Dysidea absolute stereochemistry

The simple herbacic acid (938) was isolated from Dysidea herbacea from the Great Barrier Reef, and may be a precursor to more complex trichloromethyl metabolites (990). Another collection of Dysidea sp. from Australia s Great Barrier Reef yielded five new metabolites (939-943) for which the absolute stereochemistry was determined by correlation with (-)-(.S )-4,4,4-trich loro-3-methyl butanoic acid (991). Dysidea herbacea from the Great Barrier Reef contains (-)-neodyside-nin (944), which is an isomer of the well-known and often isolated dysidenin. 

The Red Sea sponge Lamellodysidea herbacea contains the new dysidamides D-H (960-965) and ring-opened analogs 966 and 967 998). As has been pointed out several times 999), the determination of absolute stereochemistry of the Dysidea polychlorinated peptides has been difficult and revisions are not uncommon. The X-ray crystal structure of a zinc chelate of dechlorinated dysidenin has confirmed its absolute configuration as (55,135) as shown in UU 999). 

A new class of sesterterpenes in which the middle three units of a penta-isoprenoid chain cyclised into a bicyclic system, leaving the first and the last isoprenoids to substitute the decaline moiety, was isolated from sponges of genus Dysidea and Ircinia. From the Palauan Dysidea sp. was isolated dysideapalaunic acid (107) that inhibited the aldose reductase [124]. An inhibitor of aldose reductase is expected to prevent neuropathy or cataract as a complication of diabetes. These diseases are caused by the accumulation of sorbitol in the peripheral nerve or the crystalline lens, as a result of enzymatic reduction of glucose by the aldose reductase in the sorbitol cycle [125,126]. The absolute stereochemistry of dysideapalaunic acid was established by its total synthesis [127,128],... 

De Laszlo, S.E., and P.G. Williard Total Synthesis of (+ )-Demethyldysidenin and ( —)-Demethylisodysidenin, Hexachlorinated Amino Acids from the Marine Sponge Dysidea herbacea. Assignment of Absolute Stereochemistry. J. Am. Chem. Soc. 107, 199 (1985). 

De Laszlo SE, Williard PG. Total synthesis of (+)-demethyl-dysidenin and (—)-demethylisodysidenin, hexachlorinated amino acids from the marine sponge Dysidea Herbacea. Assignment of absolute stereochemistry. J. Am. Chem. Soc. 1985 107(1) 199-203. 

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