5-Fluoro-N-(2-methyl-3-oxo-1-thia-4-azaspiro[4.5]dec-4-yl)-3-phenyl-1H-indole-2-carboxamide

In the title compound, C24H24FN3O2S, the 1,3-thiazolidine ring adopts an envelope conformation with the S atom as the flap, while the cyclohexane ring is in a chair conformation. In the crystal, molecules are linked by N—H⋯O and C—H⋯F hydrogen bonds, forming a three-dimensional network. The unit cell contains six voids of 57 Å3, but the residual electron density (highest peak = 0.23 e Å−3 and deepest hole = −0.19 e Å−3) in the difference Fourier map suggests no solvent molecule occupies this void.

In the title compound, C 24 H 24 FN 3 O 2 S, the 1,3-thiazolidine ring adopts an envelope conformation with the S atom as the flap, while the cyclohexane ring is in a chair conformation. In the crystal, molecules are linked by N-HÁ Á ÁO and C-HÁ Á ÁF hydrogen bonds, forming a three-dimensional network. The unit cell contains six voids of 57 Å 3 , but the residual electron density (highest peak = 0.23 e Å À3 and deepest hole = À0.19 e Å À3 ) in the difference Fourier map suggests no solvent molecule occupies this void.   Table 1 Hydrogen-bond geometry (Å , ).
In the crystal structure, N-H···O and C-H···F hydrogen bonds connect the adjacent molecules to each other, forming a three dimensional network. In addtion, π-π and C-H···π interactions are not observed.

Experimental
A mixture of 5-fluoro-3-phenyl-1H-indole-2-carbohydrazide (0.0025 mol), cyclohexanone (0.003 mol) and 2mercaptopropionic acid (0.01 mol) was refluxed in 20 ml dry benzene for 5 h using a Dean-Stark water separator. Excess benzene was evaporated in vacuo. The resulting residue was triturated with saturated NaHCO 3 solution until CO 2 evolution ceased and was refrigerated overnight. The solid thus obtained was washed with water, filtered, dried, and  Refinement H atoms bonded to C atoms were positioned geometrically with C-H = 0.93 -0.98 Å, and refined using a riding model with U iso (H) = 1.2 or 1.5U eq (C). The H atoms of the two amide groups were found in a difference Fourier map, restrained with N-H = 0.86 (2) Å and refined with U iso = 1.2U eq (N). The unit cell contains six voids of 57 Å 3 , but the residual electron density (highest peak = 0.23 e.Å -3 and deepest hole = -0.19 e.Å -3 ) in the difference Fourier map suggests no solvent molecule occupies this void.

Figure 1
The structure of the title molecule with the atom labelling scheme. Displacement ellipsoids for non-H atoms are drawn at the 30% probability level.

Special details
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles Refinement. Refinement on F 2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses 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 observed criterion of F 2 > σ(F 2 ) is used only for calculating -R-factor-obs 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.