1-Butylquinine tetrafluoroborate

In the title salt (2S,4S,8R)-1-butyl-2-[(R)-(hydroxy)(6-methoxyquinolin-4-yl)methyl]-8-vinylquinuclidin-1-ium tetrafluoroborate, C24H33N2O2 +·BF4 −, the butyl substituent at the 1-position is in an equatorial conformation with respect to the unsubstituted six-membered ring and the four butyl C atoms are almost coplanar with the ring N and vinyl C atoms (r.m.s. deviation = 0.046 Å). In the crystal, the cations are linked by O—H⋯N hydrogen bonds. The F atoms of the tetrafluoroborate group are disordered over two sets of site with an occupancy raitio of 0.552 (8):0.448 (8).


Comment
The overall utility of asymmetric catalysts can be compared by examining three main criteria: 1) the variety of reactions that the catalyst can promote, 2) the availability of both enantiomeric antipodes of the catalyst at a reasonable price, and 3) the stability of the catalyst. Alkaloids and quaternary ammonium salt fulfill all of these criteria. They make them one of the most useful catalysts to date. Alkaloids can be transformed to quaternary ammonium salt in one or two steps. Chiral 1-butylquinine cation was reacted with BF 4 leading to a new salt. The latter could serve as a chiral catalyst for different asymmetric reactions.
The X-ray structure shows that the boron atom presents statistically two types of tetrahedral environments: E1 and E2 with occupancy rates of 55.2% and 44.8%, respectively. The first environment (E1), which consists of F1A, F2A, F3A and F4, is strongly distorted as indicated by the B-F bond lengths varying from 1.324 (5) Bruno et al., 2004). It commonly adopts the open conformation III described in solution by Dijkstra et al.,1989, and in which the butyl-substituted quinuclidine nitrogen, N1, turns away from the quinoline ring and is oriented in the same direction as the methoxy oxygen. The torsion angles, which best characterized the overall shape, C12-C11-C10-O1 and, O1-C10 -C1-C2, are -22.6 (4)° and 45.8 (3)°, respectively. The butyl substituent at N1 is in equatorial conformation with respect to the six-membered ring C3/C7-N1 and the four butyl atoms are almost coplanar with N1-C20/C23 (r.m.s. deviation of 0.046 Å), and parallel to the [001] direction.
In the crystal structure, molecules are mainly linked by intermolecular O-H···N hydrogen bonds into helical chains running along a crystallographic 2 1 axis at y=1/4 position in the a-axis direction with graph-set notation C(7) (Bernstein et al. (1994). The stability of the chains also benefits from the tilted superimposition of adjacent quinolin moieties with dihedral angle of 36.2 (4)° and shortest centroid distance of 4.162 (5) Å.
The reaction mixture was stirred for a further 24 h. The mixture was then extracted with CH 2 Cl 2 and the organic phase supplementary materials sup-2 was dried over MgSO 4 . The solvent evaporation method was used to grow [BQ]BF 4 crystals in dichloromethane at room temperature. The product is a colorless single-crystal which is air stable (m.p.197-199 °C).

Refinement
All H atoms attached to C or O atoms were placed in calculated positions (C-H = 0.95-1.00 Å; O-H = 0.84 Å (hydroxyl)) and allowed to ride on their parent atoms, with U iso (H) = 1.2U eq (C aromatic or vinyl ) or U iso (H) =1.5U eq (C others , O). 3007 Friedel opposites were merged    Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger. Symmetry codes: (i) x−1/2, −y+1/2, −z.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
supplementary materials sup-9