rac-5-Bromo-N-benzylisatincreatinine ethanol monosolvate

In the title compound [systematic name: rac-1-benzyl-5-bromo-3-hydroxy-3-(2-imino-3-methyl-5-oxoimidazolidin-4-yl)-2,3-dihydro-1H-indol-2-one ethanol monosolvate], C19H17BrN4O3·C2H5OH, which crystallized as a racemate (RR and SS), the isatin ring is almost planar, with an r.m.s. deviations from the mean plane of 0.0276 (14) Å. The phenyl ring of the benzyl group makes a dihedral angle with the mean plane of the isatin ring of 87.40 (5)° and the dihedral angle between the imidazole and isatin rings is 58.56 (7)°. In the crystal, molecules are linked into two-dimensional pleated-sheet networks in the ac plane formed by O—H⋯O, N—H⋯O and O—H⋯N hydrogen bonds; within these sheets there are R 4 4(10) rings that involve three molecules of the title compound and a single ethanol solvent molecule. In addition, there are π–π interactions between inversion-related benzyl groups, with an interplanar spacing of 3.444 (3) Å.


Related literature
Background information on the biological importance of isatins has been given by Pandeya et al. (2005), and by Vine et al. (2007). For similar structures, see: Tang  H atoms treated by a mixture of independent and constrained refinement Á max = 1.19 e Å À3 Á min = À0.45 e Å À3 Table 1 Hydrogen-bond geometry (Å , ). In view of the biological importance of isatins (Pandeya et al., 2005;Vine et al., 2007) we have synthesized a series of novel compounds containing isatin and creatinine moieties to screen for their anticancer activity. The title compound was prepared by the aldol condensation of 5-bromo-N-benzylindol-2,3-dione (5-bromo-N-benzylisatin) with 2-amino-1methyl-1H-imidazol-4(5H)-one (creatinine) in the presence of sodium acetate in acetic acid. Earlier, we reported on the crystal structure of isatin creatinine analogs containing N-methyl and N-phenyl substitituents (Penthala et al., 2009a,b).
To obtain detailed information on the structural conformations of the molecules for analysis of structure-activity relationships (SAR), we determined the X-ray crystal structure of the title compound. The compound crystallized as a racemate (RR and SS). The molecular structure of title compound is shown in Fig. 1

Experimental
The title compound was prepared according to a previously reported procedure (Penthala et al., 2009a,b).
The largest difference map peak (~1.2 e Å 3 ) is about 1.87 Å away from C7, and so could conceivably represent a very minor impurity in which the Br atom is attached to C7 rather than C5. Such a disorder model was made, and it refined in a stable manner with a refined occupancy of <2%. Although the difference map was flatter and it had very good 'quality′ statistics, there seemed little point in keeping this disorder model because the occupancy was so low.

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-value wR and goodness of fit S are based on F 2 . Conventional R-values 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 R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-values based on F 2 are statistically about twice as large as those based on F, and R-values based on ALL data will be even larger.