Crystal structures of three 4-[3-(XC6H4)-hexahydro[1,3] oxazolo[3,4-a]pyridin-1-yl]-2,8-bis(trifluoromethyl)quinolines (X = 3-MeO, 4-MeO and 4-HO)

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The crystal structures of three racemic 4-{3- (X-phenyl)hexahydro[1,3]oxazolo[3,4-a]pyridin-1-yl}-2,8- bis (trifluoromethyl)quinolines, 2, namely (2: X = 3-MeO, 4-MeO and 4-HO), prepared from mefloquine and XC 6 H 5 CHO, are reported. All three molecules were previously reported to be active in in-vitro studies against the multidrug-resistant tuberculosis strain T113. In each of the three molecules, the piperidinyl ring has a chair shape with substituents in equatorial sites and the 1,3-oxazolidinyl ring exhibit deviations from planarity. All molecules have “F’’ shape conformations with the X-phenyl and quinoline rings lying on one side of the best plane through the fused oxazolidine-piperidine rings, and in an arrangement approaching open butterfly wings. However there are differences in the inter-planar angles. No correlation was established between the anti-TB activity and the molecular conformation. Compound (2: X = 4-MeO) has a onedimensional structure generated from C-F ... π(pyridine) and C-H ... π(methoxyphenyl) interactions. Both (2: X = 3-MeO) and (2: X = 4-HO) have three dimensional structures. The supramolecular arrangements in (2: X = 3-MeO) are derived from C-H ... O(oxazolidine), C-H ... F and C-H ... π(phenyl of quinoline) interactions and those for (2: X = 4-HO) from O-H ... N(piperidine), C-H ... O(hydroxyl), C-H ... F, C-H ... π(phenyl of quinoline), C-F ... π(pyridine), C-F ... π(imine) and p(methoxyphenyl) ... π(methoxyphenyl) interactions.