Aplysina laevis

Capon, R.J. and MacLeod, J.K. (1987d) Two epimeric dibromo nitriles from the Australian sponge Aplysina laevis. Aust. J. Chem., 40, 341-347. 

A 3 1 mixture of the two epimeric dibromonitriles, 15 and 16, was isolated from an Australian sponge Aplysina laevis (11). Attempts to resolve the mixture by either normal or reverse-phase HPLC, as well as GC, proved unsuccessful. Treatment of ( + )-aeroplysinin-1 (14) with neat trifluoroacetic acid resulted in a good yield of 15 and 16 (3 1 mixture) with a small optical rotation value, which permitted the assignment of the absolute stereochemistries of 15 and 16 as shown. Molecular modeling calculations suggested that the cis isomer 15 was the thermod)mamically more stable isomer. 

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