[3 + 2] cycloaddition between cyclic diaryl λ3-bromanes and nitrones towards the formation of dihydrobenzisoxazoles and an evaluation of regioisomeric bioactivity †

Here, an example of an efficient construction of important dihydrobenzisoxazole cores from cycloaddition reactions between cyclic diaryl λ³-bromanes as the aryne precursors and nitrones is reported. Many dihydrobenzisoxazole-containing compounds were synthesized under transition-metal-free conditions, and this approach was found to feature a broad substrate scope, good functional group compatibility and reasonable regioselectivities. Preliminary bioactivity evaluations demonstrated that multiple examples of these dihydrobenzisoxazoles showed potential activities against porcine reproductive and respiratory syndrome virus (PRRSV).