Arylazo Sulfones as 1,3-Dipole Acceptors in the (Photo)-Micellar van Leusen Triazole Synthesis

Arylazo sulfones represent a valuable class of organic compounds, which can be exploited as safer and bench-stable analogues of diazonium salts. Notwithstanding their significant applications in light-triggered reactions as precursors of either diazenyl or aryl radicals, their reactivity as 1,3-dipole acceptors has been poorly investigated. The present manuscript addresses the study of a [3 + 2] cycloaddition reaction between arylazo sulfones and α-acidic isonitriles such as TosMIC and related analogues. Reaction conditions have been optimized in a micellar medium, namely CTAC 2% aq solution, in order to afford sustainable synthetic access to 1,2,4-triazole derivatives, a relevant scaffold in medicinal and material chemistry. The substrate scope has been showcased with 24 examples (24-90% yield) with good functional group tolerability. Worthy of note, solution NMR techniques have been applied to characterize the reaction at the molecular level, providing a groundwork to drive a rational choice of the micellar medium on the basis of the substrates' chemical nature. Moreover, the recyclability of the micellar medium was investigated via dynamic light scattering (DLS) analyses.