Conformationally Constrained Penta(hetero)cyclic Molecular Architectures by Photoassisted Diversity-Oriented Synthesis

Intramolecular cycloadditions of photogenerated azaxylylenes provide access to unprecedented polyheterocyclic scaffolds, which are suitable for subsequent postphotochemical modifications to further grow molecular complexity. Here, we explore approaches to the rapid assembly of new photoprecursors with nitrogen- or oxygen-rich tethers capable of producing potential pharmacophores and also compatible with subsequent 1,3-dipolar cycloadditions to furnish pentacyclic heterocycles with new structural cores, a minimal number of rotatable bonds, and a high content of sp(3)-hybridized carbon atoms. The modular assembly of the photoprecursors and the potential variety of postphotochemical modifications of the primary photoproducts provide a framework for the combinatorial implementation of this synthetic strategy.