IJIAS-13-292-25.pdf - International Journal of Innovation and Applied Studies ISSN 2028\u20109324 Vol 5 No 2 Feb 2014 pp 120\u2010130 \u00a9 2014 Innovative Space

IJIAS-13-292-25.pdf - International Journal of Innovation...

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International Journal of Innovation and Applied Studies ISSN 2028‐9324 Vol. 5 No. 2 Feb. 2014, pp. 120‐130 © 2014 Innovative Space of Scientific Research Journals Corresponding Author: Abdeslam El Hajbi ([email protected]) 120 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) [ Theoretical study of regioselectivity and stereoselectivity of condensation of β-himachalene with dichlorocarbene using density functional theory (DFT) ] Abdellah Zeroual 1 , Mohammed El Idrissi 1 , Ahmed Benharref 2 , and Abdeslam El Hajbi 1 1 Laboratoire de Chimie Physique, Département de Chimie, Faculté des Sciences, Université Chouaïb Doukkali, El Jadida, Morocco 2 Laboratoire de Chimie Biomoléculaire, Substances Naturelles et Réactivité, URAC 16, Faculté des Sciences Semlalia, Université Cadi Ayyad, Marrakech, Morocco 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 : 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[6,4,0,0 1.3 ]dodec‐9‐ene, also referred to as dichlorocarbene β‐himachalene α (referred to as P 1 here), formed by reaction at the α side of the C 6 =C 7 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 C 6 =C 7 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[6,5,0,0 1.2 ,0 9.11 ]tridecane and (1S,3R,8R,9R,11S)‐3,7,7,11‐tetrachloro‐3,7,7,11‐tetramethyltetracyclo[6,5,0,0 1.2 ,0 9.11 ]tridecane (referred to here as P 2 and P 3 respectively). The same two products are also obtained when P 1 reacts with one equivalent of dichlorocarbene. The attack takes place simultaneously at the α and β sides of the C 2 =C 3 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. P 3 is formed in greater quantity than P 2 . K EYWORDS : Chemical potential, chemospecificity, electrophil, exothermic reaction, frontier orbital, nucleophil, relative energy, transition state. R ESUME : Le β‐himachalène se comporte comme nucléophile alors que le dichlorocarbène se comporte comme électrophile.
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