Total synthesis of (15R)- and (15S)-F2t-isoprostanes by a biomimetic process using the cyclization of acyclic dihydroxylated octa-5,7-dienyl radicals

We report a new route to F-2t-IsoP (formerly named 8-epi-PGF(2alpha)) using a biomimetic radical cyclization of a highly functionalized C20 precursor. The strategy employed gives a beta-hydroxy free radical followed by molecular oxygen trapping, which is an unusual method for quenching carbon free radicals. We observed the formation of unique diastereoisomers (15R)- and (15S)-F-2t-IsoP. This result is consistent with a strong stereoelectronic control associated with a steric effect initiated by the side chains alpha and omega on the cyclopentane ring.