2-Hydroxy-16-[(E)-4-hydroxy-3-methoxybenzylidene]-13-(4-hydroxy-3-methoxyphenyl)-11-methyl-1,11-diazapentacyclo[12.3.1.02,10.03,8.010,14]octadeca-3(8),4,6-triene-9,15-dione

In the title compound, C32H30N2O7, the piperidone ring adopts a chair conformation and the five-membered ring of the dihydroindenone ring system adopts an envelope conformation. Intramolecular O—H⋯N and C—H⋯O hydrogen bonds occur. The dihedral angle between the two hydroxy-subsituted methoxyphenyl rings is 71.12 (5)°. In the crystal structure, molecules are connected by intermolecular O—H⋯O hydrogen bonds, forming layers parallel to (001). These layers are further connected by C—H⋯O hydrogen bonds, forming a three-dimensional network.

In the title compound, C 32 H 30 N 2 O 7 , the piperidone ring adopts a chair conformation and the five-membered ring of the dihydroindenone ring system adopts an envelope conformation. Intramolecular O-HÁ Á ÁN and C-HÁ Á ÁO hydrogen bonds occur. The dihedral angle between the two hydroxysubsituted methoxyphenyl rings is 71.12 (5) . In the crystal structure, molecules are connected by intermolecular O-HÁ Á ÁO hydrogen bonds, forming layers parallel to (001). These layers are further connected by C-HÁ Á ÁO hydrogen bonds, forming a three-dimensional network.
Pyrrolidines are important building blocks in organic synthesis, and in the past years have emerged as privileged organocatalysts (Dalko & Moisan, 2004;Seayad & List, 2005). Compounds containing the piperidine subunit act as excellent inhibitors of p38 activity and TNF-α release (Natarajan et al., 2006) and consequently, the efficient preparation of these heterocycles has received significant attention.

Refinement
Atoms H1O2, H1O5 and H1O7 were located in a difference Fourier map and refined freely. The remaining H atoms were positioned geometrically (C-H = 0.93-0.98 Å) and were refined using a riding model, with U iso (H) = 1.2 or 1.5U eq (C). A rotating group model was applied to the methyl groups. Fig. 1. The asymmetric unit of the title compound, showing 30% probability displacement ellipsoids and the atom-numbering scheme (H atoms are omitted for clarity).

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.
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.