(1R,4R,5R)-1,3,4-Triphenyl-7-[(R)-1-phenylethyl]-2-oxa-3,7-diazaspiro[4.5]decan-10-one

In the title compound, C33H32N2O2, the polysubstituted piperidine ring adopts a chair conformation. The isoxazolidine ring is in an envelope conformation. In the crystal structure, intra- and intermolecular C—H⋯π interactions involving the phenyl rings are observed.

In the title compound, C 33 H 32 N 2 O 2 , the polysubstituted piperidine ring adopts a chair conformation. The isoxazolidine ring is in an envelope conformation. In the crystal structure, intra-and intermolecular C-HÁ Á Á interactions involving the phenyl rings are observed. 335 parameters H-atom parameters constrained Á max = 0.16 e Å À3 Á min = À0.14 e Å À3 Table 1 Hydrogen-bond geometry (Å , ).
The molecular structure of (I) is shown in Fig.1. The five-membered isoxazolidine ring has an envelope conformation, as Weak intramolecular C-H···O and C-H···π interactions are observed in the molecular structure. The packing of molecules is governed by weak C-H···π interactions (Table 1) and van der Walls interactions. In the Table 1, Cg1, Cg2 and Cg3 denote the centroids of the C71-C76, C91-C96 and C81-C86 phenyl rings.

Experimental
A mixture of [(R)-1-phenylethyl]-3-[(E)-phenylmethylidene]tetrahydro-4(1H)-pyridinone (0.300 g, 1 mmol) and nitrone (0.244 g, 1.2 mmol) in toluene (25 ml) was refluxed for 10 h. The progress of the reaction was monitored by thin-layer chromatography (TLC) and after completion of the reaction, the solvent was evaporated in vacuo. The residue was then subjected to flash column chromatography on silica gel using petroleum ether-ethyl acetate (10:1) as eluent to obtain crystals of the title compound in 8% yield (0.040 g) along with two other products in semi-solid form.

Refinement
H atoms were placed at calculated positions and allowed to ride on their carrier atoms with C-H = 0.93-0.98 Å, and U iso = 1.2U eq (C) for CH 2 and CH groups, and 1.5U eq for CH 3 groups. In the absence of significant anomalous scattering, the absolute configuration could not be reliably determined and Friedel pairs were merged.
supplementary materials sup-2 Figures Fig. 1. The molecular structure of the title compound, showing 30% probability displacement ellipsoids and the atom-numbering scheme.
Orthorhombic, P2 1 2 1 2 1 Mo Kα radiation λ = 0.71073 Å Hall symbol: P 2ac 2ab Cell parameters from 25 reflections a = 10.589 (5) (2)   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 > 2sigma(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.