200 likes | 356 Views
High-Oxidation-State Palladium Catalysis. 报告人:刘槟. 2010 年 10 月 23 日. Introduction. In 1986 , the first unequivocal trialkylpalladium(IV) complex, [PdIMe 3 (bpy)],was isolated and characterized by X-ray analysis. Acc. Chem. Res . 1992 ,25,83-90. Advantages.
E N D
High-Oxidation-State Palladium Catalysis 报告人:刘槟 2010年10月23日
Introduction • In1986 , the first unequivocal trialkylpalladium(IV) complex, [PdIMe3(bpy)],was isolated and characterized by X-ray analysis. Acc. Chem. Res. 1992,25,83-90
Advantages • Some advantages compared to Pd(0)/Pd(II) catalysis: • Pd(IV) species are often resistant to β-H elimination process • Pd(IV) species undergo facile reductive elimination. (like C-C bond formation) • Pd(II)/Pd(IV) catalyzed reactions are operationally simple and do not require the careful exclusion of air (especially O2) and moisture. Chem. Soc. Rev., 2010, 39, 712–733
C-C Coupling Angew. Chem., Int. Ed., 1997, 36, 119
J. AM. CHEM. SOC. 2006, 128, 4972-4973 Pd0/II versus Proposed PdII/IV Mechanism for Indole Arylation
carbon-carbon bond formation from unactivated alkyl C-H bond J. AM. CHEM. SOC. 2005, 127, 13154-13155
C-O and C-X Bond Formation J. AM. CHEM. SOC. 2004, 126, 2300-2301
C-N Bond Formation Proposed Catalytic Cycle J. AM. CHEM. SOC. 2005, 127, 7690-7691
Domino Catalysis Involving Pd(IV) Catalysts J. AM. CHEM. SOC. 2007, 129, 5836-5837
First example of enantioselective palladium(IV) catalysis J. AM. CHEM. SOC. 2009, 131, 3452–3453
Problems • Little is known about the ligand effect of Pd(IV) complexes • Enantioselective synthesis using chiral ligands through Pd(IV) intermediates has not been forthcoming • Applications to natural product synthesis are lacking • Detailed mechanistic investigation
Conclusion The development of palladium(IV) catalysis has just begun, it has already enabled the development of a number of significant new transformations. These reactions are marked by their high selectivity and synthetic robustness, and almost all are based on the use of catalysts that are generated in situ from commercially available palladium salts.