Equilibrium Study of Pd(dba)2and P(OPh)3in the Pd-Catalyzed Allylation of Aniline by Allyl Alcohol.
Reaction of Pd(dba)2and P(OPh)3shows a unique equilibrium where the Pd[P(OPh)3]3complex is favored over both Pd(dba)[P(OPh)3]2and Pd[P(OPh)3]4complexes at room temperature. At a lower temperature, Pd[P(OPh)3]4becomes the most abundant complex in solution. X-ray studies of Pd[P(OPh)3]3and Pd(dba)[P(OPh)3]2complexes show that both complexes have a trigonal geometry with a Pd-P distance of 2.25 Å due to the π-acidity of the phosphite ligand. In solution, pure Pd(dba)[P(OPh)3]2complex equilibrates to the favored Pd[P(OPh)3]3complex, which is the most stable complex of those studied, and also forms the most active catalytic species. This catalyst precursor dissociates one ligand to give the reactive Pd[P(OPh)3]2, which performs an oxidative addition of nonmanipulated allyl alcohol to generate the π-allyl-Pd[P(OPh)3]2intermediate according to ESI-MS studies.
Department of Chemistry, BMC, Uppsala University , Box 576, 751 23 Uppsala, Sweden.
Supaporn
S
Sawadjoon
Department of Chemistry, Ångström Laboratories, Uppsala University , Box 523, 751 20 Uppsala, Sweden.
Andreas
A
Orthaber
Department of Chemistry, BMC, Uppsala University , Box 576, 751 23 Uppsala, Sweden.
Per J R
PJ
Sjöberg
Department of Structural Chemistry, Stockholm University , 106 91, Stockholm, Sweden.
Lars
L
Eriksson
Department of Chemistry, BMC, Uppsala University , Box 576, 751 23 Uppsala, Sweden.
Joseph S M
JS
Samec