Crystal structures of two polymorphs of tixocortol pivalate

Abstract

Two polymorphs, (I) and (II), of (S)-{2-[(8S,9S,10R,11S,13S,14S,17R)-11,17-dihy-droxy-10,13-dimethyl-3-oxo-2,6,7,8,9,11,12,14,15,16-deca-hydro-1H-cyclo-penta-[a]phenanthren-17-yl]-2-oxoeth-yl} 2,2-di-methyl-propane-thio-ate, C₂₆H₃₈O₅S, have been identified. They are ortho-rhom-bic, non-centrosymmetric (P2₁2₁2₁). The structures display layers of mol-ecules conected via O-H⋯O hydrogen bonds along the b-axis direction in polymorph (I) and along the c-axis direction in polymorph (II). The structure of (II) exhibits disorder of the main mol-ecule.

Keywords: crystal structure; pivalone; polymorphs; tixocortol.

Figure 1

ORTEP view of polymorph (I). Displacement ellipsoids are drawn at the 50% probability level.

Figure 2

ORTEP view of polymorph (II). Displacement ellipsoids are drawn at the 30% probability level. The minor component of the disorder is omitted for clarity.

Figure 3

View of the hydrogen bond-network in polymorph (I).

Figure 4

View of the hydrogen-bond network in polymorph (II).

Figure 5

View of the crystal morphology of polymorph (I) (top) and (II) (bottom).

Figure 6

Reaction scheme for the synthesis of tixocortol pivalate.

Figure 7

PXRD patterns of polymorphs (I) and (II) and their simulated patterns from the SCXRD study at room temperature.