Preparation, Structure, and Potent Antifouling Activity of Sclerotioramine Derivatives

A series of 30 sclerotioramine derivatives ( 2 – 31 ) of the natural compound, (+)-sclerotiorin ( 1 ), has been successfully semi-synthesized by a one-step reaction with high yields (up to 80%). The structures of these new derivatives were established by extensive spectroscopic methods and single-crystal X-ray diffraction analysis for 3 , 6 , and 10 . (+)-Sclerotiorin ( 1 ) and its semisynthetic derivatives ( 2 – 31 ) were evaluated for their antifouling activity. Most of them except 6 , 7 , 8 , 12 , and 28 showed potent antifouling activity against the larval settlement of the barnacle Balanus amphitrite . More interestingly, most of the aromatic amino-derivatives ( 13 – 17 , 19 – 21 , 23 , 25 – 27 , and 29 – 31 ) showed strong antifouling activity; however, only two aliphatic amino-derivatives ( 5 and 10 ) had the activity.