The focus of this research is to develop synthetic methodology using the condensations of pentacovalent oxaphospholenes (P(V)'s) with various electrophiles for the production of highly substituted phosphonates. The methodology will be be applied to the synthesis of phosphonate analogs of biologically active organophosphates. The reactivities of P(V)'s with differing ligand on phosphorus and the mechanism(s) of the condensations between P(V)'s and electrophiles will also be explored. With this renewal award, the Synthetic Organic Program and the Office of Mutlidisciplinary Activities are supporting the research of Dr. Cynthia K. McClure of the Department of Chemistry at Montana State University. Professor McClure will focus her work on developing methods for the preparation of phosphonate containing compounds of biological interest as antimetabolites and enzyme active probes. Compounds of this type could have medicinal value as antivirals, antibiotics, antiacidosis agents and could exhibit herbicidal and insecticidal activity.