Isolation and Synthesis of Azuriaplysins A and B, Bromoditerpenes with an a-Methylene Carbonyl from the Sea Hare Aplysia kurodai

New bromoditerpenes having an alpha-methylene carbonyl structure, azuriaplysins A (1) and B (2), were isolated from the sea hare Aplysia kurodai. Their relative stereostructures were determined based on one-and two-dimensional NMR spectroscopic analysis. In addition, the absolute stereostructures were determined by the total synthesis of both enantiomers of azuriaplysins A (1) and B (2), the key points of which were bromocyclization of farnesol and optical resolution of a key intermediate. Azuriaplysin B (2) and its enantiomer exhibited moderate cytotoxicity against HeLa S3 cells.

Automated summary

Two new bromoditerpenes, azuriaplysins A (1) and B (2), were isolated from the sea hare Aplysia kurodai. Their relative stereostructures were determined by NMR analysis, and their absolute stereostructures were determined through total synthesis. Azuriaplysin B (2) and its enantiomer exhibited moderate cytotoxicity against HeLa S3 cells.