NiCl redox-active esters. 14v,20 Similarly, ring opening was observed in couplings of cyclopropanecarboxaldehyde (13) leading to product 14 exclusively as the Z-isomer (Figure ). In this case, we attribute ring-opening of the cyclopropane unit to a nickel-catalyzed process involving the intermediacy of 15, potentially involving the initial oxidative addition of a low-valent nickel species to the aldehyde, promoted by Et3SiCl. An experiment employing stoichiometric Ni(cod)2 but lacking the zinc reductant resulted in the formation of product 3a in high yield, suggesting that key organonickel intermediates involved in product formation do not require reduction at the nickel center, but rather that the zinc reductant is involved in catalyst regeneration (Figure ).