Utah Valley University 1 article published in JoVE Chemistry A Direct, Early Stage Guanidinylation Protocol for the Synthesis of Complex Aminoguanidine-containing Natural Products Christopher E. Malmberg1, Stephen Chamberland2 1Department of Chemistry, Central Washington University, 2Department of Chemistry, Utah Valley University Here, we present a protocol for direct, early stage guanidinylation that enables rapid total synthesis of aminoguanidine-containing small organic molecules. An advanced synthetic intermediate used in the synthesis of a blood coagulation factor XIa inhibitor was prepared using this protocol.