Transition-metal molecules, methodological

Another important aspect of aryne chemistry that has found application in benzo-fused heterocycles synthesis is MCRs, which generally include the first addition of nucleophiles to arynes and subsequent interception of the aryl anion intermediate with other electrophiles. If the nucleophile and electrophile are not part of the same molecule, the overall process is a unique multicomponent coupling, where the aryne is inserted between the other two coupling partners to afford the final product 85 (Scheme 39). This highly efficient transition-metal-free methodology has been applied to the S5mthesis of valuable benzo-fused heterocycles and has foxmd application in natural product synthesis. 

The l ,J -DBFOX/Ph-transition metal aqua complex catalysts should be suitable for the further applications to conjugate addition reactions of carbon nucleophiles [90-92]. What we challenged is the double activation method as a new methodology of catalyzed asymmetric reactions. Therein donor and acceptor molecules are both activated by achiral Lewis amines and chiral Lewis acids, respectively the chiral Lewis acid catalysts used in this reaction are J ,J -DBFOX/Ph-transition metal aqua complexes. 

The underlying motivation of the work presented in this paper is to provide a theoretical understanding of basic physical and chemical properties and processes of relevance in photoelectrochemical devices based on nanostructured transition metal oxides. In this context, fundamental problems concerning the binding of adsorbed molecules to complex surfaces, electron transfer between adsorbate and solid, effects of intercalated ions and defects on electronic and geometric structure, etc., must be addressed, as well as methodological aspects, such as efficiency and reliability of different computational schemes, cluster models versus periodic ones, etc.. 

Initial reports on the borylation of alkanes using isolated transition-metal-boryl complexes date back to 1995, when Hartwig showed that Cp Re(CO)2(Bpin)2 converts pentane to 1-borylpentane with high regioselectivity. " The catalytic C-H borylation of alkanes with Cp Re(CO)3 using photochemical activation was demonstrated soon thereafter (equation 25). Also, an efficient thermal process that involves the use of rhodium catalysts has since been developed (equation 26). It is interesting to note that this methodology is not restricted to small molecules, but has recently been exploited for the direct side-chain functionalization of polyolefins. ... 

Chapter 12 serves as an introduction to a huge area of chemistry devoted to the use of organometallic compounds for the construction of complex molecules. The material covered in Chapter 12 exemplifies several of the most important applications of organotransition metal chemistry to organic synthesis. Thousands of articles have appeared over the past 10 years that report on either the use of transition metal compounds in key steps of syntheses, which would be difficult or even impossible to carry out without transition metals, or on the development of novel methodology that may have many applications to synthesis down the road. Research on the connection between organometallic chemistry and synthesis remains active and fruitful, and there is every indication that this endeavor will continue to hold the interest of chemists for many years to come. 

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