Metathesis studies to cyclic enol phosphonamidates

The development of cyclic, six membered enol phosphonamidates utilizing the ring-closing metathesis (RCM) reaction is discussed. Phosphonamidic monochloridates are generated and further functionalized to an array of acyclic, enol phosphonamidates. Subsequent metathesis affords both desired RCM product and corresponding cross metathesis (CM) dimer. Efforts to optimize formation of desired RCM product, while minimizing CM products are discussed, with interesting steric and electronic factors governing reactivity patterns. This strategy allows for generation of cyclic enol phosphonamidates, with ultimate application to C(6)-substituted analogs of the anti-cancer agent, cyclophosphamide.