title: Divergent synthesis and chemical reactivity of bicyclic lactone fragments of complex rearranged spongian diterpenes.
abstract: The synthesis and direct comparison of the chemical reactivity of the two highly oxidized bicyclic lactone fragments found in rearranged spongian diterpenes (8-substituted 6-acetoxy-2,7-dioxabicyclo[3.2.1]octan-3-one and 6-substituted 7-acetoxy-2,8-dioxabicyclo[3.3.0]octan-3-one) are reported. Details of the first synthesis of the 6-acetoxy-2,7-dioxabicyclo[3.2.1]octan-3-one ring system, including an examination of several possibilities for the key bridging cyclization reaction, are described. In addition, the first synthesis of 7-acetoxy-2,8-dioxabicyclo[3.3.0]octanones containing quaternary carbon substituents at C6 is disclosed. Aspects of the chemical reactivity and Golgi-modifying properties of these bicyclic lactone analogs of rearranged spongian diterpenes are also reported. Under both acidic and basic conditions, 8-substituted 2,7-dioxabicyclo[3.2.1]octanones are converted to 6-substituted-2,8-dioxabicyclo[3.3.0]octanones. Moreover, these dioxabicyclic lactones react with primary amines and lysine side chains of lysozyme to form substituted pyrroles, a conjugation that could be responsible for the unique biological properties of these compounds. These studies demonstrate that acetoxylation adjacent to the lactone carbonyl group, in either the bridged or fused series, is required to produce fragmented Golgi membranes in the pericentriolar region that is characteristic of macfarlandin E.
authors: Department of Chemistry, University of California, Irvine, California 92697-2025, USA.
authors: Martin J
authors: MJ
authors: Schnermann
authors: Christopher M
authors: CM
authors: Beaudry
authors: Nathan E
authors: NE
authors: Genung
authors: Stephen M
authors: SM
authors: Canham
authors: Nicholas L
authors: NL
authors: Untiedt
authors: Breanne D W
authors: BD
authors: Karanikolas
authors: Christine
authors: C
authors: Sütterlin
authors: Larry E
authors: LE
authors: Overman
mesh_terms: D000818:Animals; D001643:Bridged Bicyclo Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D004224:Diterpenes / Q000737:chemistry*; D007783:Lactones / Q000138:chemical synthesis* / Q000737:chemistry*; D008968:Molecular Conformation; D011161:Porifera / Q000737:chemistry*; D051381:Rats; D013237:Stereoisomerism
chemical_list: D001643:Bridged Bicyclo Compounds; D004224:Diterpenes; D007783:Lactones