HYDROLYTIC BREAKDOWN OF THE EUPLOTINS, HIGHLY STRAINED, ADAPTIVE, HEMIACETAL ESTERS OF THE MARINE CILIATE EUPLOTES-CRASSUS - A MIMIC OF DEGRADATIVE PATHWAYS IN NATURE AND A TRICK FOR THE ASSIGNMENT OF THE ABSOLUTE-CONFIGURATION

Euplotin C ((+)-3), the most abundant of the niche-exploitation terpen oids oi the marine ciliate morphospecies Euplotes crassus, was found i o undergo degradation in mildly basic H2O/MeOH by initial hydrolysis o f the acetate group, followed by, in turn, hydrolytic ring-A and ring- C opening and ring-A reclosure with indiscriminate C(1)/C(15) methanol trapping to give four diastereoisomeric aldehydic hemiacetals 5-8 in similar proportions; 7, as a model for iis congeners, proved biologica lly inactive. From these, the absolute configuration was assigned via Mosher's ester methodology. These processes may be assumed to mimic in activation of the euplotins in sea water. Degradation of (+)-3 in eith er stronger bare or acidic medium was also examined.