Copper(I)-catalyzed sulfonylation of (2-alkynylaryl)boronic acids with DABSO

The scaffold of benzo[b]thiophene 1,1-dioxides can be easily constructed through a copper(I)-catalyzed insertion of sulfur dioxide into (2-alkynylaryl)boronic acids. The reaction proceeds in the presence of 10 mol% copper(I) acetate in DMF at 100 degrees C with high efficiency, leading to benzo[b]thiophene 1,1-dioxides in good to excellent yields. The sulfonyl group can be easily introduced via insertion of sulfur dioxide and the subsequent intramolecular 5-endo cyclization affords the core of benzo[b]thiophene 1,1-dioxide.