Crystal structures of (±)-(1SR,5SR,6SR,7SR,10SR,11SR,13RS,14SR)-13-hy­droxy-7-meth­oxy­meth­oxy-11,15,18,18-tetra­methyl-3-oxo-2,4-dioxa­tetra­cyclo­[12.3.1.01,5.06,11]octa­dec-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).