Abstract
<jats:p>Azoarenes are widely used as dyes and photoswitches, yet access to new variants remains constrained by a lack of general and modular synthetic methods. Among existing approaches, the Baeyer–Mills reaction is particularly attractive because it avoids unstable diazonium intermediates while exploiting readily available aniline building blocks. Herein, we report "azostitching," a one-pot strategy that expands the Baeyer–Mills reaction by generating nitrosoarenes in situ from commercially available organoboron reagents. Azostitching provides rapid access to structurally diverse azoarenes and azoheteroarenes bearing a variety of functional groups. By leveraging the broad availability of organoboron reagents, azostitching substantially expands the accessible chemical space for azoarene discovery. The utility of the platform is demonstrated through the synthesis of numerous new azoarenes and azoheteroarenes, functionalization of bioactive molecules, and evaluation of the photophysical properties of new photoswitches.</jats:p>