Apakaochtodenes A and B:  Two Tetrahalogenated Monoterpenes from the Red Marine Alga Portieria hornemannii

The structure of apakaochtodene A, the minor isomer of two tetrahalogenated ochtodene monoterpenes, isolated from the red marine alga Portieria hornemannii (Lyngbye) Silva has been identified as 6(S*)-bromo-1,4(S*),8(R*)-trichloro-2(Z)-ochtodene (<BO>1</BO>) by NMR spectral and X-ray crystallographic analysis. Its geometrical isomer, apakaochtodene B (<BO>2</BO>), which could not be separated from <BO>1</BO> and thus characterized as a 95:5 mixture of <BO>2</BO>:<BO>1</BO> had ¹H and ¹³C NMR spectral characteristics similar to previously known ochtodene (<BO>3</BO>) and the related tetrahalogenated monoterpene <BO>4</BO>.