Three new vinyl acetylenes from the marine red alga laurencia

The structures of three new halogenated vinyl acetylenes are described which are natural products from various species of the red seaweed Laurencia. The structure of chlorofucin (1) isolated from Laurencia snyderae was determined by X-ray diffraction analysis. Poiteol (2) was isolated from Laurencia poitei and its structure was also determined by single crystal X-ray diffraction experiments. The structure of obtusenyne (3) was based on a combination of chemical and spectral methods. The ¹³C NMR spectra of these new compounds are presented and assignments made.