title: Long-chain 2H-azirines with heterogeneous terminal halogenation from the marine sponge Dysidea fragilis.
abstract: Three new omega-halogenated long-chain 2H-azirines were isolated from the sponge Dysidea fragilis. Their structures revealed heterogeneity in both the composition of the terminal 1,1-dihalo-vinyl group and enantiomeric ratios at C2 of the azirine-2-carboxylate ester terminus. Azirine-2-carboxylate esters were shown to racemize spontaneously. A hypothesis is proposed for the biosynthesis of the azirinecarboxylate family of natural products that involves enzyme-catalyzed free radical halogenation followed by elimination of hydrohalic acid.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, San Diego, MC0358, 9500 Gilman Drive, La Jolla, CA 92093, USA.
authors.forename: Colin K
authors.initials: CK
authors.lastname: Skepper
authors.forename: Tadeusz F
authors.initials: TF
authors.lastname: Molinski
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001389:Azirines / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D001685:Biological Factors / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D045744:Cell Line, Tumor; D004354:Drug Screening Assays, Antitumor; D047088:Dysidea / Q000737:chemistry*; D054879:Halogenation; D006801:Humans; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D001389:Azirines; D001685:Biological Factors; C096952:dysidazirine; C096953:antazirine