Crystal structures of (±)-(1SR5SR6SR7SR10SR11SR13RS14SR)-13-hy­droxy-7-meth­oxy­meth­oxy-11151818-tetra­methyl-3-oxo-24-dioxa­tetra­cyclo­12.3.1.015.0611octa­dec-15-en-10-yl benzoate its 13-epimer and 13-one derivative

摘要

The title compounds, C29H38O8·0.25C5H12, (>A), C29H38O8, (>B), and C29H36O8, (>C), are tetra­cyclic benzoates possessing a taxane skeleton with a fused dioxolane ring as the core structure. In the asymmetric unit of (>A), there are two independent benzoate mol­ecules (A and A′) and a half mol­ecule of solvent pentane disordered about an inversion center. The mol­ecular conformations of (>A), (>B) and (>C) are similar except for the flexible meth­oxy­meth­oxy group. The cyclo­hexane, cyclo­hexene and central cyclo­octane rings adopt chair, half-chair and chair–chair (extended crown) forms, respectively. The dioxolane rings are essentially planar, while the dioxolane ring of A′ is slightly twisted from the mean plane. In the crystal of (>A), inter­molecular O—H⋯O, C—H⋯O and C—H⋯π inter­actions link the independent benzoates alternately, forming a chain structure. In the crystals of (>B) and (>C), mol­ecules are linked through O—H⋯O and C—H⋯π inter­actions, and C—H⋯O hydrogen bonds, respectively, into similar chains. Further, weak inter­molecular C—H⋯O inter­actions connect the chains into a three-dimensional network in (>A) and a sheet in (>B), whereas no other interactions are observed for (>C).