One-Pot Negishi Cross-Coupling Reactions of In Situ Generated Zinc Reagents with Aryl Chlorides, Bromides, and Triflates

Sase, Shohei; Jaric, Milica; Metzger, Albrecht; Malakhov, Vladimir; Knöchel, Paul

doi:10.1021/jo801063c

Cited by 135 publications

(65 citation statements)

References 15 publications

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“…[8c, 9, 30,31] To facilitate the kinetic analysis, we employed the organozinc reagent in excess (4 equiv relative to ArI). During the reaction, its concentration could change by no more than 25 % (in the absence of decomposition reactions) such that approximately pseudofirst-order conditions were maintained.…”

Section: Model Systemmentioning

confidence: 99%

Catalyst Activation, Deactivation, and Degradation in Palladium‐Mediated Negishi Cross‐Coupling Reactions

Böck

Feil

Karaghiosoff

et al. 2015

Chemistry A European J

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Pd-mediated Negishi cross-coupling reactions were studied by a combination of kinetic measurements, electrospray-ionization (ESI) mass spectrometry, (31)P NMR and UV/Vis spectroscopy. The kinetic measurements point to a rate-determining oxidative addition. Surprisingly, this step seems to involve not only the Pd catalyst and the aryl halide substrate, but also the organozinc reagent. In this context, the ESI-mass spectrometric observation of heterobimetallic Pd-Zn complexes [L2 PdZnR](+) (L=S-PHOS, R=Bu, Ph, Bn) is particularly revealing. The inferred presence of these and related neutral complexes with a direct Pd-Zn interaction in solution explains how the organozinc reagent can modulate the reactivity of the Pd catalyst. Previous theoretical calculations by González-Pérez et al. (Organometallics- 2012, 31, 2053) suggest that the complexation by the organozinc reagent lowers the activity of the Pd catalyst. Presumably, a similar effect also causes the rate decrease observed upon addition of ZnBr2 . In contrast, added LiBr apparently counteracts the formation of Pd-Zn complexes and restores the high activity of the Pd catalyst. At longer reaction times, deactivation processes due to degradation of the S-PHOS ligand and aggregation of the Pd catalyst come into play, thus further contributing to the appreciable complexity of the title reaction.

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Section: Model Systemmentioning

confidence: 99%

Catalyst Activation, Deactivation, and Degradation in Palladium‐Mediated Negishi Cross‐Coupling Reactions

Böck

Feil

Karaghiosoff

et al. 2015

Chemistry A European J

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“…The traditional method of cross-coupling reactions provides powerful tools for the preparation of these organic compounds [3]. Cross-coupling reactions to biaryls, certainly carried out as C-H activations, do not depend on the preparation of halo aromatics, The reactions, such as Suzuki [4], Ullmann [5], Buchwald [6], Sonogashira [7], Kumada [8], Stille [9], Negishi [10], and Hiyama [11] crosscoupling reactions, have emerged as methods for the synthesis of both symmetrical and unsymmetrical diaryls from pseudohalides or aryl halides and organometallics. Ultimately, they offer remarkable effectiveness along with several drawbacks.…”

Section: Introductionmentioning

confidence: 99%

Synthetic journey towards transition metal-free arylations

Roopan

Palaniraja

2014

Res Chem Intermed

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In general, aryl-aryl transformations were investigated via transition metal-catalysed reactions. However, transition metal-mediated organic synthesis provided higher yields but has some flaws such as high cost, and the need for careful exclusion of air and moisture during the reactions. Possibly, there may be contamination of the product from traces of heavy metals present. To overcome these kinds of disadvantages, continuous efforts have been focused on the recent development of aryl-aryl formation through transition metal-free (TMF) reactions. However, most of these cross-couplings reaction were limited to hetero and electron-rich arenes which require strong inorganic bases. Our critical review includes a synthetic pathway to prepared X-aryl (X = C, N, O and S) motif by a transition metal-free scenario. Formerly, TMF reactions were carried out by various sources like strong bases, diazodium salt, aryliodonium salt, organo-catalysts and versatile energy sources like microwave heating, visible light and photochemical reactor. In this review, we have focused on the transition metal-free arylations.

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“…The employed organozinc reagents are relatively reactive nucleophiles undergoing rapid transmetalation with appropriate transition metal species, for instance palladium salts. This method has been successfully applied in the synthesis of bi(hetero)aryls [32–34] and thus also in those of C-substituted pyrazoles [35–36]. In our case, the reaction of iodopyrazoles 3a,b with different organozinc derivatives (Scheme 5) proceeded smoothly leading to the coupling products 6a,b and 9a,b – 11a,b in variable yields (19–87%).…”

Section: Resultsmentioning

confidence: 78%

Synthesis of tetrasubstituted pyrazoles containing pyridinyl substituents

Jansa¹,

Schmidt²,

Mamuye³

et al. 2017

Beilstein J. Org. Chem.

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A synthesis of tetrasubstituted pyrazoles containing two, three or four pyridinyl substituents is described. Hence, the reaction of 1,3-dipyridinyl-1,3-propanediones with 2-hydrazinopyridine or phenylhydrazine, respectively, affords the corresponding 1,3,5-trisubstituted pyrazoles. Iodination at the 4-position of the pyrazole nucleus by treatment with I2/HIO3 gives the appropriate 4-iodopyrazoles which served as starting materials for different cross-coupling reactions. Finally, Negishi cross-coupling employing organozinc halides and Pd catalysts turned out to be the method of choice to obtain the desired tetrasubstituted pyrazoles. The formation of different unexpected reaction products is described. Detailed NMR spectroscopic investigations (1H, 13C, 15N) were undertaken with all products prepared. Moreover, the structure of a condensation product was confirmed by crystal structure analysis.

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One-Pot Negishi Cross-Coupling Reactions of In Situ Generated Zinc Reagents with Aryl Chlorides, Bromides, and Triflates

Cited by 135 publications

References 15 publications

Catalyst Activation, Deactivation, and Degradation in Palladium‐Mediated Negishi Cross‐Coupling Reactions

Catalyst Activation, Deactivation, and Degradation in Palladium‐Mediated Negishi Cross‐Coupling Reactions

Synthetic journey towards transition metal-free arylations

Synthesis of tetrasubstituted pyrazoles containing pyridinyl substituents

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