Photoinduced Cycloadditions in the Diversity-Oriented Synthesis Toolbox: Increasing Complexity with Straightforward Post-Photochemical Modifications

Rapid growth of complexity and unprecedented molecular architectures is realised via the excited state intramolecular proton transfer (ESIPT) in o-acylamidobenzaldehydes and ketones followed by [4+2] or [4+4] cycloadditions with subsequent post-photochemical modifications. The approach is congruent with diversity-oriented synthesis, whereby photoprecursors are synthesised in a modular fashion allowing for up to four diversity inputs. The complexity of the primary photoproducts is further enhanced using straightforward and high-yielding post-photochemical modification steps such as reactions with nitrile oxides and nitrones, and Povarov and oxa-Diels-Alder reactions.