Iron‐Catalyzed C?N Cross‐Coupling of Sulfoximines with Aryl Iodides

An inexpensive and experimentally simple, iron‐catalyzed N‐arylation reaction of NH‐sulfoximines with aryl iodides is reported. This complementary method to the known palladium‐ and copper‐catalyzed ones features the use of a combination of environmentally friendly FeCl₃ and N,N′‐dimethylethylenediamine (DMEDA) as catalytic system and allows the efficient preparation of various N‐arylsulfoximines in high yields.     

Palladium‐Catalyzed C?N Cross‐Coupling of N′‐Monosubstituted Sulfondiimines with Aryl Bromides

A general method for the N‐arylation of sulfondiimines with aryl bromides using tris(dibenzylideneacetone)dipalladium(0) [Pd₂(dba)₃] and 2‐dicyclohexylphosphino‐2′,6′‐diisopropoxybiphenyl (RuPhos) as catalyst system was developed. A new benzothiazine was obtained, and a protocol for the cleavage of para‐methoxyphenyl (PMP) groups in PMP‐protected sulfondiimines has been found, which provides access to synthetically useful NH‐derivatives, that are difficult to prepare by other means.     

Copper‐Catalyzed Intermolecular Amination of Acidic Aryl C?H Bonds with Primary Aromatic Amines

A copper‐catalyzed intermolecular aerobic oxidative C H bond amination of various polyfluorobenzenes with an array of primary aromatic amines was achieved for the first time. The reactivity of the polyfluorobenzenes was observed to depend on the acidity of C H bonds. Under similar reaction conditions, the C H bond amination of azoles also occurred.     

Copper‐Catalyzed Cross‐Dehydrogenative Coupling (CDC) of Alkynes and Benzylic C?H Bonds

The activation of benzylic C H bonds and subsequent coupling with terminal alkynes in the presence of 2,3‐dichloro‐5,6‐dicyanoquinone (DDQ) and a catalytic amount of copper(I) triflate is presented. Good to moderate yields of disubstituted alkynes are obtained for this cross‐dehydrogenative coupling (CDC) reaction between a variety of aromatic alkynes and diphenylmethane derivatives.     

A New,Efficient and Recyclable Lanthanum(III) Oxide‐ Catalyzed C?N Cross‐Coupling

A new and efficient protocol for the C N cross‐coupling of aryl halides with heteroaromatic amines in the presence of lanthanum(III) oxide (10 mol%) as a recyclable catalyst, N,N′‐dimethylethylenediamine (DMEDA) (20 mol%) and potassium hydroxide (KOH) as a base in dimethyl sulfoxide (DMSO) at 110 °C has been developed. This inexpensive catalytic system is highly effective towards the amination of aryl halides with various nitrogen nucleophiles and is significantly tolerant towards other functional groups in the substrates.     

Synthesis of Isoquinolines via Rhodium(III)‐Catalyzed Dehydrative C?C and C?N Coupling between Oximines and Alkynes

Isoquinolines have been synthesized from the redox‐neutral dehydrative C N and C C cross‐coupling between oximines and alkynes using a catalytic amount of (pentamethylcyclopentadiene)rhodium dichloride dimer {[RhCp*Cl₂]₂} and cesium acetate (CsOAc), a process that involves ortho C H activation of oximines and subsequent functionalization with alkynes. This redox‐neutral catalytic isoquinoline synthesis operates under mild conditions, and is insensitive to moisture or air. A broad scope of coupling partners has been established, and a likely mechanism has been suggested.     

Rhodium‐Catalyzed C?H Olefination of Aryl Weinreb Amides

A rhodium(III)‐catalyzed oxidative C H olefination directed by Weinreb amides, a class of well developed versatile building blocks in organic synthesis, has been developed with air as the terminal oxidant. The reactions proceed with excellent reactivity, good functional group tolerance and high yields.     

Palladium(II)‐Catalyzed Direct ortho‐C?H Acylation of Anilides by Oxidative Cross‐Coupling with Aldehydes using tert‐Butyl Hydroperoxide as Oxidant

An efficient palladium‐catalyzed C H acylation with aldehydes using tert‐butyl hydroperoxide (TBHP) transforms various anilides into synthetically useful 2‐aminobenzophenone derivatives under mild conditions (40 °C, 3 h). The acylation reaction exhibits excellent regioselectivity and functional group tolerance, and simple aromatic aldehydes, functionalized aliphatic aldehydes and heteroaromatic aldehydes are effective coupling partners. The acylation reaction is probably initiated by a rate‐limiting electrophilic C H cyclopalladation (k_H/k_D=3.6; ρ⁺=−0.74) to form an arylpalladium complex, followed by acyl radical functionalization.     

Tetrabutylammonium Iodide‐Catalyzed Phosphorylation of Benzyl C?H Bonds via a Cross‐Dehydrogenative Coupling (CDC) Reaction

Phosphate esters play important roles as biological active principles and synthons in chemistry. An efficient metal‐free approach for the synthesis of phosphate esters through sp³ C H activation is described. By using tetrabutylammonium iodide (Bu₄NI) as a catalyst and tert‐butyl hydroperoxide (TBHP) as an oxidant, various toluene derivatives and phosphorus nucleophiles are tolerated in this transformation, affording the corresponding products in moderate to good yields.

     

Stable Nickel(0) Phosphites as Catalysts for C?N Cross‐Coupling Reactions

Herein we describe the design and preparation of inexpensive, air‐stable nickel phosphite‐based catalysts for use in the C N cross‐coupling reaction. The combination of nickel tetrakis(triphenyl phosphite) {Ni[P(OPh)₃]₄} and 1,1′‐bis(diphenylphosphino)ferrocene (dppf), and in particular a newly developed catalyst (dppf)Ni[P(OPh)₃]₂, were found to be extremely effective in catalyzing a range of amination reactions of anilines and amines with aryl chlorides. This new catalyst system offers an alternative to the bis(cyclooctadienyl)nickel [Ni(COD)₂] and palladium(0) catalysts commonly used for C N bond formation.

     

Lewis Acid‐Catalyzed Generation of C?C and C?N Bonds on π‐Deficient Heterocyclic Substrates

Focused microwave irradiation of a series of halogenated nitrogen heterocycles and different kinds of nucleophiles in the presence of a catalytic amount of indium trichloride leads to the efficient and completely regioselective generation of aromatic C C and C N bonds. The method is simple, rapid, general and inexpensive, and can be performed without the use of dried solvents. Most of the synthetized compounds are new and in many cases the work‐up required only filtration. Furthermore, this is the first example of the use of a Lewis acid as a catalyst for heteroarylation, vinylation and amination reactions on π‐deficient heterocyclic substrates.

     

Iridium Complex‐Catalyzed Cross‐Coupling Reaction of Terminal Alkynes with Internal Alkynes via C?H Activation of Terminal Alkynes

The cross‐dimerization of an electron‐rich terminal alkyne with an electron‐deficient internal alkyne was promoted by an iridium complex to produce a 1 : 1 adduct in high regio‐ and stereoselectivities. This reaction was extended to various combinations of terminal alkynes with internal alkynes such as alkynyl esters and alkynyl aldehydes. The selectivity of the reaction was found to markedly depend on the ligands used. When dppe was used as a ligand, the 1 : 2 cross‐cyclotrimerization reaction took place to form substituted benzene derivatives. A plausible reaction path was suggested based on a labeling experiment. This reaction provides a method for the production of complicated enynes which are difficult to be prepared by conventional methods.     

Iron‐Catalyzed C?C Bond Cleavage and C?N Bond Formation

A novel approach for C N bond formation was developed by iron‐catalyzed C C bond cleavage. Anilines and sulfonamides reacted smoothly with 2‐substituted 1,3‐diphenylpropane‐1,3‐diones to afford N‐alkylation products, in which the 1,3‐dicarbonyl group acts as a leaving group in the presence of an iron catalyst. The reversible C C bond cleavage plays a driving force to give the thermodynamically stable products. The method is complementary to the previous methods for C N bond formation.     

Chemo‐Controlled Cross‐Coupling of Di(hetero)aryl Disulfides with Grignard Reagents: C?C vs. C?S Bond Formation

A general protocol for the chemoselectivity‐controlled C C and C S coupling reactions of di(hetero)aryl disulfides with Grignard reagents catalyzed by ferrocene and palladium acetate has been developed. Ferrocene favored the formation of C S coupled products at low temperature, whereas C C bond couplings were favored when palladium acetate was used. All the reactions proceeded with excellent chemoselectivity and in good yields under mild conditions, and a library of molecules with pyridine and pyrimidine scaffolds was produced.

     

Nickel‐Catalyzed Cross‐Coupling of Arene‐ or Heteroarenecarbonitriles with Aryl‐ or Heteroarylmanganese Reagents through C?CN Bond Activation

The nickel‐catalyzed cross‐coupling reaction of arene‐ or heteroarenecarbonitriles with aryl‐ or heteroarylmanganese reagents via C CN bond activation has been developed. Both electron‐rich and electron‐deficient nitriles can be employed as the electrophilic substrates. The reaction tolerates a range of functional groups and aromatic heterocycles.     

Magnetically Retrievable Nano Crystalline Nickel Ferrite‐ Catalyzed Aerobic,Ligand‐Free C?N,C?O and C?C Cross‐ Coupling Reactions for the Synthesis of a Diversified Library of Heterocyclic Molecules

A new nickel ferrite nano‐crystal‐catalyzed, ligand‐free strategy for the construction of C N, C O, and C C bonds is presented, in which easily available nitrogen and oxygen nucleophiles, aryl/heteroaryl halides and arylboronic acids are used for the cross‐coupling reactions. The reactions can be performed at low catalyst loadings with excellent functional group tolerance and chemoselectivity. A variety of functional groups are compatible with the reaction conditions, including nitro, methoxy, as well as acid‐ and base‐sensitive heteroaromatic groups. This unprecedented chemistry nicely complements classical methods for the N‐arylation of amines/heteroamines, the O‐arylation of phenols/hydroxycoumarins and biaryl/heteroaryl synthesis. The low cost, easy to handle nature and the simplicity of this catalytic system render the method competitive with comparable copper‐ and palladium‐based protocols which require the presence of sophisticated ligands. Nickel ferrite magnetic nanoparticles were prepared by a simple hydrothermal method and characterized by using XRD, TEM image, energy dispersive X‐ray analysis, XPS and FT‐IR. The easy recovery of the catalyst and high yield of the products make the protocol attractive, sustainable and economic. The catalyst was reused for five cycles with almost unaltered catalytic activity.

     

Rhodium(III)‐Catalyzed Direct C?H Olefination of Arenes with Aliphatic Olefins

A rhodium(III)‐catalyzed direct ortho C H bond olefination of arenes, including but not limited to benzamides, arylpyridines and indoles, with a variety of unactivated aliphatic olefins has been developed. In the presence of catalytic amounts of dichloro(pentamethylcyclopentadienyl)rhodium(III) dimer {[Cp*RhCl₂]₂}, copper(II) acetate monohydrate [Cu(OAc)₂⋅H₂O] and silver hexafluoroantimonate(V) (AgSbF₆), the coupling reaction occurred efficiently to afford the ortho‐olefinated linear products in good to excellent yields with high regio‐ and stereoselectivities, and a range of functional groups in both coupling partners is compatible with the reaction conditions. This protocol relies on the use of directing groups, and the addition of AgSbF₆ as additive is crucial for the catalysis. This new method expands the scope of rhodium(III)‐catalyzed direct C H bond olefination of arenes, and provides a rapid access to useful linear arylation products of unactivated olefins.

     

One‐Pot Tandem Palladium‐Catalyzed Decarboxylative Cross‐Coupling and C?H Activation Route to Thienoisoquinolines

Two experimental approaches to the synthesis of a scarcely reported biologically active thienoisoquinoline system are demonstrated. A 5‐step linear synthesis employing a palladium‐catalyzed decarboxylative cross‐coupling and functionalization sequence allowed for the preparation of a diverse range of substituted thienoisoquinoline systems. Alternatively the palladium‐catalyzed decarboxylative cross‐coupling and C H activation steps can be telescoped to produce a one‐pot reaction sequence that provides efficient access to aryl‐substituted thienoisoquinolines.

     

Palladium‐Catalyzed/Lewis Acid‐Promoted Alkene Dimerization and Cross‐Coupling with Alcohols via C?H Bond Activation

The cross‐couplings of alcohols to alkenes with the palladium/Lewis acid system are reported. This reaction occurs in a successive alkene dimerization, direct C H activation of alcohol and sp³ sp³ bond forming sequence via an interesting domino process.     

Iron‐Catalyzed C?H Fuctionalization of Indoles

An easily available iron catalyst was developed to accomplish the C H functionalization of indoles with α‐aryl‐α‐diazoesters in high yields under mild conditions. The asymmetric C H functionalization of indoles was also realized by using iron complexes of chiral spiro bisoxazolines with up to 78% ee.