A series of deuterium labeling experiments showed that Pd migrations during an intermolecular asymmetric Heck reaction between phenyl triflate and various deuterated 2, 3- dihydrofurans (2b, 2c, 2d, 2e) occurs exclusively by either syn-1, 2-dyotropic shifts or a syn- chain-walking mechanism; no evidence was observed to support anti-1, 2-dyotropic shifts or anti-β-H Pd eliminations during the formation of 6 and 7.
