Geometry and halogen regiochemistry determination of vicinal vinyl dihalides by 1H and 13C NMR. Application to the structure elucidation of prefuroplocamioid,an unusual marine monoterpene

Empirical rules based on 13C and 1H NMR spectroscopy to determine the regiochemistry and geometry of the 1,2-bromochloro vinyl portion of naturally occurring or synthetic compounds containing this functionality are proposed. The key feature of the method comes from the comparison of the spectral data of the new monoterpene metabolite, prefuroplocamioid, isolated from Plocamium cartilagineum, with those of other marine monoterpenes, as well as with some model compounds found in the literature.