Palladium-catalyzed hydroarylation of alkynes with arenediazonium salts

The palladium-catalyzed hydroarylation of arenediazonium tetrafluoroborates with alkynes in the presence of triphenylsilane affords stereoselectively hydroarylation products in moderate to high yields. The reaction tolerates a variety of substituents including keto, ester, cyano, and nitro groups and can be performed as a one-pot procedure generating the arenediazonium salt in situ. With ethyl phenylpropynoate as the starting alkyne, the hydroarylation affords ethyl (Z)-2-arylcinnamates stereo- and regioselectively.