Organic electrophile

In this chapter, we w ill emphasize tliese recent developments, especially tliose tliat allow tlie preparadoti of orgatiocoppet species not accessible tlitougb tlie statidard procedures involving otganolitliiunis as precursors and their use in reactions with organic electrophiles. 

The late Professor J. K. Stille pioneered the development of a very effective and versatile palladium-mediated C-C bond forming method - the palladium-catalyzed cross-coupling of organic electrophiles with organostannanes.48 This process continues to enjoy much success in organic synthesis because it proceeds in high yields under mild reaction conditions and because it tolerates a... 

In the direct coupling reaction (Scheme 30), it is presumed that a coordinatively unsaturated 14-electron palladium(o) complex such as bis(triphenylphosphine)palladium(o) serves as the catalytically active species. An oxidative addition of the organic electrophile, RX, to the palladium catalyst generates a 16-electron palladium(n) complex A, which then participates in a transmetalation with the organotin reagent (see A—>B). After facile trans- cis isomerization (see B— C), a reductive elimination releases the primary organic product D and regenerates the catalytically active palladium ) complex. 

The zirconium TMM complexes also react with organic electrophiles, including unactivated ones, according to Scheme 99 under formation of the corresponding substituted allyl complexes. ... 

Transition metal catalysed cross-coupling reactions of organometalUc reagents containing Zn, Si, Mg, Sn or B with organic electrophiles in the presence of group 8-10 metals, notably Ni and Pd, are routinely the method of choice, both in academia and industry, for the preparation of C-0, C-S, C-H, C-N and C-C bonds [1]. 

Cross-coupling reactions resulting in C-C bond formation are normally classified according to the nature of the organometallic reagent and the organic electrophile. Scheme 6.4 summarises, broadly, the names and reaction partners of the most common of these transformations. 

The Suzuki-Miyaura reaction, first reported by Suzuki and co-workers in 1979 [87], is the metal-mediated (often palladium) coupling of organic electrophiles such as alkenyl... 

Omary M.A., Mohamed, A.A., Rawashdeh-Omary, M.A. and Fackler, J.P. Jr (2005) Photophysics of supramolecular binary stacks consisting of electron-rich trinuclear Au(I) complexes and organic electrophiles. Coordination Chemistry Reviews, 249, 1372-1381. 

Hydroboration of alkenes or alkynes followed by cross-coupling with organic electrophiles provides a straightforward method for the carbon-carbon bond formation (Scheme 1-19). The hydroboration of thioalkynes with catecholborane in the presence of a nickel or palladium catalyst yields P-(aLkylthio)-l-alkenylboronates (72a)... 

In the Stille reaction, an organotin compound R1SnR3 and an organic electrophile R2X are treated with a palladium(O) or palladium(ll) catalyst, to generate the coupled product R R2 (Equation (55)).190... 

The coupling of organosilicon compounds with organic electrophiles was not disclosed until 1988 by Hatanaka and Hiyama, when they demonstrated that through the addition of an appropriate silicophilic nucleophile, those desired pentacoordinate species can be generated in situ and transfer an unsaturated group. Nucleophilic fluoride sources were found to be the additive of choice, typically TASK, TBAF, and, in some cases, KF and GsF. These are the fundamental concepts of what is nowadays called the Hiyama reaction. The use of fluoride... 

Three-component reactions between organic electrophile (halide, ester, etc.), carbon monooxide, and organic nucleophile (organometallic compound) (Equation (1)) catalyzed by transition metal complexes afford a powerful method for the synthesis of various ketones. The pioneering works in this area appeared in the early 1980s. 

These reactions are divided into two sections. In the former, representative examples of organic electrophiles, which can be used in reactions with magnesium ketone enolates, are summarized. The second section shows that magnesium ketone enolates can be employed as interesting alternatives to their more known lithium counterparts in aldol addition reactions. This part is discussed in terms of regio- and stereoselectivity. 

For reviews of the Pd-catalyzed acylation and other cross-coupling reactions with a-hetero-substituted organic electrophiles, see ... 

Stille, J. K. The Palladium-Catalysed Cross-Coupling Reactions of Organo-tin Reagents with Organic Electrophiles, Angew. Chem. Int. Ed. Engl. 1986, 25, 508-524. 

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