tert-Butyl 2-{[2,8-bis(trifluoromethyl)quinolin-4-yl](hydroxy)methyl}piperidine-1-carboxylate

The title molecule, C22H24F6N2O3, adopts a folded conformation whereby the carboxylate residue lies over the quinolinyl residue, with the dihedral angle between the carbamate and quinoline planes being 41.64 (7)°. Helical supramolecular C(7) chains sustained by O—H⋯O hydrogen bonds propagating along the a-axis direction feature in the crystal packing. The F atoms of one of the CF3 groups are disordered over two orientations; the major component has a site occupancy of 0.824 (7).

The title molecule, C 22 H 24 F 6 N 2 O 3 , adopts a folded conformation whereby the carboxylate residue lies over the quinolinyl residue, with the dihedral angle between the carbamate and quinoline planes being 41.64 (7) . Helical supramolecular C(7) chains sustained by O-HÁ Á ÁO hydrogen bonds propagating along the a-axis direction feature in the crystal packing. The F atoms of one of the CF 3 groups are disordered over two orientations; the major component has a site occupancy of 0.824 (7).

Data collection
The use of the EPSRC X-ray crystallographic service at the University of Southampton, England and the valuable assistance of the staff there is gratefully acknowledged. JLW acknowledges support from CAPES and FAPEMIG (Brazil).
In the molecule of (I), Fig. 1, the hydroxyl group lies to one side of the plane through the quinolinyl residue and the substituted piperidine ring to other with the carboxylate ester folded over to lie over the quinolinyl plane. However, the two residues are non-parallel with the dihedral angle between the quinolinyl and carbamate planes being 41.64 (7) °. The piperidine ring has a conformation close to a chair form. Mefloquine used as a reagent was a racemate. However, the reported crystal structure is of one form of a racemic mixture as the molecules spontaneously resolved during crystallization. The sum of the angles at the site of substitution, the trisubstituted N2 atom, is 360° indicating a planar geometry, and hence an achiral centre. In (I), the configurations at the C12 and C13 positions are R and S, respectively. The most prominent intermolecular interactions in the crystal structure are O-H···O hydrogen bonds that lead to helical supramolecular chains along the a axis, Fig. 1 and Table 1.

Experimental
The compound was prepared by a published procedure (Grellepois et al., 2005) from Boc 2 O and mefloquine in the presence of Et 3 N. Colourless chips of (I) were grown from an EtOH solution, M.pt. 419-420 K.
The O-H H atom was located in a difference and refined with O-H = 0.84±0.01 Å, and with U iso (H) = 1.5U eq (O). One of the CF 3 groups was found to be disordered. This was resolved over two positions for each F atom. The pairs of F atom had common anisotropic displacement parameters. The major component of the disordered F atoms had a site occupancy = 0.824 (7).
supplementary materials sup-2 Figures Fig. 1. The molecular structure of (I) showing displacement ellipsoids at the 50% probability level.