C-X bond forming reactions

The use of enzymes to catalyze reversible reactions has proven to be an effective strategy for DCC. Enzymes work under physiological conditions (by definition), are reversible, and can also be applied to a variety of C-C and C-X bond-forming reactions. Venton and coworkers reported the first example of an enzyme-catalyzed process being used in a DCC context [32]. As their work preceded the codification of DCC in the literature, it contains little of the vocabulary that has come to define the field. It does, however, correspond perfectly with the conceptual framework of DCC, and has been widely cited as an influential early example of the DCC idea. 

Scheme 3 Reaction sites of organobismuth(V) reagents in C-C and C-X bond forming reactions (a) alkenylbismuthonium salt (b) alkynylbismuthonium salt (c) bismuth ylide (d) bismuth imide. Nu nucleophile, B base, El electrophile...

First developments in the Friedel-Crafts alkylation were concentrated on the use of stoichiometric amounts of Lewis acids, such as A1C13, BF3 or TiCl4, to produce stoichiometric amounts of salt by-products [5-9]. However, in recent years more and more catalytic methods have been developed. In particular, rare earth metal triflates, including Sc(OTf)3, La(OTf)3 and Yb(OTf)3, have been extensively used as Lewis acid catalysts in various C-C and C-X bond forming reactions [10-13], Despite the benefit of their versatility for organic synthesis, these Lewis acids possess major drawbacks. They are expensive, rather toxic [14], and air- and moisture-sensitive. 

Echavarren AM, Cardenas DJ (2004) Mechanistic aspects of metal-catalyzed C,C-and C,X-bond-forming reactions. In De Meijere A, Diederich F (eds) Metal-catalyzed cross-coupling reactions. Wiley-VCH, Weinheim, p 1... 

This chapter has presented the current stage in the development of metal-promoted asymmetric C—C and C—X bond forming reactions, in which cinchona alkaloids are utilized as chirality inducers. As shown in many of the examples discussed above, cinchona alkaloids and their derivatives have great potential to serve as chiral ligands or cobase catalysts in diverse metal-promoted asymmetric C—C and C—X bond forming reactions. However, despite the scientific achievements that have been made... 

The second strategy involves the generation of the Pd intermediate at the expense of an oxidant after the C—H bond activation. It leads to the development of C—C and C—X bond-forming reactions through Pd"/Pd redox catalysis. 

High valent oxo-molybdenum complexes as efficient catalysts for C—X bond forming reactions pC = C, N, O, S, P, Br, I, H) 12COC33. 

This chapter has surveyed a wide range of C—X bond-forming reactions, where X = C,0, N, S, and halogen. The enzymes that catalyse carbon-carbon bond formation are potentially the most useful and show some... 

A-Triflyl phosphoramides derived from BINOL are highly acidic chiral Brpnsted acids, and they are powerful catalysts for enantioselective C-C and C-X bond-forming reactions. Their design, structural features, and applications since their development in 2006 have been reviewed. 

Mechanistic Aspects of Metal-Catalyzed C,C- and C,X-Bond Forming Reactions... 

Copper has also been used to couple aryl halides with amines, alcohols, or thiols in the presence of a ligand [411, 412). Chelating N N, N O, and 0"0 ligands [413-421] are cracial in these C-X bond-forming reactions. 

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