Annonaceous Acetogenins from the Seeds of Annona squamosa. Non-adjacent Bis-tetrahydrofuranic Acetogenins.

摘要: Four non-adjacent bis-tetrahydrofuranic acetogenins, named squamostatins-B (2), -C (3), -D (4) and -E (5), have been isolated from the petroleum ether extract of Annona squamosa seeds. The structures these acetogenins established on basis spectral evidence. C-15/C-16-threo, C-19/C-20-threo, C-23/C-24-erythro stereochemistry was assigned for -D, whereas C-23/C-24-threo assigened squamostatins-C -E. All including squamostatin-A, to C-12/C-15-trans, C-20/C-23-trans by 13C-NMR comparison with synthetic model mono-tetrahydrofuranic compounds. An improved C-NMR assignment squamostatin-A is presented.