Structure Elucidation of Gibberellin A32 and Its Acetonide

The structures of two gibberellin-like substances isolated from the immature seeds of Prunus persica, tentatively named PG–I and PG–II, were elucidated. PG–I was an ammonium salt of a novel gibberellin, ent-3α,10,12β,13,15α-pentahydroxy-20-norgibberella-l,16-diene-7,19-dioic-19,10-lactone (1), to which gibberellin number A₃₂ was allocated. PG–II was shown to be gibberellin A₃₂ acetonide (7), and concluded to be an artifact produced from gibberellin A₃₂ in the isolation process.