Abstract:  Marine natural products often have complex structures and potent biological activities; however, little is understood regarding how their molecular structure correlates with function or what biological targets or pathways are involved.  Through rapid and efficient chemical syntheses of bioactive marine natural products we are able prepare ample quantities of material to explore both structure-activity relationships as well as target identification studies.  To accomplish these goals, novel and expedient approaches to complex heterocyclic scaffolds are required.  Herein, the monanchocidin and synoxazolidinone families of natural products will be discussed along with how these efforts have revealed several new methods for heterocycle synthesis.