Hydroamination metal catalysis

Intramolecular addition of amine N-H bonds to carbon-carbon multiple bonds would afford nitrogen heterocycles. To realize catalytic cyclization of a,co-aminoalkenes or aminoalkynes, various catalytic systems have been developed especially with early transition metals such as titanium, zirconium, lanthanide metals, and actinide metals [ 12], Late-transition-metal catalysis based on Ni, Pd, and Rh has also proved to be efficient [ 12], Recently, the ruthenium-catalyzed intramolecular hydroamination of aminoalkynes 15 was reported to afford 5-7-membered ring products 16 in various yields (Eq. 6) [13]. Among... 

Abstract This chapter describes late transition metal complexes-catalyzed hydroamination, the formal additimi of an H-N bond across a C-C multiple bond. Late transition metal catalysis has been intensely developed in the hydroamination and additions of various kinds of amines to C-C multiple bonds have been achieved. The reaction pathways strrMigly depend on the choice of metal complexes, substrates, and reaction conditions. This chapter is organized primarily based on the difference in the mechanisms of hydroamination reactions, and in the scope section concise summary of the hydroamination reaction is shown. 

Taube, R. Reaction with Nitrogen Compounds Hydroamination. In Applied Homogeneous Catalysis with Organo-metallic Compounds Comils, B. Herrmann, W. A., Eds. VCH Weinheim, Germany, 1996 pp 507-520. 

A high-throughput colorimetric assay was applied to identify catalysts by combining metals (Pd, Rh, Ru, Ir) and various phosphines for the hydroamination of dienes.217 Combinatorial catalysis was successfully used to find active catalysts in the Ru-catalyzed ring-closing metathesis reaction218 and the olefin polymerization by Ni and Pd.219... 

To catalyze the direct hydroamination of olefins according to eq. (1) two basic approaches have been employed involving primarily the activation either of the amine or of the olefin. One possible way to activate the amine for catalysis is the transformation to the much stronger nucleophilic amide ion by deprotonation. Thus, the amides of strongly electropositive metals, such as alkali metals, alkaline earth metals, or lanthanides, are able to react with the C-C double bond under... 

As the first transition metal-based homogeneous catalysis of hydroamination, in the early 1970s Coulson from the Du Pont laboratories had described the addition of secondary aliphatic amines to ethylene in the presence of various rhodium compounds [15, 16]. Definite results were reported with RhCl3 3 H2O as pre-catalyst in tetrahydrofuran as solvent under starting ethylene pressures of 5-14 MPa at 180-200 °C for different secondary amines (Table 3). 

Abstract This review deals with the synthesis and the catalytic application of noncyclopentadienyl complexes of the rare-earth elements. The main topics of the review are amido metal complexes with chelating bidentate ligands, which show the most similarities to cyclopentadienyl ligands. Benzamidinates and guanidinates will be reviewed in a separate contribution within this book. Beside the synthesis of the complexes, the broad potential of these compounds in homogeneous catalysis is demonstrated. Most of the reviewed catalytic transformations are either C-C multiple bond transformation such as the hydroamination and hydrosilylation or polymerization reaction of polar and nonpolar monomers. In this area, butadiene and isoprene, ethylene, as well as lactides and lactones were mostly used as monomers. 

In 2003, O Shaughnessy and Scott reported the first example of rare-earth metal complexes supported by biaryl diamide ligands as the catalysts for the hydroamination reactions [159]. A series of C2 symmetric secondary diamine proligands L37-L40 were prepared by arylations of (7 )-2,2 -diamino-6,6 -dimethybiphenyl under palladium catalysis. L37 reacted with complexes [Ln N(SiHMe2)2 3(THF)2] to form the biaryl diamide complexes [Ln(L37) N(SiHMe2)2 (THF)2] (Ln = Y (190), La (191), Sm (192)). Deprotonation... 

Within the past 10 years, several classes of postmetallocenes of the lanthanides, especially the monoanionic amido metal complexes, were developed as homogeneous catalysts. These compounds were basically used in two fields, C-C multibond transformations and the polymerization catalysis. In the area of multibond transformations, the hydroamination and the hydrosilylation reaction were most intensely... 

During the last two decades, lanthanide catalysis has been extensively explored [3], considering the unique properties and the absence of toxicity of these "heavy" metals which make them environmentally friendly. Olefin transformations catalysed by organolanthanides such as oligomerisation, hydrogenation, hydrosilylation, hydroamination, polymerisation, have attracted much attention. The two latter reactions can be initiated by hydrides (which act as precatalysts, such as for MMA polymerisation [4]), but do not involve hydrides as intermediates in the catalytic cycle and therefore will not be considered in the present review. 

While ethylene hydroamination with secondary amines was reported by Coulson using Rh as a catalyst in 1971 [86], unfortunately, despite decades of research in the area, there are no catalysts for this reaction across a broad range of substrates. Significant early work in d-block-metal-hydroamination catalysis took advantage of the controlled reactivity provided by mercurial salts. However, the toxicity and ensuing environmental problems of using Hg " " salts demanded an improvement in catalytic protocols. Indeed, steady advancement in the application... 

Most importantly, this reaction demands control of regioselectivity and can also be carried out asymmetrically (Scheme 15.38). Thus, branched imine or linear allylamine products can be selectively prepared. Diastereoselective and enantiose-lective allene hydroamination can also be targeted with advances in enantioselective catalysis using late transition metals being reviewed in Section 15.3.7. 

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