Palladium(II) Complexes of Chiral 1,2-Diiminophosphoranes: Synthesis, Structural Characterization, and Catalytic Activity for the Allylic Alkylation
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- 作者：Mathieu Sauthier ; Jorge Fornié ; s-Cá ; mer ; Loï ; c Toupet ; and Ré ; gis Ré ; au
- 刊名：Organometallics
- 出版年：2000
- 出版时间：February 21, 2000
- 年：2000
- 卷：19
- 期：4
- 页码：553 - 562
- 全文大小：233K
- 年卷期：v.19,no.4(February 21, 2000)
- ISSN：1520-6041
文摘
Chiral 1,2-bis[tris(dimethylamino)phosphinimino]cyclohexane (7a, 80% yield), 1,2-bis[tris(dimethylamino)phosphinimino]-1,2-diphenylethane (7b, 74% yield), 1,2-bis[triphenoxyphosphinimino]cyclohexane (9a, 85% yield), and 1,2-bis[triphenoxyphosphinimino]-1,2-diphenylethane (9b, 70% yield) have been prepared using (1R,2R)-1,2-diaminocyclohexane or(1R,2R)-1,2-diphenylethylenediamine and the corresponding phosphine dibromide derivatives(the Kirsanov route). 1,2-Bis[triphenylphosphinimino]cyclohexane (2), 1,2-bis[triphenylphosphinimino]-1,2-diphenylethane (3), and 1,2-diiminophosphoranes 7b and 9b reacted with[Pd(
3-C3H5)Cl]2 in the presence of a silver salt in CH2Cl2 at room temperature to afford thecationic complexes 10 (81% yield), 11 (84% yields), 15 (78% yield), and 16 (74% yield),respectively. According to the same general procedure, palladium complexes [(3-PhCHCHCHPh)(2)Pd]TfO (13, 88% yield) and [(3-PhCHCHCHPh)(3)Pd]TfO (14, 86% yield)have been prepared. Single-crystal X-ray diffraction studies of derivatives 10, 11, and 13have been carried out. They revealed that C2 symmetry was retained for derivative 3 uponcoordination, but lost for 2 in the coordination sphere of the metal. 13C NMR chemical shiftsfor the terminal C atoms of the allyl moiety of these complexes indicate that the donor abilityof 1,2-diiminophosphoranes varies with the nature of the P-substituents and is comparableto that of other sp2-hybridized nitrogen ligands. 1,2-Diiminophosphoranes were evaluatedas ligands for the Pd-catalyzed enantioselective allylic substitution reaction of rac-1,3-diphenylprop-2-enyl acetate with the anion of dimethyl malonate. Ligands 3 and 7a,b inducegood catalytic activities compared with other N,N-ligands but moderate ee's (10-77%) at36 
C. Higher ee's (85%) were obtained at room temperature with ligand 3 but at the expenseof the catalytic activity. This study revealed that 1,2-diimonophosphoranes are able tostabilize Pd(0) species during a catalytic process and to induce notable levels of enantioselectivity.
3-C3H5)Cl]2 in the presence of a silver salt in CH2Cl2 at room temperature to afford thecationic complexes 10 (81% yield), 11 (84% yields), 15 (78% yield), and 16 (74% yield),respectively. According to the same general procedure, palladium complexes [(3-PhCHCHCHPh)(2)Pd]TfO (13, 88% yield) and [(3-PhCHCHCHPh)(3)Pd]TfO (14, 86% yield)have been prepared. Single-crystal X-ray diffraction studies of derivatives 10, 11, and 13have been carried out. They revealed that C2 symmetry was retained for derivative 3 uponcoordination, but lost for 2 in the coordination sphere of the metal. 13C NMR chemical shiftsfor the terminal C atoms of the allyl moiety of these complexes indicate that the donor abilityof 1,2-diiminophosphoranes varies with the nature of the P-substituents and is comparableto that of other sp2-hybridized nitrogen ligands. 1,2-Diiminophosphoranes were evaluatedas ligands for the Pd-catalyzed enantioselective allylic substitution reaction of rac-1,3-diphenylprop-2-enyl acetate with the anion of dimethyl malonate. Ligands 3 and 7a,b inducegood catalytic activities compared with other N,N-ligands but moderate ee's (10-77%) at36 C. Higher ee's (85%) were obtained at room temperature with ligand 3 but at the expenseof the catalytic activity. This study revealed that 1,2-diimonophosphoranes are able tostabilize Pd(0) species during a catalytic process and to induce notable levels of enantioselectivity.