[(2S,5R)-1-Methyl-5-phenylpyrrolidin-2-yl]diphenylmethanol

In the title compound, C24H25NO, the phenyl and diphenylmethanol substituents are syn to each other. The pyrrolidine ring has an envelope conformation with the flap atom being the C atom bearing the phenyl substituent. The hydroxy group forms an intramolecular hydrogen bond with the pyrrolidine N atom, and the phenyl rings lie to same side of the molecule. The crystal packing features C—H⋯π interactions. Two slightly displaced co-planar orientations were found for one of the phenyl rings; the major component had a site-occupancy factor of 0.782 (15).

In the title compound, C 24 H 25 NO, the phenyl and diphenylmethanol substituents are syn to each other. The pyrrolidine ring has an envelope conformation with the flap atom being the C atom bearing the phenyl substituent. The hydroxy group forms an intramolecular hydrogen bond with the pyrrolidine N atom, and the phenyl rings lie to same side of the molecule. The crystal packing features C-HÁ Á Á interactions. Two slightly displaced co-planar orientations were found for one of the phenyl rings; the major component had a site-occupancy factor of 0.782 (15).  Table 1 Hydrogen-bond geometry (Å , ).

Related literature
Cg is the centroid of the C6-C11 ring.  (Walsh & Kozlowski, 2008). One asymmetric reaction where chiral β-amino alcohol ligands have found enormous success is the enantioselective addition of organozinc reagents to carbonyl compounds, with particular emphasis in the alkylation of aldehydes by the addition of diethylzinc. A more challenging reaction is the asymmetric arylation reaction, since arylzinc reagents are more reactive than the dialkylzinc and the ligand turnover has to highly efficient in order to circumvent the uncatalyzed background reaction (Paixão et al., 2008).

D-HÁ
Considering the proline motif as a privileged framework for the development of asymmetric catalysts (Yoon & Jacobsen, 2003) we have recently described a new chiral ligand for the highly enantioselective addition of arylzinc reagents to aldehydes. The ligands were prepared by an straightforward synthetic sequence, with a Heck reaction of arenediazonium salts (Heck-Matsuda reaction) as the key step (Taylor et al., 2011). Herein, we describe the crystal structure analysis of a representative molecule, the title compound, (I).
The crystal structure analysis of (I) confirms the structure as having the expected syn relationship between the phenyl and the diphenylmethanol substituents, Fig. 1 (Moro et al., 2010;Shabbir et al., 2009). The pyrrolidine ring is in an envelope conformation with C1 out of the plane formed by the other four atoms, the ring puckering parameters being: q 2 = 0.379 (2)° and φ 2 = 32.0 (3) ° (Cremer & Pople, 1975). The hydroxy group is orientated over the five-membered ring to facilitate the formation of an intramolecular O-H···N hydrogen bond, Table 1. The crystal packing is dominated by C-H···π interactions, Table 1. Globally. the pyrrolidine pack in the ab plane and are sandwiched by benzene rings along the c direction, Fig. 2.

Refinement
All H-atoms were placed in calculated positions (O-H = 0.84 Å, and C-H 0.95 to 1.00 Å) and were included in the refinement in the riding model approximation with U iso (H) = 1.2U eq (C) and 1.5U eq (O; methyl-C). In the absence of significant anomalous scattering effects, 1707 Friedel pairs were averaged in the final refinement. The 2S,5R designation was chosen based on the synthesis (Moro et al., 2010). The C7-C12 benzene ring was found to be disordered with one orientation slightly displaced with respect to the second, co-planar, orientation. In the final refinement, matching C atoms were constrained to have the same anisotropic displacement parameter. The major component of the disordered residue had a site occupancy factor = 0.782 (15). Fig. 1. The molecular structure of compound (I) showing the atom-labelling scheme and displacement ellipsoids at the 35% probability level. Only the major component of the disordered benzene ring is illustrated.

Special details
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The 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 > 2σ(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.