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

Echavarren, Antonio M.; Crdenas, Diego J.

doi:10.1002/9783527619535.ch1

Cited by 28 publications

(15 citation statements)

References 345 publications

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“…The general reaction mechanism has been shown to involve typical steps for cross-coupling [98,113]. Oxidative addition of an aryl halide generates a Pd(II) species that undergoes transmetalation to form a Pd(II)-thiolate.…”

Section: Equationmentioning

confidence: 99%

Organometallic Approaches to Carbon–Sulfur Bond Formation

2010

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Section: Equationmentioning

confidence: 99%

Organometallic Approaches to Carbon–Sulfur Bond Formation

2010

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“…The palladium-catalyzed cross-coupling reactions of various organometallic donors involve three elementary steps: (1) oxidative addition the transition metal catalyst to the halide or pseudohalide, (2) transmetalation of the organometallic reagent to provide a diorganopalladium(II) complex and (3) reductive elimination of the diorganopalladium(II) complex to form the product with regeneration of the palladium(0) catalyst 13. Of the three elementary steps, the transmetalation remains the most controversial and likely depends upon the organometallic donor 14…”

Section: Kinetic Analysis and Mechanistic Implicationsmentioning

confidence: 99%

Palladium-Catalyzed Cross-Coupling Reactions of Organosilanols and Their Salts: Practical Alternatives to Boron- and Tin-Based Methods

2008

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ConspectusIn the panoply of modern synthetic methods for forming carbon-carbon and carbon-heteroatom bonds, the transition metal-catalyzed cross coupling of organometallic nucleophiles with organic electrophiles enjoys a preeminent status. The preparative utility of these reactions is, in large measure, a consequence of the wide variety of organometallic donors that have been conscripted into service. The most common of these reagents are organic derivatives of tin, boron, and zinc, which each possess unique advantages and shortcomings. Because of their low cost, low toxicity, and high chemical stability, organosilanes have emerged as viable alternatives to the conventional reagents in recent years. However, unlike the tin-and zinc-based reactions that require no activation or the boron-based reactions that require only heating with mild bases, silicon-based cross-coupling reactions often require heating in the presence of a fluoride source; this has significantly hampered the widespread acceptance of organosilanes.To address the "fluoride problem", we have introduced a new paradigm for palladium-catalyzed, silicon-based cross-coupling reactions that employs organosilanols, a previously underutilized class of silicon reagents. The use of organosilanols either in the presence of Brønsted bases or as their silanolate salts represents a simple and mild alternative to the classic fluoride-based activation method. Organosilanols are easily available by many well-established methods for introducing carbon-silicon bonds onto alkenes, alkynes and arenes, and heteroarenes. Moreover, we have developed four different protocols for the generation of alkali metal salts of, vinyl-, alkenyl-, alkynyl-, aryl-, and heteroarylsilanolates: (1) reversible deprotonation with weak Brønsted bases, (2) irreversible deprotonation with strong Brønsted bases, (3) isolation of the salts from irreversible deprotonation, and (4) silanolate exchange with disiloxanes. We have demonstrated the advantages of each of these methods for a number of different coupling classes.The defining feature of this new process is the formation of a covalently linked palladium silanolate species that facilitates the critical transmetalation step. We have verified the intermediacy of a critical species that contains the key Si-O-Pd linkage by its identification as the resting state in reaction mixtures, by X-ray analysis, and by demonstrating its competence in thermal cross-coupling with no * Address Correspondence to: Professor Scott E. Denmark, 245 Roger Adams Laboratory, Box 18, Department of Chemistry, University of Illinois, 600 S. Mathews Avenue, Urbana, IL 61801, phone: (217) 333-0066, fax: (217) 333-3984, email: denmark@scs.uiuc "...Work in this field (silicon-based cross-coupling) has been quite active since the initial disclosure of siletane cross-coupling from these laboratories... Future studies are focused on several fronts, including the extension of scope to incorporate less reactive substrates such as chlorides and triflates, further optimiza...

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“…Nickel(II) complexes have received high attention as (pre)catalysts in the field of transition metal catalyzed C-C cross-coupling reactions [14][15][16][17][18][19][20][21][22][23][24][25][26][27]. This area has been dominated by palladium catalysts in the last 20 years, which became manifest in the 2010 Nobel prize for R. Heck, E. Negishi, and A. Suzuki [28,29].…”

Section: Introductionmentioning

confidence: 99%

“…Although many C-C cross-coupling reactions can be catalyzed by palladium and nickel compounds, there are often large mechanistic differences between the two metals under similar reaction conditions. Palladium catalysts normally shuttle between two of the three even electron oxidation states (0, +II, and +IV) during C-C coupling reactions, and two-electron processes such as oxidative addition and reductive elimination are common mechanistic steps [14,15,24,25]. For nickel, single electron pathways between the oxidation states (0, +I, +II, +III, and +IV) often occur in addition to oxidative addition and reductive elimination [24][25][26]31,32].…”

Section: Introductionmentioning

confidence: 99%

Exploring Mechanisms in Ni Terpyridine Catalyzed C–C Cross-Coupling Reactions—A Review

2018

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Abstract:In recent years, nickel has entered the stage for catalyzed C-C cross-coupling reactions, replacing expensive palladium, and in some cases enabling the use of new substrate classes. Polypyridine ligands have played an important role in this development, and the prototypical tridentate 2,2 :6 ,2 -terpyridine (tpy) stands as an excellent example of these ligands. This review summarizes research that has been devoted to exploring the mechanistic details in catalyzed C-C cross-coupling reactions using tpy-based nickel systems.

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

Cited by 28 publications

References 345 publications

Organometallic Approaches to Carbon–Sulfur Bond Formation

Organometallic Approaches to Carbon–Sulfur Bond Formation

Palladium-Catalyzed Cross-Coupling Reactions of Organosilanols and Their Salts: Practical Alternatives to Boron- and Tin-Based Methods

Exploring Mechanisms in Ni Terpyridine Catalyzed C–C Cross-Coupling Reactions—A Review

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