PdII‐Catalyzed Monoselective ortho Halogenation of CH Bonds Assisted by Counter Cations: A Complementary Method to Directed ortho Lithiation

Mei, Tian Sheng; Giri, Ramesh; Maugel, Nathan; Yu, Jin

doi:10.1002/anie.200705613

Cited by 335 publications

(124 citation statements)

References 67 publications

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“…Following ligand-promoted C–H olefination, Pd/C-mediated hydrogenation, and tert -butyl ester deprotection, free acid 239 was obtained in 66% yield over the three steps. Next, we found that 239 could undergo directed ortho -C–H iodination 82 to give differentially functionalized 1,2,4,5-tetrasubstituted arene 240 in 67% yield following conversion to the methyl ester to simplify purification.…”

Section: Identification Of Ligand Scaffolds For Pd(ii)-catalyzed Cmentioning

confidence: 99%

Developing Ligands for Palladium(II)-Catalyzed C–H Functionalization: Intimate Dialogue between Ligand and Substrate

2013

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Homogeneous transition metal–catalyzed reactions are indispensable to all facets of modern chemical synthesis. It is thus difficult to imagine that for much of the early 20th century, the reactivity and selectivity of all known homogeneous metal catalysts paled in comparison to their heterogeneous and biological counterparts. In the intervening decades, advances in ligand design bridged this divide, such that today some of the most demanding bond-forming events are mediated by ligand-supported homogeneous metal species. While ligand design has propelled many areas of homogeneous catalysis, in the field of Pd(II)-catalyzed C–H functionalization, suitable ligand scaffolds are lacking, which has hampered the development of broadly practical transformations based on C–H functionalization logic. In this review, we offer an account of our research employing three ligand scaffolds, mono-N-protected amino acids, 2,6-disubstituted pyridines, and 2,2′-bipyridines, to address challenges posed by several synthetically versatile substrate classes. Drawing on this work, we discuss principles of ligand design, such as the need to match a ligand to a particular substrate class, and how ligand traits such as tunability and modularity can be advantageous in reaction discovery.

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Section: Identification Of Ligand Scaffolds For Pd(ii)-catalyzed Cmentioning

confidence: 99%

Developing Ligands for Palladium(II)-Catalyzed C–H Functionalization: Intimate Dialogue between Ligand and Substrate

2013

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“…[1,[4][5][6][7][8] With respect to Pd catalysis, Yu and co-workers have pioneered the use of carboxylate groups as effective promoters of Pd-catalyzed selective CÀH functionalization, [5] which has led to seminal developments in cross-coupling with arylorganometallic reagents; [5a,b, 6] further developments have led to carbonylation, [5c] alkylation, [5d] olefination, [5e,f] oxygenation, [5g] and iodination [5h,i] reactions. Related to this, other carbonyl-based directing groups such as amide derivatives, [7] ketones, [8] and oximes [9] have also resulted in developments in catalytic CÀH bond functionalization.…”

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confidence: 99%

Palladium(II)‐Catalyzed CH Bond Arylation of Electron‐Deficient Arenes at Room Temperature

et al. 2010

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“…Other solvents, such as DMF, DMSO, dioxane, THF, EtOH and EtOAc were ineffective(Entries 12-16 and 19, Table 1). Our previous studies have shown that acyl hypobromite(BrOAc) generated in situ from carboxylic acid and NBS was more active than NBS(Scheme 2) [32,36] . Accordingly, the effect of carboxylic acids on the bromination was investigated in this paper and the result is consistent with that of the early report [32] .…”

Section: Scheme 1 Synthesis Of Compound 1bmentioning

confidence: 99%

Cu-catalyzed aryl C-H halogenation using N-halosuccinimides via assistance of benzoic acid

Gao

Lin

2015

Chem. Res. Chin. Univ.

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Aryl halides are a kind of extremely valuable compounds used in transition-metal-catalyzed coupling reactions, as well as important structure motifs in many natural products and manufactured drugs [1,2] . The classical approach for preparation of haloarenes is electrophilic aromatic substitution(EAS) using various halogenating reagents or oxidative halogenations with halogenating reagent generated in situ from halides and oxidants, such as peroxide, oxygen and meta-cholorperoxybenzoic acid(mCPBA) [3,4] . However, harsh reaction conditions are required for halogenation of less active aromatics. orthoMetalation followed by halogen quenching is another approach for halogenation of aromatics [5] . However, there are obvious drawbacks for these methods，such as low regioselectivity, harsh conditions and even dangerous procedures. Therefore, the development of an alternative and practical way remains challenge in organic synthesis.As a complementary method for halogenation of deactivated aromatics, in 2004, a means to halogenate aromatics, including deactivated ones was developed by Olah and co-workers [6] , with N-halosuccinimides(NXS)/BF 3 -H 2 O system. And in 2010, Wang and co-workers [7] achieved an efficient Au-catalyzed halogenation of aromatics with electron-donating group(EDG) or electron-withdrawing group(EWG) using NXS. In addition, transtion-metal-catalyzed C-H bond functionalization of aromatic compounds has attracted considerable attention and has gradually become a benign and environmentally friendly tool in organic synthesis [8][9][10][11][12][13][14] . The functionalizations including arylation, alkoxylation, acylation, olefination, amidation, nitration and halogenation have been achieved [15] . So far, the halogenation of aromatics catalyzed by Pd [15][16][17][18][19][20][21] , Rh [22,23] , Au [7] and Cu [24][25][26][27][28][29][30][31][32] has been developed. In the past decade, C-H activation/C-X(X=halogen) coupling catalyzed by precious metal has made great progress. In particular, there have been many reports about Pd-catalyzed halogenation. However, residue of poisonous and harmful heavy metal and high cost have restricted its practical application. C-H functionalization catalyzed by ordinary transition metal is the direction of future development, and has profound significance on the development of organic chemistry theory and application in the chemical industry. Halogenation reactions with inexpensive Cu as metal catalyst have been developed recently. We have previously exploited a highly efficient and practical protocol for the selective preparation of mono-and di-halogenated 2-arylpyridine via conjunctive use of carboxylic acids and solvents [32] . Using stoichiometric amount of CuX(X=Br or Cl) is a disadvantage for the method. In our ongoing investigation of the reaction, we have drawn our attention to counter ions of Cu-catalysts owing to the halide effects of transition metal catalysis. Halide ions of transition-metal complex are not only counter ions, but also ligands with important prope...

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Pd^II‐Catalyzed Monoselective ortho Halogenation of CH Bonds Assisted by Counter Cations: A Complementary Method to Directed ortho Lithiation

Cited by 335 publications

References 67 publications

Developing Ligands for Palladium(II)-Catalyzed C–H Functionalization: Intimate Dialogue between Ligand and Substrate

Developing Ligands for Palladium(II)-Catalyzed C–H Functionalization: Intimate Dialogue between Ligand and Substrate

Palladium(II)‐Catalyzed CH Bond Arylation of Electron‐Deficient Arenes at Room Temperature

Cu-catalyzed aryl C-H halogenation using N-halosuccinimides via assistance of benzoic acid

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