2007 Fiscal Year Final Research Report Summary
Synthesis and Reactions of Water-resistant Organotransition Metal Complexes
| Project/Area Number |
17350025
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Inorganic chemistry
|
|---|
| Research Institution | Tokyo University of Agriculture and Technology |
|---|
Principal Investigator |
KOMIYA Sanshiro Tokyo University of Agriculture and Technology, Institute of Symbiotic Science and Technology, Professor (00111667)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
HIRANO Masafumi Tokyo University of Agriculture and Technology, Institute of Symbiotic Science and Technology, Associate Professor (70251585)
KOMINE Nobuyuki Tokyo University of Agriculture and Technology, Institute of Symbiotic Science and Technology, Assistant Professor (90302918)
|
|---|
| Project Period (FY) |
2005 – 2007
|
| Keywords | Water-soluble organotransition metal complex / Reductive elimination / Allylation / Palladium / gold / Water / hexane biphasic system / Regioselectivity |
|---|
| Research Abstract |
Series of water-soluble dialkylpalladium and -gold complexes were prepared by the ligand exchange reactions with water-soluble ligands such as TPPTS, TPPMS and trihydroxymethylphosphine, which were characterized by NMR and IR spectroscopy and chemical reactions. They are practically stable in water at room temperature. Thermolysis of these complexes caused reductive elimination involving carbon-carbon bond formation in addition to hydrolysis. For gold complex, reductive elimination in water was much faster than that in organic solvents, suggesting faster ligand dissociation or reductive elimination in water. For palladium complex, hydrolysis was the main pathways in H_2O. However, unexpected inverse solvent isotope effect was observed. Namely, in D_2O reductive elimination became much faster than hydrolysis, suggesting that interaction with proton is considered to be crucial step for reductive elimination. Addition of electron deficient olefin having carbonyl group showed strong accele
… More
ration effect causing only reductive elimination. Mechanisms for reductive elimination of both dialkylpalladium and -gold complexes were proposed based on kinetic studies.
Water-soluble allylpalladium complexes were also prepared by the reaction of allylpalladium dimmer with corresponding water-soluble ligands. They are al ; so stable in water. Stoichiometric allylation of nucleophiles such as amine, thiol and carbonyl compounds were achieved in water.
Catalytic allylation of these nucleophiles were also successful in the presence of Pd(OAc)_2/TPPTS in water/hexane biphasic system. Especially, allylation of benzenethiol gave good results. Water solution involving catalyst can be used repeatedly without catalytic activity loss. One interesting fact in this allylation is stirring speed of the reaction mixture controls the regioselectivity of the allylation. The faster the stirring speed was, the sterically congested carbon of the allyl unit was reacted to give branched allylphenylthioether. This is quite unusual that the stirring speed controls the reaction selectivity. Highly oriented structure of alylpalladium active species may be responsible for this fact, in which the o-allyl part stay preferably in the hexane solvent and SN2' type reaction with thioll gave branched product predominantly. Less
|
