11-(2-Oxopyrrolidin-1-ylmethyl)-1,2,3,4,5,6,11,11a-octahydropyrido[2,1-b]quinazolin-6-one dihydrate

In the crystal structure of the title compound, C17H21N3O2·2H2O, water molecules are mutually O—H⋯O hydrogen bonded and form infinite chains propagating along the b axis. Neighboring chains are linked by the quinazoline molecules by means of O—H⋯O=C hydrogen bonds, forming a two–dimensional network.

In the crystal structure of the title compound, C 17 H 21 N 3 O 2 Á-2H 2 O, water molecules are mutually O-HÁ Á ÁO hydrogen bonded and form infinite chains propagating along the b axis. Neighboring chains are linked by the quinazoline molecules by means of O-HÁ Á ÁO C hydrogen bonds, forming a twodimensional network.
The molecular structure of the title compound is shown in Figure 2. Quinazoline ring (with exclusion of atom C14) and N-methylolpyrrolidin-2-one ring with inclusion of atom N5 are planar and angle between plans is 77.38 (6)°. Pyrimidine ring takes conformation of sofa leaving the atom C14 from the plane of rest five atoms on 0.409 Å. The third cycle, containing piperidine ring, has conformation of chair.
In the molecule the length of C11═O1 bond (1.241 (2) Å) noticeably, but C2'═O2 bond (1.228 (2) Å) slightly elongated from generally accepted value of C═O bond (Allen et al., 1987). The elongation and planarity of valence bonds of atoms of N10 and N1' indicate conjugation of π-electronic system of carbonic group with not divided electronic pairs of corresponding nitrogen atoms, in case C11═O1 in conjugation participates additionally aromatic ring.
In asymmetric part of crystal cell there are two molecules of water and one molecule of quinazoline derivative ( Figure 2).
Molecules of water are connected by hydrogen bonds Ow1-H···Ow2 and Ow2-H···Ow1 and form the infinite chain along b-axis. These hydrogen bond chains are linked by hydrogen bonds of Ow1-H···O1═C10 and Ow2-H···O2═C2' forming two-dimensional network. Hydrogen bond parameters are shown in Table 1 and packing of molecules with hydrogen bonds are shown on Figure 3. Experimental 0.606 g (3 mmol) of the compound 1 is added to 1.8 ml concentrated sulfuric acid (96%) holding temperature below than 278 K. Then under mixing is added by portion 0.351 g (3 mmol) N-methylolpyrrolidone-2 during 2.5 hours. Reactionary mixture left on night, next day to reaction mixture is added ice and neutralized by ammonia. Precipitate of compound 2 is filtered, washed with water, dried and re-crystallized from hexane, yield 0.9 g (94%).

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