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

Intramolecular cycloadditions of photogenerated azaxylylenes provide access to unprecedented polyheterocyclic scaffolds, suitable for subsequent postphotochemical modifications to further grow molecular complexity. Here we explore approaches to rapid "assembly" of novel photoprecursors with nitrogen/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, minimal number of rotatable bonds, and a high content of sp3 hybridized carbons. The modular "assembly" of the photoprecursors and potential variety of postphotochemical modifications of primary photoproducts provide framework for combinatorial implementation of this synthetic strategy.