This paper reports the syntheses of five analogues of subergorgic acid: methyl ester of subergorgic acid （3）

9-hydroxyl subergorgic acid （4）

2

3-epoxidesubergorgic acid（5）

8-hydroxyl-⊿

7

8

-ene-subergorgic acid （7） and its methyl ester（6）.An attempt has been made to survey the relationship between the structure of subergorgic acid and its bioactivity. Compounds （3） and （4）

though similar to subergorgic acid in structure

possess almost no toxicity. As soon as an epoxy or a double bond is functionalized to the α

β-position of the carboxyl or the earbonyl group respectively

its toxicity almost disappears too

Therefore. it can be thought that the carboxyl and carbonyl groups are responsible for the bioactivity of subergorgic acid.