title: Crystal structures of (±)-(1SR,5SR,6SR,7SR,10SR,11SR,13RS,14SR)-13-hy-droxy-7-meth-oxy-meth-oxy-11,15,18,18-tetra-methyl-3-oxo-2,4-dioxa-tetra-cyclo-[12.3.1.0(1,5).0(6,11)]octa-dec-15-en-10-yl benzoate, its 13-epimer and 13-one derivative.
abstract: The title compounds, C29H38O8·0.25C5H12, (A), C29H38O8, (B), and C29H36O8, (C), are tetra-cyclic 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 mol-ecules (A and A') and a half mol-ecule of solvent pentane disordered about an inversion center. The mol-ecular conformations of (A), (B) and (C) are similar except for the flexible meth-oxy-meth-oxy group. The cyclo-hexane, cyclo-hexene and central cyclo-octane 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), inter-molecular O-H⋯O, C-H⋯O and C-H⋯π inter-actions link the independent benzoates alternately, forming a chain structure. In the crystals of (B) and (C), mol-ecules are linked through O-H⋯O and C-H⋯π inter-actions, and C-H⋯O hydrogen bonds, respectively, into similar chains. Further, weak inter-molecular C-H⋯O inter-actions connect the chains into a three-dimensional network in (A) and a sheet in (B), whereas no other interactions are observed for (C).
authors.affiliation: School of Medicine, Keio University, Hiyoshi 4-1-1, Kohoku-ku, Yokohama 223-8521, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Oishi
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Technology, Keio University, Hiyoshi 3-14-1, Kohoku-ku, Yokohama 223-8522, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Fukaya
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Technology, Keio University, Hiyoshi 3-14-1, Kohoku-ku, Yokohama 223-8522, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Yamaguchi
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Technology, Keio University, Hiyoshi 3-14-1, Kohoku-ku, Yokohama 223-8522, Japan.
authors.forename: Tomoya
authors.initials: T
authors.lastname: Sugai
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Technology, Keio University, Hiyoshi 3-14-1, Kohoku-ku, Yokohama 223-8522, Japan.
authors.forename: Ami
authors.initials: A
authors.lastname: Watanabe
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Technology, Keio University, Hiyoshi 3-14-1, Kohoku-ku, Yokohama 223-8522, Japan.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Sato
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Technology, Keio University, Hiyoshi 3-14-1, Kohoku-ku, Yokohama 223-8522, Japan.
authors.forename: Noritaka
authors.initials: N
authors.lastname: Chida
keywords: crystal structure; hydrogen bonds; paclitaxel; taxane skeleton