N. S. Karthikeyan

(3E,5E)-1-Benzyl-3,5-bis­(2-fluoro­benzyl­idene)piperidin-4-one

The inversion-related molecules of the title compound, C26H21F2NO, associate into closed dimeric subunits via co-operative C—H⋯π interactions. Two non-classical C—H⋯O and one C—H⋯N intramolecular hydrogen bonds are also found in the crystal structure. The piperidin-4-one ring adopts a sofa conforamtion with the 1-benzyl group in the equatorial position, and the equiplanar fluorophenyl substituents in the 3- and 5-positions stretched out on either side. The 1-benzyl group is disposed towards the substituent in the 6th position of the piperidin-4-one ring. The 3,5-diene units possess E configurations.

(3E,5E)-1-Benzyl-3,5-dibenzyl­idenepiperidin-4-one

In the title compound, C26H23NO, C—H⋯O hydrogen bonds generate a ribbon structure along the a axis. These ribbons further assemble into a one-dimensional sheet parallel to the ac plane via C—H⋯π interactions. The piperidin-4-one ring adopts a sofa conformation with the 1-benzyl group in the equatorial position, and the 3- and 5-phenyl substituents stretched out on either side. The benzylidene units adopt E configurations and the 1-benzyl group is disposed towards the 3- substituent of the piperidin-4-one ring.

(3E,5E)-3,5-Bis(4-allyl­oxybenzyl­idene)-1-benzyl­piperidin-4-one

In the title compound C32H31NO3, the allyloxy groups on either side of the piperidin-4-one ring are conformationally disordered. The contribution of major and minor components of the allyloxy group at the 3rd position of the ring are 0.576 (4) and 0.424 (4), respectively, and those at the 5th position are 0.885 (3) and 0.115 (3), respectively. The six-membered piperidin-4-one ring adopts a sofa conformation with the benzyl group occupying an equatorial position and the olefinic double bonds possessing an E configuration. Flanking phenyl substituents are stretched out on either side of the six-membered ring. π–π interactions with a centroid–centroid distance of 3.885 (1) Å give rise to molecular dimers and short C—H⋯π contacts lead to chains along the c axis.

3-(7,8,13,14-Tetra-hydrodi-benzo-[a,i]phen-an-thridin-5-yl)benzene-1,2-diol.

In the title compound, C27H21NO2, the half-chair conformation of the alicyclic rings gives rise to a slightly folded structure of the central tricyclic tetrahydrophenanthridine unit. Tandem intramolecular O—H⋯N and O—H⋯O hydrogen bonds give rise to adjacent S(6) and S(5) rings, respectively, which dictate the conformation of the 5-aryl substituent. In the crystal structure, an intermolecular C—H⋯O contact generates chains parallel to [101]. Short O—H⋯π and C—H⋯π contacts are also observed.

(7E)-5-Benzyl-7-(2-chloro-benzyl-idene)-3-(2-chloro-phen-yl)-2-phenyl-3,3a,4,5,6,7-hexa-hydro-2H-pyrazolo-[4,3-c]pyridine.

In the title 2H-pyrazolo[4,3-c]pyridine derivative, C32H27Cl2N3, the dihydropyrazole ring adopts an envelope conformation and the piperidine fused ring a twisted-chair conformation. Two short intramolecular C—H⋯Cl contacts are observed. The crystal packing is characterized by dimeric C—Cl⋯π interactions involving the 5-benzyl ring, with Cl⋯centroid and closest atomic Cl⋯π distances of 3.778 (2) and 3.366 (4) Å, respectively.