Homogeneous catalysis amination

We have investigated the arylation of different primary or secondary amines with different aryl chlorides or bromides in heterogeneous or homogeneous catalysis conditions using palladium(O) or palladium(II) derivatives (Fig. 5). 

Sequential hydroformylation/reductive amination of dendritic perallylated polyglycerols with various amines in a one-pot procedure to give dendritic polyamines in high yields (73-99%). Furthermore, the use of protected amines provides reactive core-shell-type architectures after deprotection. These soluble but membrane filterable multifunctional dendritic polyamines are of high interest as reagents in synthesis or as supports in homogeneous catalysis as well as nonviral vectors for DNA-transfection (Scheme 18) [65]. 

The nucleophilic attack by alkoxides, amines, and water is of great interest to homogeneous catalysis. A dominant reaction in syn-gas systems is the conversion of carbonyls with water to metal hydrides and carbon dioxide ("Shift Reaction"), see Figure 2.27. 

The catalytic asymmetric preparation of a-chiral amines, by addition of organo-metallic reagents to C=N bonds, is one of the most important reactions in homogeneous catalysis [26]. However, the catalytic asymmetric addition of simple alkylmetals has been achieved only in recent years. 

Rh and Ir complexes stabilized by tertiary (chiral) phosphorus ligands are the most active and the most versatile catalysts. Although standard hydrogenations of olefins, ketones and reductive aminations are best performed using heterogeneous catalysts (see above), homogeneous catalysis becomes the method of choice once selectivity is called for. An example is the chemoselective hydrogenation of a,/ -unsaturated aldehydes which is a severe test for the selectivity of catalysts. 

Gold(l) complexes of alkenes and alkynes appear to play an important role as intermediates of the gold(l)-catalyzed addition of water, alcohols, carboxylic acids, or amines to these substrates. The elfect of this 7r-complexation (22) is superior to the performance of mercury(ll) in this type of reactions. " In a similar way, gold(III) salts have found applications in homogeneous catalysis. ... 

For reviews of nucleophilic catalysis, see Bender, M.L. Mechanisms of Homogeneous Catalysis from Protons to Proteins, Wiley, NY, 1971, pp. 147-179 Jencks, W.P. Catalysis in Chemistry and Enzymology, McGraw-Hill, NY, 1969, pp. 61-11 Johnson, S.L. Adv. Phys. Org. Chem. 1967, 5, p. 271. For a review where 7. — 2l tertiary amine (the most common case), see Cherkasova, E.M. Bogatkov, S.V. Golovina,... 

Are heterogeneous catalysts appropriate platforms to construct cooperativity Cooperative catalysis can occm in homogeneous catalysis. For example, Kanemasa and Ito [3] have reported a two-catalyst system that leads to the dual activation of an electrophile and a nucleophile by a Lewis acid and amine base, respectively. 

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). 

Catalytic activity of rare earth elements (i.e., lanthanides, symbol Ln) in homogeneous catalysis was mentioned as early as 1922 when CeCls was tested as a true catalyst for the preparation of diethylacetal from ethanol and acetaldehyde [1]. Solutions of inorganic Ln salts were subsequently reported to catalyze the hydrolysis of carbon and phosphorous acid esters [2], the decarboxylation of acids [3], and the formation of 4-substituted 2,6-dimethylpyrimidines from acetonitrile and secondary amines [4]. In the meantime, the efficiency of rare earth metals in heterogeneous catalysis, e. g., as promoters in lanthanide (element mixtures)-... 

Since, in homogeneous catalysis, the chemical nature of the amine moiety has a large influence on the hydrolysis rate [2,6,7], the previous conditions with zeolites were applied to several aromatic amides containing different substituents and to benzanilide. 

In fat chemistry ( oleochemistry ) no considerable application of homogeneous catalysis and of industrial importance is known so far [1], One reason for this is the modest reactivity of the starting chemicals. Oleochemicals are molecules with a long carbon chain. The double bonds of unsaturated fatty compounds are always in internal positions. Hence, the steric hindrance of oleochemicals is often very high, and the coordination to metal complexes is made difficult. In addition all fatty compounds contain a substituent with a heteroatom such as carboxyl, ester, aldehyde, alcohol, or amine groups. These substituents often react with organome-tallic compounds and can inactivate the catalyst. 

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