Sarcophytonolides are cembranolide diterpenes isolated from the soft corals of genus Sarcophyton. Unified total synthesis of sarcophytonolides C, E, F, G, H, and J and isosarcophytonolide D was achieved. The synthetic routes feature NaHMDS- or SmI-mediated fragment coupling, alkoxycarbonylallylation, macrolactonization, and transannular ring-closing metathesis. These total syntheses led to the absolute configurational confirmation of sarcophytonolide H, elucidation of sarcophytonolides C, E, F, and G, and revision of sarcophytonolide J and isosarcophytonolide D. We also evaluated the antifouling activity and toxicity of the synthetic sarcophytonolides H and J and their analogues as well as the cytotoxicity of the synthetic sarcophytonolides and the key synthetic intermediates.

Xylemin (6) and its designed structural analogues 18-23, N-(4-aminobutyl)alkylamines, were synthesized by 2nitrobenzenesulfonamide (Ns) strategy. Investigation of the improved synthesis of 20-23 resulted in the development of onestep synthesis of these analogues from the commercially available corresponding ketones. Biological assessment of the synthetic molecules elucidated that xylemin (6) and the analogue N-(4aminobutyl)cyclopentylamine (21) promoted the expression level of thermospermine synthase ACAULIS5 (ACL5) and enhanced xylem formation. In addition, xylemin (6) was found to significantly promote lateral root formation, whereas xylemin analogues 18-23 including 21 did not. These results indicate that the analogue 21 has the potential as a novel inhibitor of thermospermine synthesis to work specifically in xylem differentiation.