title: Synthesis and bioactivity of the gibberellin, 18-hydroxy-GA1 (GA132).
abstract: As part of a study to confirm putative structural assignments to new gibberellins and to furnish sufficient quantities for biological investigations, a twenty step synthesis of 18-hydroxy GA1 from gibberellic acid (GA3) is described, allowing the confirmation of structure for a new gibberellin, GA132, that occurs in developing grains of barley (Hordeum vulgare). The early part of the sequence involved cleavage of the C(3)-C(4) bond in the A-ring of a 3-oxo intermediate. The ring was then reformed as part of a "domino" process involving the conjugate addition of alkoxide to an alpha-methylene lactone moiety followed by an intramolecular aldol reaction. The bioactivities of the new GA, and its 18-hydroxy-GA4 relative, have been confirmed in dwarf barley growth and alpha-amylase induction assays.
authors.affiliation: Research School of Chemistry, Institute of Advanced Studies, The Australian National University, Canberra, ACT 0200, Australia.
authors.forename: Ellen
authors.initials: E
authors.lastname: Morrison
authors.forename: Peter M
authors.initials: PM
authors.lastname: Chandler
authors.forename: Regan J
authors.initials: RJ
authors.lastname: Thomson
authors.forename: Lewis N
authors.initials: LN
authors.lastname: Mander
mesh_terms: D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D005875:Gibberellins / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D001467:Hordeum / Q000187:drug effects* / Q000254:growth & development; D008968:Molecular Conformation; D013237:Stereoisomerism; D000516:alpha-Amylases / Q000187:drug effects*
chemical_list: C529751:18-hydroxygibberellic acid 1; D005875:Gibberellins; C007842:gibberellic acid; D000516:alpha-Amylases