Isocyanide Insertion into the Palladium−Carbon Bond of Complexes Containing Bidentate Nitrogen Ligands:  A Structural and Mechanistic Study

Abstract

Isocyanide insertion into the palladium-carbon bond of complexes containing bidentate nitrogen ligands; A structural and mechanistic study Delis, J.G.P.; Aubel, P.G.; Vrieze, K.; van Leeuwen, P.W.N.M.; Veldman, N.; Spek, A.L.; van Neer, F.J.R. Published in: Organometallics DOI:10.1021/om970096eLink to publication Citation for published version (APA):Delis, J. G. P., Aubel, P. G., Vrieze, K., van Leeuwen, P. W. N. M., Veldman, N., Spek, A. L., & van Neer, F. J. R. (1997). Isocyanide insertion into the palladium-carbon bond of complexes containing bidentate nitrogen ligands; A structural and mechanistic study. Organometallics, 16, 2948-2957. DOI: 10.1021/om970096e General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Insertion of the isocyanides 2,6-dimethylphenyl isocyanide (DIC), tert-butyl isocyanide (TIC) and tosylmethyl isocyanide (TosMIC) into the Pd-Me bond of complexes (NkN)Pd(Me)Cl (NkN ) 2,2′-bipyridine (bpy), 1,10-phenanthroline (phen), 2,2′-bipyrimidine (bpm)) afforded quantitatively (NkN)Pd(C(dNsR)Me)Cl (R ) 2,6-Me 2 C 6 H 3 , t-Bu, CH 2 Tosyl). The course of the reaction has been shown to proceed via the intermediates [(NkN)Pd(CN-R)(Me)]Cl (NkN ) bpy, phen; R ) 2,6-Me 2 C 6 H 3 , t-Bu, CH 2 Tosyl), which have been characterized at 250 K by NMR and IR spectroscopies and conductivity measurements. The mechanism of the insertion reaction involves substitution of the halide by the isocyanide followed by a rate-determining methyl migration to the precoordinated isocyanide. Kinetic measurements of the isocyanide insertion reaction, which provided the reaction rate constants of the isocyanide association (k 1 ), isocyanide dissociation (k -1 ), and methyl migration reaction (k 2 ), have demonstrated that the migration rate of the methyl group to the precoordinated isocyanide increases with increasing electrophilicity of the isocyanide. Methyl migration in the intermediate complexes [(NkN)Pd(CN-R)(Me)]Cl (NkN ) bpy, phen; R ) 2,6-Me 2 C 6 H 3 , t-Bu, CH 2 Tosyl) also occurs in the solid state. The complexes (NkN)Pd(C(dNsR)Me)X (NkN ) bpy, phen; R ) t-Bu, CH 2 Tosyl; X ) Cl, Br) show a fluxional behavior due to a site exchange of the nitrogen donor atoms. Spin saturation transfer 1 H NMR experiments showed that the mechanism of this process involves Pd-N bond breaki...

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“…Addition of four equivalents of tert ‐butyl isocyanide ( t BuNC) to (fc P,B )PdMe resulted in the isolation of (fc P,B )Pd[C(Me)N t Bu](CN t Bu) · (C 7 H 8 ) as an orange crystalline material; see Equation . The new compound is the product of a migratory insertion of one equivalent of t BuNC into the palladium–carbon bond and the coordination of a second equivalent of t BuNC to the palladium metal center , . The two pyrazoles are not chemically equivalent in the 1 H NMR spectrum (Figure ), suggesting that only one of them is coordinated to palladium.…”

Does levator ani injury affect cystocele type?

“…Finally, we further extended our horizons from organic chemistry to organometallics by the insertion of isocyanides into palladium–carbon bonds in good yield (Figure S4 and Method S10) 18. 19…”

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“…Finally, we further extended our horizons from organic chemistry to organometallics by the insertion of isocyanides into palladium-carbon bonds in good yield ( Figure S4 and Method S10). [18,19] The ability of the system to arrive at the desired conversion in minutes rather than the hours that are usually needed in a conventional batch system, and its capability to deliver much higher yields in spite of these short reaction times, illustrate the power of the microfluidic system when it is combined with multicomponent reactions. Enhanced mass and heat transfer in the microreactor allowed a reduction in reaction time while avoiding the formation of side products, which is one of the drawbacks with a wide range of multicomponent reactions.…”