Multiple metal-carbon bonds catalysis

The discovery of multiple metal-carbon BONDS AND THE GOLDEN AGE OF CATALYSIS... 

The aim of this volume is to convince the reader that metal carbene complexes have made their way from organometallic curiosities to valuable - and in part unique - reagents for application in synthesis and catalysis. But it is for sure that this development over 4 decades is not the end of the story there is both a need and considerable potential for functional organometallics such as metal carbon multiple bond species which further offer exciting perspectives in selective synthesis and catalysis as well as in reactions applied to natural products and complex molecules required for chemical architectures and material science. 

It is likely that more silicon-carbon bonds are produced by the hydrosilylation of olefins than by any other method except the direct process. This deceptively simple addition of an Si-H bond to a C-C multiple bond can be promoted by a variety of means, but transition metal catalysis is by far the most significant. Two relatively old catalysts, H2PtCl6 ( Speier s catalyst ) and Pt2(Me2ViSiOSiMe2Vi)3 ( Karstedt s catalyst ), remain the most effective, and the remarkable rates and turnover numbers observed in these systems are among the most impressive in all of organometallic chemistry. The bulk of the literature on hydrosilylation falls outside the scope of this review, and readers are directed to the comprehensive work on hydrosilylation edited by Marciniec.93... 

There is relevant material on carbenes in reviews on catalytic methods for metal carbene transformations formation of metal carbon multiple bonds from alkynes, metathesis catalysis. ... 

Transition metal NPs dispersed in ILs are recognized as suitable catalyst systems for many reaction types with both typical homogeneous and heterogeneous catalysis (see Sections 1.3.1-1.3.5). The most investigated reactions are the hydrogenation of multiple bonds and arenes [1, 5, 12, 13, 43, 44, 54, 80, 89, 92], carbon-carbon cross-... 

The entries into transition metal catalysis discussed so far, required the presence of a specific bond (a polar carbon-heteroatom bond for oxidative addition or a carbon-carbon multiple bond for coordination-addition processes) that was sacrificed during the process. If we were able to use selected carbon-hydrogen bonds as sacrificial bonds, then we could not only save a lot of trouble in the preparation of starting materials but we would also provide environmentally benign alternatives to several existing processes. In spite of the progress made in this field the number of such transformations is still scarce compared to the aforementioned reactions. 

Aziridines can add to carbon—carbon multiple bonds. Elevated temperature and alkali metal catalysis are required in the case of nonpolarized double bonds (193—195). On the other hand, the addition of aziridines onto the conjugated polarized double or triple bonds of a,p-unsaturated nitriles (196—199), ketones (197,200), esters (201—205), amides (197), sulfones (206—209), or quinones (210—212) in a Michael addition-type reaction frequendy proceeds even at room temperature without a catalyst. The adducts obtained from the reaction of aziridines with a,p-unsaturated ketones, eg, 4-aziridinyl-2-butanone [503-12-8] from 3-buten-2-one, can be converted to 1,3-substituted pyrrolidines by subsequent ring opening with acyl chlorides and alkaline cyclization (213). 

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... 

Alkene metathesis catalysis involves intermediates in which a transition metal is multiply bonded to carbon. These species are often referred to as nucleophilic caibenes when the carbon atom is negatively polarized. A more functional description is to name these compounds as alkylidene complexes, since they react to transfer an alkylidene moiety from a transition metid to a substrate carbon atom. Previous sections of this chapter have focused on a common example of this chemistry the process of metathesis that involves transition metal mediated interaction of carbon-carbon multiple bonds. 

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