Catalytic Divergent [3+3]‐ and [3+2]‐Cycloaddition by Discrimination Between Diazo Compounds

Highly selective divergent cycloaddition reactions of enoldiazo compounds and α‐diazocarboximides catalyzed by copper(I) or dirhodium(II) have been developed. With tetrakis(acetonitrile)copper(I) tetrafluoroborate as the catalyst epoxypyrrolo[1,2‐a]azepine derivatives were prepared in good yields and excellent diastereoselectivities through the first reported [3+3]‐cycloaddition of a carbonyl ylide. Use of Rh2(pfb)4 or Rh2(esp)2 directs the reactants to regioselective [3+2]‐cycloaddition generating cyclopenta[2,3]pyrrolo[2,1‐b]oxazoles with good yields and excellent diastereoselectivities. Katalytische Divergenz: Mit Kupfer(I)‐ oder Dirhodium(II)‐Katalysatoren gelingt die Titelreaktion zwischen Enoldiazoverbindungen und α‐Diazocarboximiden mit hoher Diastereokontrolle und Kreuzselektivität. Drei heterocyclische Produkte mit multicyclischen Azepin‐, Pyrrolizin‐ und Oxazol‐Gerüsten wurden aus den gleichen Diazoverbindungen synthetisiert.