Clavatadine A, recently isolated from the marine sponge Suberea clavata, is a specific and potent inhibitor of factor XIa. Factor XIa is a component of the coagulation cascade required for the formation of blood clots and is a potential target for treatment of cardiovascular disease. Our efforts to complete the first total synthesis of clavatadine A feature the carbamoylation of a phenol, prepared by dibromination of homogentisic acid lactone, and an azidoisocyanate, derived from ethyl 5-bromovalerate. From our advanced carbamate intermediate, we envision completing the synthesis of clavatadine A by guanylation and lactone hydrolysis
