Regioselective syn-1,2-hydroarylation of internal alkynes†

The regioselective hydro-functionalization reaction is a powerful method to convert readily available alkynes into structurally diverse olefins. Such an efficient syn-1,2-hydroarylation of yne-acetates is described herein using aryl diazonium salts and silanes as aryl and hydride sources, respectively. The transformation shows excellent functional group tolerance and applications to late-stage functionalization, providing straightforward access to trisubstituted allyl acetates. DFT analysis sheds light on the mechanism, particularly on the role of DMSO solvent in assisting the Si–H bond cleavage.