(4S,5R)-4-Benzyloxy-5-[4-(cyclohexanecarbonyl)phenyl]-1-(4-methoxybenzyl)pyrrolidin-2-one

The title compound, C32H35NO4, is an unexpected product obtained in the SmI2-mediated radical cross-coupling of a lactam 2-pyridyl sulfone with an arone. The asymmetric unit contains two molecules. In both molecules, the core pyrrolidinone ring adopts an approximate envelope conformation (with the C atom bearling the benzyloxy substituent as the flap) and the cyclohexyl ring has a chair conformation. The relative orientation of the two substitutent groups at the 4- and 5-positions of the pyrrolidinone ring is anti in both molecules, with O(benzyloxy)—C—C—C(benzene) torsion angles of 150.8 (3) and 154.2 (2)°. In the crystal, C—H⋯O interactions involving carbonyl groups as acceptors lead to the formation of a tape motif propagating parallel to the a-axis direction.

The title compound, C 32 H 35 NO 4 , is an unexpected product obtained in the SmI 2 -mediated radical cross-coupling of a lactam 2-pyridyl sulfone with an arone. The asymmetric unit contains two molecules. In both molecules, the core pyrrolidinone ring adopts an approximate envelope conformation (with the C atom bearling the benzyloxy substituent as the flap) and the cyclohexyl ring has a chair conformation. The relative orientation of the two substitutent groups at the 4and 5-positions of the pyrrolidinone ring is anti in both molecules, with O(benzyloxy)-C-C-C(benzene) torsion angles of 150.8 (3) and 154.2 (2) . In the crystal, C-HÁ Á ÁO interactions involving carbonyl groups as acceptors lead to the formation of a tape motif propagating parallel to the a-axis direction.

Experimental
To a solution of (4S)-1-(4-methoxybenzyl)-4-benzyloxy-5-(pyridin-2-ylsulfonyl)pyrrolidin-2-one (0.5 mmol) and benzoylcyclohexane (1.5 mmol) in dry THF (10 ml) was added a freshly prepared t-BuOH-containing SmI 2 (0.1 M in THF, 20 ml, 2.0 mmol) at -60 °C. After being stirred for 2 h, the reaction was quenched with a saturated aqueous solution of NH 4 Cl (10 ml), and the resulting mixture was extracted with EtOAc (3 × 15 ml). The combined organic layers were washed with brine, dried over anhydrous Na 2 SO 4 , filtered and concentrated under reduced pressure. The residue was purified by flash chromatography on silica gel (eluent: EtOAc/Hex = 1: 10) to afford the title compound (white crystals, yield 35%). Single crystals of the tiltle compound were obtained by slow evaporation of a mixture of n-hexane/dichloromethane solution. The title compound was prepared from an optical pure starting material and no racemization was observed in this reaction.

Refinement
The hydrogen atoms were positioned geometrically, with C-H = 0.93, 0.98, 0.97 and 0.96 Å for phenyl, methine, methylene and methyl H atoms, respectively, and were included in the refinement in the riding model approximation. The displacement parameters of methyl H atoms were set to 1.5 U eq (C), while those of other H atoms were set to 1.2 U eq (C).
In the absence of significant anomalous scattering effects, Friedel pairs were merged. The absolute configuration was assigned with reference to the starting materials in the synthetic procedure.  The molecular structure of the title compound showing 50% probability displacement ellipsoids.  The packed unit cell.

(4S,5R)-4-Benzyloxy-5-[4-(cyclohexanecarbonyl)phenyl]-1-(4-methoxybenzyl)pyrrolidin-2-one
Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. 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 R-factors(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.