Radical mediated deoxygenative alkynylation of Heterocyclic N-oxides under ball milling

Herein, we disclose the first example of stainless steel induced deoxygenative C-2 alkynylation of heterocyclic N-oxides under ball milling via a radical mediated pathway. The current approach showed compatibility to both electron donating and electron withdrawing phenylacetylenes as well as corresponding heterocyclic N-oxides affording the targeted products in moderate to excellent yields including biologically active molecules. Detailed mechanistic investigations based on control experiments and XPS analysis corroborated the significant role of Fe(III) species present in the milling equipment (stainless steel) as well as the mechanical impact of the milling equipment (Fe/Zr-jar/balls), in initiating the reaction via a radical pathway.