Stereocontrolled Preparation of Stereocomplementary Regioisomeric Tricarbonyliron Complexes in Enantiopure Form

The use of ultrasound to form ferralactone complexes from an enantiomerically pure allylic epoxide with an adjacent hydroxymethyl substituent affords a pair of stereocomplementary isomers that offer a regioconvergent route to the same chiral pentadienyliron complex. The enantiomeric purity, CD properties, and absolute configurations of intermediate η4-diene complexes are reported, and X-ray diffraction analysis of a pair of rearranged ferralactone complexes establishes their relative stereochemistries, and confirms their absolute stereochemistries.