Skeletal Rearrangement of Biaryls via Rhodium-Azirine Intermediate: A Route to Solid-State Emissive Polycyclic Sulfamates

We report a rhodium-catalyzed cascade transformation
of biaryl
alkynylsulfamates that enables access to rigid, spirocyclic cycloheptatrienes
with strong solid-state fluorescence. Building on prior work confirming
selective 7-endo nitrene–alkyne cyclization, our design leverages
skeletal rigidity to promote a thermally driven electrocyclic ring
opening. Detailed mechanistic studies, supported by density functional
theory (DFT) calculations, reveal a key rhodium-bound azirine intermediate
that undergoes a dearomative single-carbon insertion into the biaryl
framework. This reaction proceeds via a distinct, noncarbene-based
pathway, expanding the scope of nitrene-mediated rearrangements beyond
classical Büchner-type mechanisms. The method provides a modular
route to structurally complex and photoactive scaffolds through rationally
designed cascade processes.