MIRABIMIDE-E, AN UNUSUAL N-ACYLPYRROLINONE FROM THE BLUE-GREEN-ALGA SCYTONEMA MIRABILE - STRUCTURE DETERMINATION AND SYNTHESIS

Mirabimide E, a solid tumor selective cytotoxin from the terrestrial b lue-green alga Scytonema mirabile UH strain BY-8-1, possesses an unpre cedented tetrachlorinated ethylene group and has been identified as (5 S,2'R,3'R)-N- thyldecanoyl)-4-methoxy-5-methyl-3-pyrrolin-2-one. The t otal structure, including absolute stereochemistry, of this novel N-ac ylpyrrolinone was concluded from a combination of spectral and chemica l studies, including stereoselective syntheses of three degradation pr oducts, viz. methyl i-8,8,9,9-tetrachloro-3-hydroxy-2-methyldecanoate, ans-5-methyl-6-(5,5',6,6'-tetrachloroheptyl-1-oxa- 3-azacyclohexane-2 ,4-dione, and (5S)-4-methoxy-5-methyl-3-pyrrolin-2-one and the total s ynthesis of mirabimide E itself. The influence of the carbamate ester group on the chemical degradation and synthesis of mirabimide E is des cribed.