Redetermnation of lagochiline monohydrate

In the title compound, C20H36O5·H2O, previously studied by film methods [Vorontsova et al. (1975 ▶). Izvest. USSR Ser. Chem. 2, 338–343], the H atoms have been located and the absolute structure (seven stereogenic centres) established. An intramolecular O—H⋯O hydrogen bond generates an S(6) ring. In the crystal, molecules are linked by O—H⋯O hydrogen bonds, forming a three-dimensional network.

The value of the Flack parameters 0.2 (2) (Flack, 1983) allows to establish the absolute configuration of the asymmetric  (Table). Four hydroxyl groups of the molecule ( Fig.1), showing protonodonor as well protonoacceptor properties, are involved in the formation of the complicated system of the intermolecular H-bonds in the crystalline state (Table). The water molecule is H-bonded to three molecules of

Experimental
The extracting of the lagochiline was preformed according to the method in Abramov et al. (1958). Colourless needles of (I) were grown by slow evaporation of a solution in acetone.

Refinement
H-atoms bonded to carbon were positioned geometrically and refined using a riding model, with U iso (H)=1.2 or 1.5 times U eq (C). The positions of the hydrogen atoms at the hydroxyl groups of the lagochiline molecule and water have been gained from the difference Fourier map

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.