833461-94-2Relevant academic research and scientific papers
Enantioselective synthesis of six-membered palladacycles having metal-bound stereogenic carbons: Isolation and reactivity of palladacycles containing readily accessible β-hydrogens
Burke, Brenda J.,Overman, Larry E.
, p. 16820 - 16833 (2007/10/03)
Five enantiopure palladacycles containing palladium bonded to a stereogenic carbon and an N-coordinated oxindole were synthesized by the reaction of alkenyl aryl triflates 2 and 9 with Pd(0) bisphosphine complexes. Two palladacyclic complexes, 3β and 10aα, were characterized by single-crystal X-ray crystallography. The reactivity of neutral palladacycles 3aβ and 107β was studied in detail. These unusual palladium alkyls, which have three accessible β-hydrogens, are thermally stable at temperatures as high as 120°C. At higher temperature, or at room temperature in the presence of weak acids, these complexes epimerize at the stereogenic carbon bonded to palladium. The mechanism of the acid-promoted epimerization was studied in detail. During this epimerization, cationic palladium alkyls 13/14 and 33 and cationic palladium hydride alkene complexes 31 and 32 are in rapid equilibrium.
