ANALYSE MULTICONFORMATIONNELLE DES MACROLIDES SYMÉTRIQUES DE 12 À 28 CHAÎNONS BASÉE SUR LA MÉCANIQUE MOLÉCULAIRE
BELAIDI S. 1, LABBASSI M. 2, GRÉE R. 3 ET BOTREL A. 3 (1)DÉPARTEMENT DE CHIMIE, UNIVERSITÉ D’OUARGLA, B.P. 511, 30000, OUARGLA, ALGÉRIE. S_BELAIDI@YAHOO.FR (2)DÉPARTEMENT DE CHIMIE, UNIVERSITÉ D’ELHADJ LAKHDAR-BATNA, 05000 BATNA, ALGÉRIE. (3)ECOLE NATIONALE SUPÉRIEURE DE CHIMIE DE RENNES, AVENUE DU GÉNÉRAL L
In this paper, we studied the a,Ăź-unsaturated macrolides, which represent the binding structure for many antibiotic families from 12- to 28- membered rings. Our object is to determine preferred conformations of macrocycles and to examine the relative importance of different contributions to total steric energy. The strain energy per CH2 group is relatively higher for macrocycle 12 (m = 4) (E(st/n) = 4.77 Kcal/mol). An important decrease in the strain energy per CH2 group from m = 4 to m = 6 confirms perfectly the limit between the two classes of medium and large rings. For two adjoining macrolides the torsional energy is lower for (m) uneven as in the case of the strain energy for m= 6. The contribution of the Van der Waals energy E (VdW /m) is higher in all examined macrocycles in their stable conformers (m = 6). The most preferential conformer (m = 12) for rings with n even belongs to the F6 family, then for n uneven it belongs to the F5 family; where as for m >12, this one is family 4.
