The purpose of this project is to develop a number of organoironcarbonyl reagents to be used in the synthesis of a number of natural products which are important in the health sciences. The type of organoironcarbonyl complex on which our work has focused thus far are tetracarbonyliron complexes of alkenes. In one phase of this work we have already prepared a number of alkenes with geminal carbonyl substituent, including methylenemalonates and alpha-acylacrylates, which are capable of forming stable tetracarbonyliron complexes. These alkenes and the corresponding complexes are being developed as reagents for the construction of polycyclic fused ring natural products. A specific objective of this part of our work is the total synthesis of estrone, a centrally important steroidal hormone. In another phase of this work, a new approach to macrolide synthesis is being developed through the use of tetracarbonyliron complexes of acrylate esters which incorporate a potential internal nucleophile. Formation of the macrolide ring involves generation of the internal nucleophile with base followed by intramolecular nucleophilic addition of nucleophile to the acrylate ester. The scope of this reaction type is currently being established after which the method will be applied to the synthesis of specific naturally occurring macrolides.