Crystal structures of three isomeric 4-[3-(dichlorophenyl)-hexahydro[1,3]oxazolo[3,4-a]pyridin-1-yl]-2,8-bis(trifluoromethyl) quinolines: importance of cage-type and pi(quinoline)center dot center dot center dot pi(quinoline) dimeric motifs

摘要

The crystal structures of three isomeric 4-[3-(dichlorophenyl)-hexahydro[1,3]oxazolo[3,4-a]pyridin- 1-yl]-2,8-bis(trifluoromethyl) quinolines, (5: X-2 = 2,3-, 2,4- and 2,5-Cl-2) have been determined and have been compared to those of related compounds. The crystallographic asymmetric unit of each of (5: X-2 = 2,4-Cl-2) and (5: X-2 = 3,4-Cl-2) consists of a single molecule, while that of (5: X-2 = 2,3-Cl-2) contains two independent molecules - Molecule A and Molecule B. Each of the three compounds crystallizes in the triclinic space group, P (1) over bar. The supramoleular arrangements of the three compounds are generated from combinations of some of C-H center dot center dot center dot X (X = F, Cl, and O), C-X center dot center dot center dot pi (X = H, F and Cl) and pi center dot center dot center dot pi interactions. The presence and significance of two centrosymmetric structural dimeric motives - cage-type dimers, formed (i) from the intermeshing of "F"-shaped monomers, and (ii) pi(quinoline)center dot center dot center dot pi(quinoline) interactions, reported to arise frequently in other 4-[3-aryl-hexahydro[1,3] oxazolo[3,4-a] pyridin-1-yl]-2,8-bis(trifluoromethyl)quinolone compounds, were investigated. Both (5: X-2 = 2,4-Cl-2) and (5: X-2 = 3,4-Cl-2) exhibit cage-type dimers. In the cases of molecule B of (5: X-2 = 2,3-Cl-2) and (5: X-2 = 3,4-Cl-2), the pi(quinoline)center dot center dot center dot pi(quinoline) interactions are strong, but are much weaker in molecule A of (5: X-2 = 2,3-Cl-2) and (5: X-2 = 2,4-Cl-2).