Mn‐Catalyzed Dehydrocyanative Transannulation of Heteroarenes and Propargyl Carbonates through C−H Activation: Beyond the Permanent Directing Effects of Pyridines/Pyrimidines

Pyridines/pyrimidines are common and effective directing groups in C−H activation. However, they are poorly functionalizable heteroarenes. Reported in this work is Mn‐catalyzed dehydrocyanative transannulation between three classes of heteroarenes and propargyl carbonates. The pyridyl/pyrimidyl groups in the heteroarenes initially function as directing groups to enable C−H allenylation; they then undergo intramolecular Diels–Alder/retro‐Diels–Alder reactions with the allene moiety to afford fused carbo/heterocycles. Three key intermediates at different stages of the reaction were isolated. Doppelrolle: Bei einer Mn‐katalysierten Transanellierung von Heteroarenen und Propargylcarbonaten wirken die Pyridyl/Pyrimidyl‐Gruppen zunächst als dirigierende Gruppen für eine C‐H‐Allenylierung; danach gehen sie einen intramolekularen Diels‐Alder/Retro‐Diels‐Alder‐Prozess mit dem Allen ein, wobei sechsgliedrige Carbo‐/Heterocyclen entstehen. Drei Schlüsselintermediate aus unterschiedlichen Reaktionsstadien wurden isoliert.