Visible‐Light Promoted Intramolecular <i>para</i>‐Cycloadditions on Simple Aromatics
Maurizio Chiminelli, Andrea Serafino, Davide Ruggeri, Luciano Marchiò, Franca Bigi, Raimondo Maggi, Max Malacrìa, Giovanni Maestri
Abstract
Dearomative cycloadditions are a powerful tool to access a large chemical space exploiting simple and ubiquitous building blocks. The energetic burden due to the loss of aromaticity has however greatly limited their synthetic potential. We devised a general intramolecular method that overcomes these limitations thanks to the photosensitization of allenamides. The visible-light-promoted process gives complex [2.2.2]-(hetero)-bicyclooctadienes at room temperature, likely through the stabilization of transient (bi)radicals by naphthalene. The reaction tolerates several valuable functionalities, offering a convenient handle for a myriad of applications, including original isoindoles and metal complexes.