Ligand‐Promoted Non‐Directed C−H Cyanation of Arenes

Liu, Luo‐Yan; Yeung, Kap‐Sun; Yu, Jin‐Quan

doi:10.1002/chem.201805772

Cited by 81 publications

(88 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The resulting mixture was purified by silica gel chromatography (EtOAc/hexane = 1/20) to afford 1i as a colorless liquid (588 mg, 97% yield). 1 After the reaction completed, the reaction mixture was filtered through a pad of Celite and the solvent was evaporated to give the crude product. The crude product was purified by column chromatography on silica gel (EtOAc/hexane = 1/5) to afford 1m as a gray-white solid (636 mg, 78% yield).…”

Section: Experimental Section 21 Preparation Of Substratesmentioning

confidence: 99%

“…Gray solid, 94% yield. 1 General procedure for synthesis of ortho and meta regiomers: To a 10 mL Schlenck tube was charged with phenoxathiin-10-oxide 2n (55.7 mg, 0.24 mmol, 1.2 equiv. ), CH2Cl2 (0.5 mL) and ArB(OH)2 (0.2 mmol, 1.0 equiv.…”

Section: S12mentioning

confidence: 99%

“…in the next step to provide the product 4q (23.1 mg, 52% isolated yield) after purification by preparative thin-layer chromatography (n-hexane/ethyl acetate = 80/1). 1 Following the general procedure provided the product 4u (38.4 mg, 69% isolated yield) after purification by preparative thin-layer chromatography (n-hexane/ethyl acetate = 10/1), 15% NMR yield of starting materials were not recoverd. 1 Following the general procedure provided the product 4y (80% NMR yield), (38.5 mg, 43% isolated yield) after S34 purification by preparative thin-layer chromatography (n-hexane/ethyl acetate = 10/1).…”

Section: Efficiency and Regioselectivity For Sulfonium Salt Formationmentioning

confidence: 99%

“…Tremendous efforts have been made in the field of precise control the site selectivity in C-H functionalization of aromatics during the past two decades. [1][2] However, achieving para-selectivity in direct C-H functionalization reactions remains a significant challenge, especially when the targeted arene owns multiple reactive sites with subtle steric and electronic discrepancy. Typically, para-selectivity control often dominated by steric and electronic factors of substrates, and high selectivity was observed mainly for electron-rich arenes, which have been represented in electrophilic aromatic substitution reaction of aromatics.…”

mentioning

confidence: 99%

See 3 more Smart Citations

Para-selective borylation of monosubstituted benzenes using a transient mediator

et al. 2019

View full text Add to dashboard Cite

Herein, we conceptualized a transient mediator approach that has the capability of para-selective C-H functionalization of monosubstituted aromatics. This approach is enabled by in situ generation of a versatile sulfonium salt via highly electrophilic phenoxathiine or thianthrene dication intermediate which can be readily generated from its sulfoxide with trifluoromethanesulfonic anhydride. Preliminary mechanistic study implied that the remarkable para selectivity might be related to the incredible electrophilicity of thianthrene dication intermediate. The versatility of this approach was demonstrated via para-borylation of various monosubstituted simple aromatics combining the sulfonium salt formation with further photocatalyzed transformation. 4 Scheme 4. Transformation of Aryl Boron Conditions: a) CH=CHCO2Et, Pd(OAc)2 (10 mol %), Na2CO3 (2.0 equiv), DMF, 50 o C, O2, 3 h; b) PhBr (1.0 equiv), Pd(dppf)Cl2 (5 mol %), K3PO4 (3.0 equiv), H2O (5.0 equiv), THF, 70 o C, 3 h; c) KI (1.5 equiv), CuI (10 mol %), 1,10-phenanthroline (20 mol %), MeOH/H2O (4:1), 80 o C, 20 h; d) MeOH, Cu(OAc)2 (1.0 equiv), DMAP (2.0 equiv), 4 Å MS, rt, air, 24 h; e) morpholine (2.0 equiv), Cu(OAc)2 (1.0 equiv), Et3N (2.0 equiv), 4 Å MS, CH3CN, 80 o C, air, 24 h. In summary, para-borylation of monosubstituted benzenes has been demonstrated using phenoxathiine or thianthrene as the transient mediator. Preliminary mechanistic study indicated that the key to the remarkable para-selectivity might be the use of highly electrophilic phenoxathiine or thianthrene dication species. Detailed mechanistic study and the application of this transient mediator approach for site-selective functionalization are ongoing projects in our laboratory. Experimental procedures, complete characterization data, copies of

show abstract

Section: Experimental Section 21 Preparation Of Substratesmentioning

confidence: 99%

Section: S12mentioning

confidence: 99%

Section: Efficiency and Regioselectivity For Sulfonium Salt Formationmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Para-selective borylation of monosubstituted benzenes using a transient mediator

et al. 2019

View full text Add to dashboard Cite

show abstract

“…[8] Subsequent studies by the groups of Ritter, Yu, and ourselves demonstrated the generality of these catalyst systems through the development of arene-limited nondirected C-H cyanation reactions suitable for late-stage benzonitrile synthesis. [9,10] Recently our group has developed an arene-limited nondirected C-H alkynylation. [11] Furthermore, we could recently demonstrate that this design can also be applied to devise sterically controlled heteroarene functionalizations.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of the Arene-Limited Nondirected C–H Activation of Arenes with Palladium

Wedi¹,

Farizyan²,

Bergander³

et al. 2020

Preprint

View full text Add to dashboard Cite

Palladium catalysts have recently been discovered that enable the directing group-free C–H activation and functionalization of arenes without requiring an excess of the arene substrate. By overcoming this long standing challenge, the resulting synthetic methods have now become suitable for the functionalization of complex organic molecules. The key to success in several of these transformations has been the use of two complementary ligands, an N-acyl amino acid and an N-heterocycle. Further applications of this design principle will likely require the guidance by a profound mechanistic understanding. This prompted us to engage in a detailed experimental and computational mechanistic study of the dual ligandenabled C–H activation of arenes. Based on comprehensive kinetic experiments, (CID-)MS and DOSY-NMR measurements, and DFT calculations we find that a 1:1:1 complex of palladium and the two ligands is the active species that enables a partially rate-limiting concerted C–H activation as part of a PdII/Pd0-cycle. Our study highlights the importance of catalyst speciation and allows us to rationalize the role of each ligand as well as the observed regioselectivities. These findings are expected to be highly useful for further method development using this powerful class of catalysts.

show abstract

Addition Reactions: Polar Addition

Kočovský¹

2023

Organic Reaction Mechanisms Series

View full text Add to dashboard Cite

Ligand‐Promoted Non‐Directed C−H Cyanation of Arenes

Cited by 81 publications

References 32 publications

Para-selective borylation of monosubstituted benzenes using a transient mediator

Para-selective borylation of monosubstituted benzenes using a transient mediator

Mechanism of the Arene-Limited Nondirected C–H Activation of Arenes with Palladium

Addition Reactions: Polar Addition

Contact Info

Product

Resources

About