Nickel-Catalyzed Monofluoroalkylation of Arylsilanes via Hiyama Cross-Coupling

Asymmetric Cobalt Catalysis for the Construction of Quaternary Stereogenic Centers with Fluorine Atoms

The advancement of robust synthetic methodologies for generating fluorinated quaternary carbon chiral centers is highly sought after in the fields of organic and medicinal chemistry. This study successfully provides such compounds through cobalt-catalyzed asymmetric Negishi coupling reactions of α-bromo-α-fluoro ketones with aryl/alkenyl zinc reagents. The adjustment of chiral unsymmetric N,N,N-tridentate (CUT) ligands played a key role in improving reactivity and selectivity in the cobalt catalysis, preventing the formation of hydrodebromination byproducts, and accommodating sterically hindered substrates and heterocycles. Control and kinetic experiments reveal that transmetalation serves as the rate-limiting step, a mechanistic characteristic that sets the newly developed asymmetric cobalt-catalyzed cross-couplings apart from previous methodologies.

Nickel-Catalyzed Stereospecific Alkylation of Vinylsiloxanes Using Pyridinium Salts

A methodology for radical cross-coupling with vinylsiloxanes and pyridinium salts under nickel catalysis is described. Easily implemented from inexpensive and abundant primary amines and terminal alkynes, this Hiyama coupling provides efficient access to (E), (Z), and (1,1')-alkenes with selectivity control. Operating under mild conditions, this robust strategy applies to a broad range of functional groups with diverse double bond stereochemistries. This versatile reaction is scalable and straightforward, accommodating both secondary and primary alkyl groups.

Trialkoxysilane-Induced Iridium-Catalyzed para-Selective C-H Bond Borylation of Arenes

An ideal approach for the construction of aryl boron compounds is to selectively replace a C-H bond in arenes with a C-B bond, and controlling regioselectivity is one of the most challenging aspects of these transformations. Herein, we report an iridium-catalyzed trialkoxysilane protecting group-assisted regioselective C-H borylation of arenes, including derivatives of benzaldehydes, acetophenones, benzoic acids, benzyl alcohols, phenols, aryl silanes, benzyl silanes, and multi-functionalized aromatic rings are all well tolerated and gave the para -selective C-H borylation products in a short time without the requirement of inert gases atmosphere. The site-selective C-H borylation can be adjustable by installing the developed trialkoxysilane protecting group on different functional groups on one aromatic ring. Importantly, the preparation process of the trialkoxychlorosilane is efficient and scalable. Mechanistic and computational studies reveal that the steric hindrance of the trialkoxysilane protecting group plays a key role in dictating the para-selectivity.

Visible-light-induced reactions of methylenecyclopropanes (MCPs)

Diverse, visible-light-induced transformations of methylenecyclopropanes (MCPs) have been reported in recent years, attracting significant attention from synthetic chemists. As readily accessible strained molecules, MCPs have sufficient reactivity to selectively generate different target products, through reactions with various radical species upon visible-light irradiation under regulated reaction conditions. These transformations can be classified into three subcategories of reaction pathway, forming ring-opened products, cyclopropane derivatives, and alkynes. These products include pharmaceutical intermediates and polycyclic/heterocyclic compounds that are challenging to obtain using traditional methods. This review summarizes the recent advancements in this field.

Transition Metal Catalyzed Hiyama Cross-Coupling: Recent Methodology Developments and Synthetic Applications

Hiyama cross-coupling is a versatile reaction in synthetic organic chemistry for the construction of carbon-carbon bonds. It involves the coupling of organosilicons with organic halides using transition metal catalysts in good yields and high enantioselectivities. In recent years, hectic progress has been made by researchers toward the synthesis of diversified natural products and pharmaceutical drugs using the Hiyama coupling reaction. This review emphasizes the recent synthetic developments and applications of Hiyama cross-coupling.

Copper-Promoted Hiyama Cross-Coupling of Arylsilanes With Thiuram Reagents: A Facile Synthesis of Aryl Dithiocarbamates

We report herein a facile Hiyama cross-coupling reaction of arylsilanes with thiuram reagents (tetraalkylthiuram disulfides or tetraalkylthiuram monosulfide) enabled by copper fluoride. Compared to our previous work, this protocol is an alternative protocol for the generation of S-aryl dithiocarbamates. It features low toxic and readily available substrates, cost-effective promoter, easy performance, and provides good yields.

Copper-Catalyzed Cross-Coupling of Arylacetylenes with Bromodifluoroacetamides

A copper-catalyzed radical difluoroalkylation of arylacetylenes with bromodifluoroamides has been developed. The reaction exhibits good functional group tolerance and allows acceA copper-catalyzed radical difluoroalkylation of arylacetylenes with bromodifluoroamides has been developed. The reaction exhibits good functional group tolerance and allows access to a variety of substituted α-alkynyl-α, α-difluoroacetamides in moderate to good yields. The potential for scale-up reaction and products derivatization also makes this method attractive for practical applications. Preliminary mechanistic studies suggest that a radical reaction pathway might be involved in the catalytic system.ss to a variety of substituted α-alkynyl-α, α-difluoroacetamides in moderate to good yields. The potential for scale-up reaction and products derivatization also makes this method attractive for practical applications. Preliminary mechanistic studies suggest that a radical reaction pathway might be involved in the catalytic system.

Silver-catalyzed monofluoroalkylation of heteroarenes with α-fluorocarboxylic acids: an insight into the solvent effect

A mild and efficient method for direct C-H monofluoroalkylation of heteroarenes with easily accessible and inexpensive α-fluorocarboxylic acids has been developed. This silver-catalyzed reaction affords mono- and bis-monofluoroalkylated heteroarenes in good yields under mild conditions, and the solvent effect on the monofluoroalkylation reaction is discussed in detail.

Transition-Metal-Catalyzed Monofluoroalkylation: Strategies for the Synthesis of Alkyl Fluorides by C-C Bond Formation

Alkyl fluorides modulate the conformation, lipophilicity, metabolic stability, and p K a of compounds containing aliphatic motifs and, therefore, have been valuable for medicinal chemistry. Despite significant research in organofluorine chemistry, the synthesis of alkyl fluorides, especially chiral alkyl fluorides, remains a challenge. Most commonly, alkyl fluorides are prepared by the formation of C-F bonds (fluorination), and numerous strategies for nucleophilic, electrophilic, and radical fluorination have been reported in recent years. Although strategies to access alkyl fluorides by C-C bond formation (monofluoroalkylation) are inherently convergent and complexity-generating, they have studied less than methods based on fluorination. This Review provides an overview of recent developments in the synthesis of chiral (enantioenriched or racemic) secondary and tertiary alkyl fluorides by monofluoroalkylation catalyzed by transition-metal complexes. We expect this contribution will illuminate the potential of monofluoroalkylations to simplify the synthesis of complex alkyl fluorides and suggest further research directions in this growing field.

Nickel-Catalyzed Cross-Coupling of Ethyl Chlorofluoroacetate with Aryl Bromides

A combinatorial nickel-catalyzed monofluoroalkylation of aryl bromides with the industrial raw regent ethyl chlorofluoroacetate has been developed. The two key factors to successful conversion are the combination of nickel with readily available nitrogen and phosphine ligands and the using of a mixture of different solvents. Mechanistic investigations indicated a new zinc regent might generated in situ and be involved in the reaction process.

Domino Heck/Hiyama cross-coupling: trapping of the σ-alkylpalladium intermediate with arylsilanes

A palladium-catalyzed domino Heck cyclization/Hiyama coupling reaction by the trapping of the σ-alkylpalladium intermediate with arylsilanes is described. A wide range of aryl-tethered alkenes and arylsilanes are all compatible with the reaction conditions. This approach shows good yields and excellent functional group tolerance, presenting a more practical and sustainable alternative to the conventional domino Heck cyclization/Suzuki coupling reaction.

Simple generation of various α-monofluoroalkyl radicals by organic photoredox catalysis: modular synthesis of β-monofluoroketones

A metal-free and operationally simple strategy for the generation of various α-monofluoroalkyl radicals has been developed. A combination of 1,4-bis(diarylamino)naphthalene photocatalyst and sulfoximine-based fluoroalkylating reagents is the key to success. The protocol can be applied to modular synthesis of β-monofluoroketones through radical monofluoroalkylation of alkenyl acetates.

Utilization of Unsymmetric Diaryliodonium Salts in α-Arylation of α-Fluoroacetoacetamides

The use of unsymmetric diaryliodonium salts as a versatile class of arylating agents has been demonstrated by developing a novel strategy to quickly access α-arylated α-fluoroacetoacetamides. The protocol provides a convenient metal-free method for the α-arylation of a diverse class of fluorinated acetoacetamides, and the products are obtained in good yields. The strategy, upon use of electron-deficient diaryliodonium salts as an arylating agent, provides α-fluoroacetamides through a spontaneous arylation/deacylation cascade.

Copper-Catalyzed Bromodifluoroacetylative Cyclization of Enynes

A copper-catalyzed bromodifluoroacetylative cyclization reaction is described. The treatment of bromodifluoroacete derivatives by CuI and B₂Pin₂ enables difluoroalkyl radical generation and triggers the radical addition/cyclization/bromination sequences. Bromodifluoroacetyl-derived ester, amide, and ketone were compatible and gave various vinyl C-Br bonds containing functionalized heterocycles in good yields.

Ligand-free copper-catalyzed regio- and stereoselective 1,1-alkylmonofluoroalkylation of terminal alkynes

A novel copper-catalyzed highly regio- and stereoselective 1,1-alkylmonofluoroalkylation of terminal alkynes without an external ligand has been developed.

Metal-free α-arylation of α-fluoro-α-nitroacetamides employing diaryliodonium salts

Herein, we present a mild and efficient metal-free arylation of α-fluoro-α-nitroacetamides employing diaryliodonium salts. A broad range of diaryliodonium salts and α-fluoro-α-nitroacetamides containing sensitive functional groups was successfully employed in this protocol to yield the arylated products in good yields. The synthetic value of this novel protocol was further highlighted by extending the α-arylation to α-cyano-α-fluoroacetamides.

Palladium-Catalyzed Hiyama Cross-Couplings of Arylsilanes with 3-Iodoazetidine: Synthesis of 3-Arylazetidines

The first palladium-catalyzed Hiyama cross-coupling reactions of arylsilanes with 3-iodoazetidine were described. The protocol provides a convenient access to a variety of useful 3-arylazetidines which are of great interest in pharmaceutical laboratories in moderate to good yields (30%-88%). In addition, this strategy has the advantage of easy operation and mild reaction conditions.

Nickel-Catalyzed Coupling Reaction of α-Bromo-α-fluoroketones with Arylboronic Acids toward the Synthesis of α-Fluoroketones

A nickel-catalyzed coupling reaction of α-bromo-α-fluoroketones with arylboronic acids was reported, which provides an efficient pathway to access 2-fluoro-1,2-diarylethanones in high yields. We also disclosed the synthesis of the monofluorination agents α-bromo-α-fluoroketones by using a trifluoroacetate release protocol. Mechanistic investigation indicated that a monofluoroalkyl radical is involved in the catalytic circle. Moreover, an important medical intermediate of flindokalner was synthesized via a nickel-catalyzed coupling reaction of α-bromo-α-fluoro-2-indolone and boronic ester.

Synthesis of 18F-difluoromethylarenes using aryl boronic acids, ethyl bromofluoroacetate and [18F]fluoride

Herein, we report the radiosynthesis of 18F-difluoromethylarenes via the assembly of three components, a boron reagent, ethyl bromofluoroacetate, and cyclotron-produced non-carrier added [18F]fluoride. The two key steps are a copper-catalysed cross-coupling reaction, and a Mn-mediated 18F-fluorodecarboxylation.

Irradiation-Induced Cobaloxime-Catalyzed C-H Monofluoroalkylation of Styrenes at Room Temperature

A cobaloxime-catalyzed photochemical synthesis of allyl monofluorides from styrenes is described herein. This method is characterized by mild reaction conditions, low-cost catalyst, and broad substrate scope. Furthermore, this convenient method will provide a facile synthesis toward novel monofluoroalkylated natural product and pharmaceutical derivatives. Mechanistic investigations indicate that a monofluoroalkyl radical is involved in the catalytic cycle.

Nickel-catalyzed fluoroethylation of arylboronic acids via Suzuki-type coupling

A new and step-economic method for the synthesis of homobenzylic fluorides through nickel-catalyzed Suzuki-type fluoroethylation coupling is developed.

Nickel-catalyzed monofluoromethylation of (hetero)aryl bromides via reductive cross-coupling

Nickel-catalyzed direct monofluoromethylation of (hetero)aryl bromides with industrial raw material BrCH₂F by reductive cross-coupling has been developed.

Nickel-Catalyzed Reductive Cross-Coupling of Aryl Halides with Monofluoroalkyl Halides for Late-Stage Monofluoroalkylation

A combinatorial nickel-catalyzed monofluoroalkylation of aryl halides with unactivated fluoroalkyl halides by reductive cross-coupling has been developed. This method demonstrated high efficiency, mild conditions, and excellent functional-group tolerance, thus enabling the late-stage monofluoroalkylation of diverse drugs. The key to success was the combination of diverse readily available bidentate and monodentate pyridine-type nitrogen ligands with nickel, which in situ generated a variety of readily tunable catalysts to promote fluoroalkylation with broad scope with respect to both coupling partners. This combinatorial catalysis strategy offers a solution for nickel-catalyzed reductive cross-coupling reactions and provides an efficient way to synthesize fluoroalkylated druglike molecules for drug discovery.