Ethyl 4′-ethenyl-2′-oxo-4-phenyl-2-(3,4,5-trimethoxyphenyl)spiro[pyrrolidine-3,3′-indoline]-5-carboxylate monohydrate

In the title compound, C31H32N2O6·H2O, the pyrrolidine ring adopts an envelope conformation. The ethyl C atoms of the ethoxycabonyl group are disordered over two positions with occupancies of ca 0.80 and 0.20. Intramolecular N—H⋯O hydrogen bonds form S(5) and S(6) ring motifs. Molecules are linked into a three-dimensional framework by O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds, and by C—H⋯π interactions.

In the title compound, C 31 H 32 N 2 O 6 ÁH 2 O, the pyrrolidine ring adopts an envelope conformation. The ethyl C atoms of the ethoxycabonyl group are disordered over two positions with occupancies of ca 0.80 and 0.20. Intramolecular N-HÁ Á ÁO hydrogen bonds form S(5) and S(6) ring motifs. Molecules are linked into a three-dimensional framework by O-HÁ Á ÁO, N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds, and by C-HÁ Á Á interactions.

Comment
Substituted pyrrolidine compounds possess antimicrobial and antifungal activity against various pathogens (Amalraj et al., 2003). Several optically active pyrrolidine compounds are used as intermediates in controlled asymmetric synthesis (Suzuki et al., 1994). The spiro-indole-pyrrolidine ring system is a frequently encountered structural motif in many biologically important and pharmacologically relevant alkaloids, e.g. vincrinstine, vinblastine and spirotypostatins (Cordell, 1981). Against this background and to ascertain the detailed information on its molecular conformation, the structure determination of the title compound has been carried out.

Refinement
The ethyl C atoms of the ethoxycarbonyl group are disordered over two positions (C7/C7A and C8/C8A) with refined occupancies of 0.797 (8) and 0.203 (8). The corresponding bond distances involving the disordered atoms were restrained to 1.54 (5) Å, and also the U ij parameters of atoms C7, C7A, C8 and C8A were restrained to an approximate isotropic behaviour.
The O-and N-bound H atoms were located in a difference map and refined with O-H and H···H distances restrained to 0.84 (1) and 1.37 (1) Å, respectively. The remaining H atoms were positioned geometrically (C-H = 0.93-0.98 Å) and allowed to ride on their parent atoms, with U iso (H) = 1.2-1.5(methyl) U eq (C). A search for solvent-accessible voids in the crystal structure using PLATON showed a potential solvent volume of 2189.3 Å 3 and subsequent application of SQUEEZE procedures showed three relevant voids each with a solvent-accessible volume of 730 Å 3 . However, this procedure showed supplementary materials sup-2 no electrons in the voids. This indicates that the crystal lost nearly all of its solvent of crystallization by the time it was used for data collection, without collapse of the structure. Fig. 1. The molecular structure of the title compound, showing 30% probability displacement ellipsoids. Both disorder components are shown. 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 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.

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