Next we addressed the question of how the minor trans-arylated products were formed. Using conditions with elevated temperatures (110 °C) was shown to cause epimerization of cisarylated products and so reduce dr. On the other hand, resubjecting cis-arylated piperidine 2c to the optimal reaction conditions, in the absence of aryl iodide, gave no cis-to-trans epimerization at the lower temperature. This suggested an alternative route to the trans-diastereoisomer via a minor trans-palladacycle intermediate. To test the viability of a direct trans-arylation, we examined a second arylation using a different aryl iodide to provide a stereochemical marker (Scheme 3).