Biosynthesis of cyclic bromo-ethers, derived from red algae

Various halogenated organic compounds, originated from marine livings, have been well-known over five decades. Particularly, cyclic bromo-ether have attracted many chemists to study their existence, biogenetic syntheses and artificial syntheses, owing to their unique structures. Laurencia species produce eight-membered ethers as major products, although their syntheses by chemical procedures are generally difficult. These compounds are divided into laurenan and lauthisan groups based on the type of ring formation. The laurenan compounds are characteristic in respect of C 6-S and C 7-S configurations, while the lauthisan series have R and R at the requisite positions. It has been proposed without any proof that the bromine atoms in the marine compounds could be introduced via bromo cationic species, generated by the two-electron oxidation of bromide ion with bromoperoxidase (BPO) and hydrogen peroxide. We studied on the enzymatic formation of these bromo-ethers, and found that both series of laurenan and lauthisan compounds could be biosynthesized directly from linear C 15 compounds, laurediols. Herein, we mention our study of these natural products, and the recent studies around this field.