Palladium(0) Complexes with Unsymmetric Bidentate Nitrogen Ligands for the Stereoselective Hydrogenation of 1-Phenyl-1-propyne to ( Z )-1-Phenyl-1-propene
2002; American Chemical Society; Volume: 21; Issue: 8 Linguagem: Inglês
10.1021/om0108346
ISSN1520-6041
AutoresMartijn W. van Laren, Marcel A. Duin, C. A. de Klerk, Michele Naglia, Dominga Rogolino, Paolo Pelagatti, Alessia Bacchi, Corrado Pelizzi, Cornelis J. Elsevier,
Tópico(s)Catalytic C–H Functionalization Methods
ResumoA series of zerovalent palladium complexes Pd(NN)(alkene) of bi- or tridentate nitrogen ligands of the general formula 6-R' '-C5H3N-(C(R')NR)-2 (R' ' = H, Me, CHNR'; R' = H, Me; R = alkyl, aryl, or amino group) and dimethylfumarate (dmfu) have been prepared and were subsequently employed as precatalysts in the homogeneous stereoselective semihydrogenation of 1-phenyl-1-propyne. An X-ray structure of Pd(C5H4N-(C(Me)Ni-Pr)-2)(dmfu) was obtained. Whereas only relative small changes in substituents apply, the various complexes show very different stabilities under hydrogenation conditions. The complex Pd(C5H4N-(C(H)N(CH2)2OH)-2)(dmfu) exhibits a good selectivity for the (Z)-alkene but decomposes just before full conversion of the alkyne, whereas the complex Pd(C5H4N-(C(H)Ni-Pr)-2)(dmfu) exhibits a good selectivity and stability under hydrogenation conditions and is a suitable catalyst for the stereoselective hydrogenation of 1-phenyl-1-propyne to (Z)-1-phenyl-1-propene.
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