“Dial Up and Lock In”: Asymmetric organo-Brønsted acid catalysis incorporating stable isotopes

An operationally simple organo-Brønsted-acid-catalyzed asymmetric and regioselective “dial up and lock in” of one or more stable isotopes into organic compounds is unknown. Here, we describe a newly designed, chemically versatile protocol mediating single- or multiple-isotope incorporation into aziridines via a one-pot, three-component, two-step process. By exploiting easy-to-generate isotope-derived starting materials, it allows complete control of isotope positioning, affords >95 atom % isotope incorporation, and generates cis-aziridines with excellent optical activities and regioselectivities. Demonstrating a “low entry point,” and thus easy access to a broad range of researchers, it requires no specialist laboratory equipment and employs readily attainable reaction conditions. Demonstrating their utility, the aziridines are easily transformed into sought-after chiral non-racemic α-amino acids appended with one to three (or more) identical or different isotopes. The widespread use of these compounds ensures that our methodology will be of interest to biological, medicinal, pharmaceutical, agrochemical, biotechnology, materials, and process chemists alike.