Gratifyingly, the use of Hazari’s10air-stable Pd/SIPr precatalyst3or PEPPSI−SIPr11complex7provides high selectivity for coupling at C−Cl in the room-temperature SM reaction of1with2in THF (Table 1, entries 1−2). Precatalyst 4 bearing the related unsaturated ligand IPr gives comparable selectivity to 3, albeit with reduced yield of the desired product (entry 3). In stark contrast, however, catalysts containing the moderately smaller ligands SIMes and IMes provide the opposite selectivity under otherwise identical conditions(entries 4−5).12−14For example, the Pd/SIMes-catalyzed reaction of 1 with 2 yields 8b in high yield, resulting from selective C−OTf activation (entry 4). Only small amounts of products from C−Cl activation (8a and 8c) are detected with this catalyst.