Regio and stereochemical probes of iodine interactions in diiodocyclododecanes

Cyclododecane preferentially adopts a square-like geometry, giving rise to corner and edge methylene (CH2) groups, whose hydrogens assume different orientations. In CH2 can be inward- (endo) outward-looking (exo) the ring. Herein, we have quantum-chemically studied replacement of two in cyclododecane with iodines at relative positions 1,4, 1,5, 1,6, 1,7. Intramolecular interactions are only slightly unfavorable 1,7-diiodocyclododecane containing organic edge/endo positions, less than expected from steric considerations. This behavior was discussed terms transannular interactions, numerical estimation for magnitude intramolecular interaction energy has been performed based on an isodesmic reaction scheme by natural decomposition analysis. 1,5-Diiodocyclododecane both endo orientation (occupying opposite faces ring) is strongly favored (by ca. 2.0 kcal mol−1) compared respective monosubstituted counterparts, due highly stabilizing hyperconjugative interactions. Although halogen bonding involving anionic species widely known, show that halogens, particular iodine, useful stereochemical control macrocycles.