The precise choreography of installation and substituents embedded on the guanidine subunits required extensive empirical investigations as this unpredictable chemical puzzle involved the selective manipulation of three different amines. An array of different guanidine donors was surveyed across a range of differentially protected triamines as briefly summarized in Scheme 1B . For instance, attempted cyclizations of the N(1,3)-diamine 21 suffered from low overall efficiency due to challenges in protecting group compatibility . Constructs such as 22, bearing a suitably protected guanidine (G2) at N(2) followed by cyclization of the N(1,3)-diamine onto a guanidine donor (G1) failed due to competitive cyclizations of N(1,3) onto G2. A differentially guanidinylated intermediate such as 23, leaving the N(3) position unprotected also failed as cyclization was observed on G2 rather than G1. It was finally found that structures such as 24, wherein N(3) and N(2) were guanidinylated resulted in the desired cyclization. This sequence could be conducted in a single pot (vide infra) and due to the modular nature of the radical coupling, dozens of substrate types could be prepared and evaluated (see SI for a more complete roadmap of these approaches).