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 Some advantages compared to Pd(0)/Pd(II) catalysis: 1.Pd(IV) species are often resistant to β-H elimination process 2.Pd(IV) species undergo facile reductive elimination. (like C-C bond formation) 3.Pd(II)/Pd(IV) catalyzed reactions are operationally simple and do not require the careful exclusion of air (especially O 2 ) and moisture. Chem. Soc. Rev., 2010, 39, 712–733

C-C Coupling Angew. Chem., Int. Ed., 1997, 36, 119

J. AM. CHEM. SOC. 2005, 127,

Chem. Soc. Rev., 2010, 39, 712–733

Pd0/II versus Proposed PdII/IV Mechanism for Indole Arylation J. AM. CHEM. SOC. 2006, 128,

carbon-carbon bond formation from unactivated alkyl C-H bond J. AM. CHEM. SOC. 2005, 127,

Mechanistic Considerations

J. AM. CHEM. SOC. 2002, 124,

C-O and C-X Bond Formation J. AM. CHEM. SOC. 2004, 126,

J. AM. CHEM. SOC. 2006, 128,

J. AM. CHEM. SOC. 2009, 131, 7520–7521

C-N Bond Formation Proposed Catalytic Cycle J. AM. CHEM. SOC. 2005, 127,

Domino Catalysis Involving Pd(IV) Catalysts J. AM. CHEM. SOC. 2007, 129,

Proposed Mechanism

First example of enantioselective palladium(IV) catalysis J. AM. CHEM. SOC. 2009, 131, 3452–3453

Problems 1.Little is known about the ligand effect of Pd(IV) complexes 2.Enantioselective synthesis using chiral ligands through Pd(IV) intermediates has not been forthcoming 3.Applications to natural product synthesis are lacking 4.Detailed mechanistic investigation

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. Conclusion