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 eta(4)-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. (C) 2000 Elsevier Science Ltd. All rights reserved.