Polypropionates from the South African Marine Mollusk Siphonaria oculus

Three new polypropionate metabolites, 6Z,8E-Delta(8)-siphonarienfuranone (1), 6E,8E-Delta(8)-siphonarienfuranone (2), and 6E,8E-3-hydroxy-4,6,8,10,12-pentamethylpentadeca-6,8-dien-5-one (3), and the known polypropionate siphonarienfuranone (4) were isolated from the intertidal South African marine mollusk Siphonaria oculus. Evidence is presented to suggest that 1, 2, and 4 may cyclize from an acylic precursor on chromatographic workup of the acetone extract of this mollusk