A convergent, nine‐step (LLS), enantioselective synthesis of α‐cyclopiazonic acid and related natural products is reported. The route features a) an enantioselective aziridination of an imine with a chiral sulfur ylide; b) a bioinspired (3+2)‐cycloaddition of the aziridine onto an alkene; and c) installation of the acetyltetramic acid by an unprecedented tandem carbonylative lactamization/N−O cleavage of a bromoisoxazole. A convergent, nine‐step (longest linear sequence), enantioselective synthesis of α‐cyclopiazonic acid is reported featuring a) an enantioselective aziridination; b) a bioinspired (3+2)‐cycloaddition; and c) an unprecedented tandem carbonylative lactamization/N−O cleavage of a bromoisoxazole to install the acetyltetramic acid.