International Journal of Innovation and Applied Studies ISSN 2028-9324 Vol. 6 No. 4 July 2014, pp. 734-745 © 2014 Innovative Space of Scientific Research Journals Corresponding Author: Abdeslam El Hajbi 734 Étude théorique de la chimio-, régio- et stéréosélectivité de l’interaction entre l’α-trans-himachalène et le dichlorocarbène par la méthode de la théorie de la fonctionnelle de la densité (DFT) B3LYP/6-311G (d, p) [ Theoretical study of the chemo-, regio- and stereoselectivity of the interaction between dichlorocarbene and α-trans-himachalene using density functional theory (DFT) B3LYP/6-31G (d, p) ] Redouan Hammal 1 , Ahmed Benharref 2 , and Abdeslam El Hajbi 1 1 Laboratoire de Chimie-Physique, Département de Chimie, Faculté des Sciences, Université Chouaïb Doukkali, BP 20, 24000 El Jadida, Maroc 2 Laboratoire de Chimie Biomoléculaire Substances Naturelles et Réactivité (URAC 16), Université Cadi Ayyad, Faculté des Sciences Semlalia, BP 2390, Marrakech, Maroc 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. A BSTRACT : The reaction between α-trans-himachalene and dichlorocarbene has been studied using density functional theory (DFT) B3LYP/6-311G (d, p). The global electrophilicity and global nucleophilicity indices indicate that α-trans-himachalene behaves as a nucleophile while dichlorocarbene behaves as an electrophile. The majority product obtained by stoichiometric reaction between dichlorocarbene and α-trans-himachalene is (1R, 2S, 4R, 7S)-3,3-dichloro-8-methylene-4,12,12-trimethyl- tricyclo [18.104.22.168 2,4 ] dodecane (referred to here as P 1 (α)): in this reaction the attack takes place at the endocyclic double bond at the α side of α-trans-himachalene. The majority product obtained by the reaction between two equivalents of dichlorocarbene with α-trans-himachalene is (1R, 2S, 4R, 7S, 8R)-3,3,13,13-tetrachloro-4,12,12-trimethyl-tricyclo [22.214.171.124 2,4 ] - spiro[2 8 ] tetradecane (referred to here as P 2 (β)): here the attack takes place at the β side of the exocyclic double bond. P 2 (β) is also obtained by the equimolar reaction of P 1 (α) with dichlorocarbene. P 1 (α) and P 2 (β) are both exothermic. Analysis of local electrophilicity and local nucleophilicity indices demonstrates the chemo-, regio- and stereoselectivity of the reaction. Analysis of the potential energy surface shows that this reaction follows an asynchronous concerted mechanism. Calculating the intrinsic reaction coordinate (IRC) shows that the reaction mechanism can be characterized as "one-step" and "two- stage". Stationary points were characterized by frequency calculations in order to verify that the transition states had one and only one imaginary frequency.
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