Two Epimeric Dibromo Nitriles From the Australian Sponge Aplysina laevis

Two dibromo nitriles, (1′R,5′S,6′S)-2-(3′,5′-dibromo-1′,6′-dihydroxy-4′-oxocyclohex-2′- enyl) acetonitrile (5) and the (l′R,5′R,6′S) epimer (6), possessing antimicrobial activity, have been isolated from the sponge Aplysina laevis (Carter). Cometabolites (+)-aeroplysinin-1 (1) and the dibromo ketone (2) were also identified. Structures (5) and (6) were assigned on the basis of spectroscopic evidence and synthesis from (1).