Ethyl 2-[2-(2,4-diphenyl-3-azabicyclo[3.3.1]nonan-9-ylidene)hydrazin-1-yl]-4-methyl-1,3-thiazole-5-carboxylate dimethylformamide monosolvate

In the title molecule, C27H30N4O2S·C3H7NO, the fused piperidine and cyclohexane rings adopt a twin chair conformation and the phenyl groups occupy equatorial sites. The phenyl rings make a dihedral angle of 40.74 (2)°. In the crystal, the dimethylformamide solvent molecule is connected to the main molecule by an N—H⋯O hydrogen bond. An additional N—H⋯O hydrogen bond connects molecules into chains along [100]. Pairs of weak C—H⋯O hydrogen bonds connect inversion-related chains. The ethyl group was refined as disordered over two sets of sites with an occupancy ratio of 0.660 (17):0.340 (17).

In the title molecule, C 27 H 30 N 4 O 2 SÁC 3 H 7 NO, the fused piperidine and cyclohexane rings adopt a twin chair conformation and the phenyl groups occupy equatorial sites. The phenyl rings make a dihedral angle of 40.74 (2) . In the crystal, the dimethylformamide solvent molecule is connected to the main molecule by an N-HÁ Á ÁO hydrogen bond. An additional N-HÁ Á ÁO hydrogen bond connects molecules into chains along [100]. Pairs of weak C-HÁ Á ÁO hydrogen bonds connect inversion-related chains. The ethyl group was refined as disordered over two sets of sites with an occupancy ratio of 0.660 (17):0.340 (17).

Comment
Thiazoles are an interesting unit in medicinal chemistry and are responsible for numerous pharmacological and biological properties (Hutchinson et al. 2002;Bondock et al., 2007;Ramachandran et al., 2009). This has piqued our interest in the synthesis of thiazole containing compounds. The importance of bicyclic compounds as intermediates in the synthesis of a several physiologically active compounds have been reviewed by Jeyaraman & Avila (1981). Moreover, these bridged bicyclic compounds exhibit twin chair, chair-boat or twin boat conformations and possess interesting stereochemistries.
In order to investigate the change in molecular conformation of the piperidine and cyclohexane rings, the X-ray structure determination of the title compound was carried out. The six-membered heterocyclic piperidine ring ( Fig. 1)

Experimental
To a boiling solution of the bicyclic thiosemicarbazone (0.01 mol) in ethanolic-chloroform (1:1 / v:v), ethyl-2-chloroacetoacetate(0.01 mol), sodium acetate trihydrate (0.02 mol) and a few drops of acetic acid were added and refluxed for about 5-6 h. After the completion of reaction, excess of solvent was removed under reduced pressure and poured into water. After work-up, the solid was separated and purified by column chromatography using benzene-ethyl acetate (9:1 / v:v) as eluent on neutral alumina. Colourless crystals were grown by slow evaporation method using dimethylformamide as the solvent.

Refinement
H atoms bonded to C atoms were included in calculated positions with C-H = 0.93-0.98Å and included in the refinement with U iso (H) = 1.2U eq (C) or 1.5U eq (C methyl ). H atoms bonded to N atoms were refined independently with isotropic displacment parameters.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ.