Transformations of Less-Activated Phenols and Phenol Derivatives via C–O Cleavage

Chemical Reviews, Journal Year: 2020, Volume and Issue: 120(18), P. 10454 - 10515

Published: Aug. 28, 2020

Employing phenols and phenol derivatives as electrophiles for cross-coupling reactions has numerous advantages over commonly used aryl halides in terms of environmental-friendliness sustainability. In the early stage discovering such transformations, most efforts have been devoted to utilizing highly activated sulfonate types (e.g., OTf, OTs, etc.), which similar reactivities corresponding halides. However, a continuing scientific challenge is how achieve direct C-O functionalizations relatively less-activated more efficiently. this review, we will focus on recent updates derivatives, from carboxylates pivalates, acetates, carbamates carbonates, ethers (anisoles, diaryl ethers, pyridyl silyl ethers), phenolate salts, ultimately simply unprotected phenols, sorted by bond formations. Both transition-metal-catalyzed transition-metal-free protocols be covered discussed detail. Instead, sulfonates not extensively unless they are closely related, due their high reactivity. Since represent main linkages or units lignin biomass, successes transformations potentially make major contributions biomass upgrading depolymerization.

Language: Английский

---

Selective Decarbonylation via Transition-Metal-Catalyzed Carbon–Carbon Bond Cleavage

Chemical Reviews, Journal Year: 2020, Volume and Issue: 121(1), P. 365 - 411

Published: June 16, 2020

Transition-metal-catalyzed decarbonylation via carbon–carbon bond cleavage is an essential synthetic methodology. Given the ubiquity of carbonyl compounds, selective decarbonylative process offers a distinct strategy using groups as "traceless handles". This reaction has been significantly developed in recent years many respects, including catalytic system development, mechanistic understanding, substrate scope, and application synthesis complex functional molecules. Therefore, this review aims to summarize progress on transition-metal-catalyzed process, from discovery new transformations understanding mechanisms, reveal great achievements potentials field. The contents are categorized by type chemical process. main challenges opportunities also examined with goal expanding range reactions.

Language: Английский

---

Decarbonylative Cross-Couplings: Nickel Catalyzed Functional Group Interconversion Strategies for the Construction of Complex Organic Molecules

Accounts of Chemical Research, Journal Year: 2018, Volume and Issue: 51(5), P. 1185 - 1195

Published: April 13, 2018

ConspectusThe utilization of carboxylic acid esters as electrophiles in metal-catalyzed cross-coupling reactions is increasingly popular, environmentally friendly and readily available ester derivatives can be powerful alternatives to the commonly used organohalides. However, key challenges associated with use these chemicals remain addressed, including stability substrates high energy barrier their oxidative addition low-valent metal species. Due recent developments nickel catalysis that make it easier perform additions, chemists have become interested applying less reactive coupling counterparts nickel-catalyzed transformations. Hence, our group others independently investigated various substitutions functionalizations enabled by catalysis. Such methods are great interest they enable exchange groups, which directing groups C–H prior replacement.Here, we summarize efforts toward development decarbonylative esters. Achievements accomplished other this area also included. To day, a number new transformations been successfully developed, arylations, alkylations, cyanations, silylations, borylations, aminations, thioetherifications, stannylations, hydrogenolysis reactions. These proceed via pathway shown degree reactivity chemoselectivity, well several unique advantages terms substrate availability, due partners.Although mechanisms not yet fully understood, already provided some important insights. For example, Yamamoto explored stoichiometric nickel-mediated decarbonylation process proposed reaction mechanism involving C(acyl)–O bond cleavage CO extrusion. Key intermediates were isolated characterized Shi co-workers, supporting assumption nickel/N-heterocyclic carbene-promoted activation functionalization. Our combined experimental computational study ligand-controlled chemoselective aromatic alkylboron reagents further insight into mechanism.We demonstrated complexes bidentate ligands favor C(aryl)–C step, resulting while monodentate phosphorus promote bond, leading production ketone products. Although more detailed mechanistic investigations need undertaken, successful serve solid foundation for future studies.We believe type will significant value, particularly combination retrosynthetic analysis synthesis natural products biologically active molecules. Thus, presented substitution pave way applications construction complex frameworks late-stage modification functionalization derivatives.

Language: Английский

---

Trends in the Usage of Bidentate Phosphines as Ligands in Nickel Catalysis

Chemical Reviews, Journal Year: 2020, Volume and Issue: 120(13), P. 6124 - 6196

Published: June 3, 2020

A critically important process in catalysis is the formation of an active catalyst from combination a metal precursor and ligand, as efficacy this reaction governs amount catalyst. This Review comprehensive overview reactions catalyzed by nickel added bidentate phosphine, focusing on steps transforming precatalyst ligand into potential effects transformation catalysis. Reactions covered include common cross-coupling reactions, such Suzuki, Heck, Kumada, Negishi couplings, addition cycloadditions, C–H functionalizations, polymerizations, hydrogenations, reductive among others. Overall, most widely used with free phosphines Ni(cod)2, which accounts for ∼50% reports surveyed, distantly followed Ni(acac)2 Ni(OAc)2, account ∼10% each. By compiling these we have calculated statistics usage each Ni(cod)2 other sources. The are simple, relatively inexpensive ligands, DPPE, DCPE, DPPP, DPPB, along others more complex backbones, DPPF Xantphos. use expensive chiral scattered, but ligands BINAP, Me-Duphos, Josiphos, related analogs.

Language: Английский

---

Ligand-Controlled Chemoselective C(acyl)–O Bond vs C(aryl)–C Bond Activation of Aromatic Esters in Nickel Catalyzed C(sp²)–C(sp³) Cross-Couplings

Journal of the American Chemical Society, Journal Year: 2018, Volume and Issue: 140(10), P. 3724 - 3735

Published: Feb. 20, 2018

A ligand-controlled and site-selective nickel catalyzed Suzuki–Miyaura cross-coupling reaction with aromatic esters alkyl organoboron reagents as coupling partners was developed. This methodology provides a facile route for C(sp2)–C(sp3) bond formation in straightforward fashion by successful suppression of the undesired β-hydride elimination process. By simply switching phosphorus ligand, ester substrates are converted into alkylated arenes ketone products, respectively. The utility this newly developed protocol demonstrated its wide substrate scope, broad functional group tolerance application synthesis key intermediates bioactive compounds. DFT studies on oxidative addition step helped rationalizing intriguing chemoselectivity: whereas complexes bidentate ligands favor C(aryl)–C cleavage leading to product via decarbonylative process, monodentate activation C(acyl)–O bond, which later generates product.

Language: Английский

---

Transition‐Metal‐Catalyzed Decarbonylative Coupling Reactions: Concepts, Classifications, and Applications

Chemistry - A European Journal, Journal Year: 2018, Volume and Issue: 24(31), P. 7794 - 7809

Published: May 14, 2018

Abstract Transition metal‐catalyzed decarbonylative coupling reactions have emerged as a powerful alternative to conventional cross‐coupling protocols due the advantages associated with use of carbonyl‐containing functionalities electrophiles instead commonly used organohalides or sulfates. A wide variety novel transformations based on this concept been successfully achieved, including carbon–carbon and carbon–heteroatom bond forming reactions. In Review, we summarize recent progress in field present comprehensive overview carbonyl derivatives.

Language: Английский

---

Nickel(II)-Catalyzed Site-Selective C–H Bond Trifluoromethylation of Arylamine in Water through a Coordinating Activation Strategy

Organic Letters, Journal Year: 2017, Volume and Issue: 19(20), P. 5661 - 5664

Published: Oct. 2, 2017

The first example of nickel(II)-catalyzed site-selective C-H bond trifluoromethylation arylamine in water is established. In this transformation, a coordinating activation strategy performed by the utilization picolinamide as directing group, and target products are obtained moderate to good yields. addition, catalyst-in-water system can be reutilized eight times with slight loss catalytic activity applied green, concise synthesis acid red 266. Furthermore, series control experiments verify that single-electron transfer mechanism responsible for reaction.

Language: Английский

---

Rapidly Activating Pd-Precatalyst for Suzuki–Miyaura and Buchwald–Hartwig Couplings of Aryl Esters

The Journal of Organic Chemistry, Journal Year: 2017, Volume and Issue: 83(1), P. 469 - 477

Published: Dec. 1, 2017

Esters are valuable electrophiles for cross-coupling due to their ubiquity and ease of synthesis. However, harsh conditions traditionally required the effective ester substrates. Utilizing a recently discovered precatalyst, Pd-catalyzed Suzuki-Miyaura Buchwald-Hartwig reactions involving cleavage C(acyl)-O bond aryl esters that proceed under mild reported. The Pd(II) precatalyst is highly active because it reduced Pd(0) species more rapidly than previous precatalysts.

Language: Английский

---

Palladium‐Catalyzed Decarbonylative Difluoromethylation of Acid Chlorides at Room Temperature

Angewandte Chemie International Edition, Journal Year: 2018, Volume and Issue: 57(51), P. 16871 - 16876

Published: Oct. 24, 2018

Abstract Methods for the direct synthesis of difluoromethylated arenes are sparse, despite importance difluoromethyl group in medical, agro‐, and materials chemistry. A palladium‐catalyzed decarbonylative cross‐coupling reaction acid chlorides with a zinc reagent is achieved to access compounds. The transformation proceeds at room temperature shows broad functional tolerance, thus providing general efficient method difluoromethylation wide range aromatic carboxylic acids.

Language: Английский

---

Decarbonylative C–P Bond Formation Using Aromatic Esters and Organophosphorus Compounds

Organic Letters, Journal Year: 2018, Volume and Issue: 20(4), P. 1150 - 1153

Published: Feb. 2, 2018

Ni-catalyzed C–P bond formation was achieved using aromatic esters as unconventional aryl sources. The key to success the use of a thiophene-based diphosphine ligand (dcypt). Several including heteroaromatics can be coupled with phosphine oxides and phosphates, providing phosphorus compounds. synthetic utility method demonstrated by application present protocol sequential coupling reactions.

Language: Английский

---