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
β-himachalene behaves as a nucleophile while dichlorocarbene behaves as an electrophile. Equimolar condensation of β-himachalene and dichlorocarbene results in a single product: (1S,3R,8R)-2,2-dichloro-3,7,7,10-tetramethyltricyclo[6,4,0,01.3]dodec-9-ene, also referred to as dichlorocarbene β-himachalene ? (referred to as P1 here), formed by reaction at the ? side of the C6=C7 double bond of β-himachalene. This regioselectivity is controlled by the frontier orbitals, as is the reaction mechanism. Electron density is particularly high around the C6=C7 double bond of the HOMO orbital. However when β-himachalene reacts with two equivalents of dichlorocarbene under the same conditions the result is two products: (1S,3R,8R,9S,11R)-2,2,10,10-tetrachloro-3,7,7,11-tetramethyltetracyclo[6,5,0,01.2,09.11]tridecane and (1S,3R,8R,9R,11S)-3,7,7,11-tetrachloro-3,7,7,11-tetramethyltetracyclo[6,5,0,01.2,09.11]tridecane (referred to here as P2 and P3 respectively). The same two products are also obtained when P1 reacts with one equivalent of dichlorocarbene. The attack takes place simultaneously at the ? and β sides of the C2=C3 double bond. Study of the two reactions using the ab-initio quantum density functional theory method (B3LYP/6-31G(d)) shows that they are stereoselective, chemospecific, concerted and exothermic. P3 is formed in greater quantity than P2.
Author Keywords: Chemical potential, chemospecificity, electrophil, exothermic reaction, frontier orbital, nucleophil, relative energy, transition state.
Abstract: (french)
Le β-himachalène se comporte comme nucléophile alors que le dichlorocarbène se comporte comme électrophile. Le β-himachalène réagit avec un équivalent de dichlorocarbène pour donner un seul produit: (1S,3R,8R)-2,2-dichloro-3,7,7,10-tetramethyltricyclo[6,4,0,01.3]dodec-9-ene (noté P1), résultant de l'attaque de la double liaison C6=C7 du β-himachalène en face α. Cette régiosélectivité et le mécanisme réactionnel sont contrôlés par les orbitales frontières. La carte d'isodensité de l'orbitale moléculaire HOMO est très condensée au niveau de la double liaison C6=C7. Par contre le traitement du β-himachalène par deux équivalents de dichlorocarbène dans les mêmes conditions conduit à deux produits tétra-chlorés (1S,3R,8R,9S,11R)-2,2,10,10-tetrachloro-3,7,7,11-tetramethyltetracyclo[6,5,0,01.2,09.11]tridecane et (1S,3R,8R,9R,11S)-3,7,7,11-tetrachloro-3,7,7,11-tetramethyltetracyclo[6,5,0,01.2,09.11]tridecane (notés P2 et P3 respectivement). Ces deux produits sont également obtenus par l'attaque d'un équivalent de dichlorocarbène du produit P1. L'attaque se fait simultanément en face α et β de la double liaison C2=C3. L'étude de ces deux réactions par la méthode quantique ab-initio théorie de la fonctionnelle de la densité B3LYP/6-31G(d) montre qu'elles sont stéréosélectives, chimiospécifiques, concertées et exothermiques. Le produit P3 est majoritaire par rapport au P2.
Author Keywords: Chimiospécificité, électrophile, énergie relative, état de transition, nucléophile, orbitale frontière, potentiel chimique, réaction exothermique.
How to Cite this Article
Abdellah Zeroual, Mohammed El Idrissi, Ahmed Benharref, and Abdeslam El Hajbi, “Theoretical study of regioselectivity and stereoselectivity of condensation of β-himachalene with dichlorocarbene using density functional theory (DFT),” International Journal of Innovation and Applied Studies, vol. 5, no. 2, pp. 120–130, February 2014.
