Transition‐Metal‐Free Synthesis of Nitrogen Containing Heterocycles With Fully Substituted N ‐fused Pyrrole Rings

The efficient synthesis of C‐2 alkylated indolizine, pyrrolo[1,2‐ a ]isoquinoline, and pyrrolo[1,2‐ a ]quinoline derivatives utilizing a single reactivity platform is described. Employing a [3+2] dipolar cycloaddition reaction between heterocyclic N ‐ylides and allenoates, the incorporation of C‐2 alkyl substituents was achieved resulting in various N ‐fused heterocycles with a fully substituted pyrrole ring. This metal‐free route employing allenoates as a dipolarophile solves the longstanding limitations of functional diversity at the C‐2 position and the efficient creation of the pyrrolo[1,2‐ a ]quinoline motif.