syn- and anti-[Pd(eta3-allyl)] complexes. Addition of chloride triggers a true memory effect, in which the allylic terminus originally bearing the leaving group has a higher reactivity. The latter effect, termed regioretention, can be rationalized by ionization from a palladium complex bearing a chloride ion, forming an unsymmetrically substituted [Pd(eta3-allyl)] complex. DFT calculations verify that
Influences on the Regioselectivity of Palladium-Catalyzed Allylic Alkylations
作者:Uli Kazmaier、Daniel Stolz、Katja Krämer、Franz L. Zumpe
DOI:10.1002/chem.200701332
日期:2008.1.28
Chelated amino acid ester enolates are excellent nucleophiles for palladium-catalyzed allylicalkylations. These enolates react rapidly at -78 degrees C and in general without isomerization of pi-allyl palladium complexes. Therefore, they are good candidates for mechanistic studies and regioselective reactions. Terminal pi-allyl palladium complexes are preferentially attacked at the least hindered