Rapid one-pot methodologies to prepare pseudopteroxazole (1) and novel congeners from abundant natural pseudopterosins have been devised. This is highlighted here with the first synthesis of the marine natural product homopseudopteroxazole (2) utilizing a novel, silver(I)-mediated catechol to benzoxazole transformation. Pseudopteroxazoles and isopseudopteroxazoles exhibit potent activity against a range of important Gram-positive pathogens including Mycobacterium spp. and vancomycin-resistant Enterococcus faecium. Several non-natural pseudopteroxazoles exhibited strong activity against methicillin-resistant Staphylococcus aureus, thereby displaying a broader spectrum of antibiotic activity compared to pseudopteroxazole.