Dipole‐Transmissive 1,3‐Dipolar Cycloadditions for the Rapid Construction of Polycyclic N‐Heterocycles: Synthetic and Mechanistic Investigations

The investigation of distinctive dipole‐transmissive dipolar cycloaddition (DTDC) methodology and the formalisation of this concept is reported. A DTDC procedure was able to be developed by taking advantage of the structural complementarity of azide and diazoalkane 1,3‐dipoles. Intramolecular azide‐alkene 1,3‐DCs followed by spontaneous dipole transmission upon work‐up furnished intermediate α‐diazoisoindole and α‐diazoisoquinoline substrates bearing the key secondary diazoalkane 1,3‐dipole. N‐Derivatisation of the intermediate α‐diazoisoindole and α‐diazoisoquinolines with a tethered secondary dipolarophile followed by a subsequent 1,3‐DC allowed for rapid construction of a range of functionalised polycyclic N‐heterocycles. Integrated experimental and theoretical studies established requirements for product formation and revealed the likely mechanistic basis of divergent reactivity observed. Investigation into and formalisation of dipole‐transmissive dipolar cycloaddition (DTDC) methodology is reported. By designing substrates bearing complementary azide and diazoalkane 1,3‐dipoles, we were able to employ integrated experimental and theoretical studies to construct a series of polycyclic N‐heterocycles and rationalise the mechanistic basis of the divergent reactivity observed.