Catalysis coinage metal

Scheme 12.11. Highly substituted furan heterocycles by coinage metal catalysis.

The transformation of an electrophilic carbonyl group to a nucleophilic enamine group with the help of a secondary amine was also applied in coinage metal catalysis.34 The reaction often, in much the same way as do other enamine catalyses, requires quite high catalyst loadings of the secondary amine. A test substrate for catalyst optimization was the malonate shown in Scheme 12.17. 

Most of the investigations in the area of coinage metal catalysis only provide data that do not allow a sound comparison of the catalytic activity or selectivity of the different metal complexes. In an often random manner, not only the metal but also the counterions and/or ligands and/or solvents are changed, and perhaps the reaction temperature as well. One gets the impression that the complexes that were at hand were the ones to be tested, not the ones that scientifically make sense at that point of the investigation. 

Modern Applications of Trispyrazolylborate Ligands in Coinage Metal Catalysis... 

Combined coinage metal catalysis for the synthesis of bioactive molecules 12JOM1. 

The best-known metals for SERS are the coinage metals, Cu, Ag, and Au, but SERS has been observed on many other metals. The relative size of the enhancements for different metals depends on the wavelength-dependent optical properties of the metal [38]. In the visible region enhancements are strong on Cu, Au, and particularly Ag because of the optical properties of those metals. For other metals the effect is much less. Nevertheless there have been considerable efforts to extend the apphcation of SERS to other metals, such as Pt, Pd, Rh, Ru, Fe, Co, Ni, etc., because of their importance in catalysis and electrochemistry [19, 39]. 

Comparatively, NHC-Ag complexes have found less application in catalysis so far, although their synthetic potential has been eonfirmed by several recent reports. Their sporadic appearance in the literature as eatalysts confirms that they can advantageously replace other coinage metal based catalysts in a series of transformations. 

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