Unsymmetrical Diaryliodonium Salts Research Articles

Base-promoted synthesis of diarylsulfones from sulfonyl hydrazines and diaryliodonium salts.

An efficient and concise method for the synthesis of diverse substituted sulfones was developed with high selectivity. Using n-PrOH as the solvent, diaryl sulfones are formed even on a gram scale via metal-free coupling from sulfonyl hydrazines with symmetrical or unsymmetrical diaryliodonium salts.

Copper‐Catalyzed Selective N‐Arylation of Oxadiazolones by Diaryliodonium Salts

AbstractHere, we report the method for copper‐catalyzed N‐arylation of diverse oxadiazolones by diaryliodonium salts under mild conditions in high yields (up to 92%) using available CuI as a catalyst. The developed method allows utilizing both symmetric and unsymmetric diaryliodonium salts bearing auxiliary groups such as 2,4,6‐trimethoxyphenyl (TMP). We found that the steric effects in aryl moieties determined the chemoselectivity of N‐ and O‐arylation of the 1,2,4‐oxadiazol‐5(4H)‐ones. Mesityl‐substituted diaryliodonium salts demonstrated the high potential as a selective arylation reagent. The structural study suggests that steric accessibility of N‐atom in 1,2,4‐oxadiazol‐5(4H)‐ones impact to arylation with sterically hindered diaryliodonium salts. The synthetic application of proposed method was also demonstrated on selective arylation of 1,3,4‐oxadiazol‐2(3H)‐ones and 1,2,4‐oxadiazole‐5‐thiol.magnified image

Transition Metal-Free N-Arylation of Amino Acid Esters with Diaryliodonium Salts.

A transition metal‐free approach for the N‐arylation of amino acid derivatives has been developed. Key to this method is the use of unsymmetric diaryliodonium salts with anisyl ligands, which proved important to obtain high chemoselectivity and yields. The scope includes the transfer of both electron deficient, electron rich and sterically hindered aryl groups with a variety of different functional groups. Furthermore, a cyclic diaryliodonium salt was successfully employed in the arylation. The N‐arylated products were obtained with retained enantiomeric excess.

Copper-Catalyzed C–H Arylation of Fused-Pyrimidinone Derivatives Using Diaryliodonium Salts

Copper-catalyzed Csp2–Csp2 bond forming reactions through C–H activation are still one of the most useful strategies for the diversification of heterocyclic moieties using various coupling partners. A catalytic protocol for the C–H (hetero)arylation of thiazolo[5,4-f]quinazolin-9(8H)-ones and more generally fused-pyrimidinones using catalyst loading of CuI with diaryliodonium triflates as aryl source under microwave irradiation has been disclosed. The selectivity of the transfer of the aryl group was also disclosed in the case of unsymmetrical diaryliodonium salts. Specific phenylation of valuable fused-pyrimidinones including quinazolinone are provided. This strategy enables a rapid access to an array of various (hetero)arylated N-containing polyheteroaromatics as new potential bioactive compounds.

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.

Palladium-Catalyzed Intermolecular Arylcarbonylation of Unactivated Alkenes: Incorporation of Bulky Aryl Groups at Room Temperature.

A palladium-catalyzed intermolecular arylcarbonylation of unactivated alkenes has been developed. Unsymmetrical diaryliodonium salts (DAISs) were used as arylation reagents, the bulky aryl group (ArL ) of which was exclusively incorporated into the arylcarbonylated products, which contained the ArL group and a carboxylic ester group at the α- and β-carbon position, respectively, of the original terminal C-C double bond. The reaction features excellent chemo- and regioselectivity, high functional-group tolerance, and very mild reaction conditions.

Palladium‐Catalyzed Intermolecular Arylcarbonylation of Unactivated Alkenes: Incorporation of Bulky Aryl Groups at Room Temperature

AbstractA palladium‐catalyzed intermolecular arylcarbonylation of unactivated alkenes has been developed. Unsymmetrical diaryliodonium salts (DAISs) were used as arylation reagents, the bulky aryl group (ArL) of which was exclusively incorporated into the arylcarbonylated products, which contained the ArL group and a carboxylic ester group at the α‐ and β‐carbon position, respectively, of the original terminal C−C double bond. The reaction features excellent chemo‐ and regioselectivity, high functional‐group tolerance, and very mild reaction conditions.

N1-Arylation of 1,4-Benzodiazepine-2-ones with Diaryliodonium Salts

A library of N 1-arylated 5-phenyl-1,3-dihydro-2 H -1,4-benzodiazepin-2-ones has been synthesized starting with unsymmetrical diaryliodonium salts using aqueous ammonia as a base. This can also be applied to a similar 1,3,4-benzotriazepin-2-one derivative.

Aryl Transfer Selectivity in Metal-Free Reactions of Unsymmetrical Diaryliodonium Salts.

Aromatic rings are found in a wide variety of products, including pharmaceuticals, agrochemicals, and functional materials. Diaryliodonium salts are new reagents used to transfer aryl groups under both metal-free and metal-catalyzed reactions and thereby synthesize arene-containing compounds. This minireview focuses on recent studies in selective aryl transfer reactions from unsymmetrical diaryliodonium salts under metal-free conditions. Reactions reported from 2007 to 2017, which represents a period of significant growth in diaryliodonium salt chemistry, are presented and organized by the type of reactive intermediate formed in the reaction. Specifically, reactions involving λ3 -iodane, λ3 -iodane radical anions, aryl radicals, and arynes are discussed. Chemoselectivity trends in aryl transfer are compared and contrasted across reaction intermediates and translation to potential auxiliaries are posited.

One-Pot Synthesis of Unsymmetric Diaryliodonium Salts from Iodine and Arenes.

The first synthesis of unsymmetric diaryliodonium salts directly from iodine and arenes is presented. The methodology provides diaryliodonium salts with the trimethoxyphenyl (TMP) moiety as dummy group. The protocol avoids the customary use of iodoarenes, which can be both expensive and toxic. Excess reagents are not required, and the reactions are performed under mild conditions. O-Arylations with these TMP salts were demonstrated to be highly chemoselective.

Domino N‐/C‐Arylation via In Situ Generation of a Directing Group: Atom‐Efficient Arylation Using Diaryliodonium Salts

AbstractBoth aryl components of diaryliodonium salts can be used in a domino one‐pot reaction via in situ generation of a directing group. A number of heterocycles undergo N‐arylation which is followed by ruthenium‐catalyzed C‐arylation. Notably the reaction extends well to unsymmetrical diaryliodonium salts with a number of highly selective examples shown.

Domino N-/C-Arylation via In Situ Generation of a Directing Group: Atom-Efficient Arylation Using Diaryliodonium Salts.

Both aryl components of diaryliodonium salts can be used in a domino one-pot reaction via in situ generation of a directing group. A number of heterocycles undergo N-arylation which is followed by ruthenium-catalyzed C-arylation. Notably the reaction extends well to unsymmetrical diaryliodonium salts with a number of highly selective examples shown.

Unsymmetrical Diaryliodonium Salts as Aryne Synthons: Renaissance of a C–H Deprotonative Approach to Arynes

A regio- and chemoselective C–H deprotonative strategy toward arynes is described that employs a hypervalent iodine leaving group. The unsymmetrical aryl(mesityl)iodonium salts used as aryne precursors are readily synthesized from commercially available aryl iodide and arylboronic acid building blocks. The bases LiHMDS and NaOt-Bu engage the diaryliodonium salts in a deprotonation event at an aromatic C–H bond and the transient arynes react in cycloaddition reactions with furan and benzyl azide or nucleophilic addition reaction with alicyclic amines. The auxiliary component of aryl(auxiliary)iodonium salts can be sterically tuned to influence the regioselectivity of the C–H deprotonation event for meta-substituted aryl groups. 1 Introduction 2 Iodonium Salts as Aryne Precursors 3 Reaction Discovery and Optimization 4 Reaction Scope 5 Auxiliary-Controlled Regioselective Deprotonation 6 Beyond Cycloaddition with Furan 7 Conclusions and Outlook

ChemInform Abstract: A Review on the Advancement of Ether Synthesis from Organic Solvent to Water

AbstractReview: 106 refs.

Understanding and Exploitation of Neighboring Heteroatom Effect for the Mild N-Arylation of Heterocycles with Diaryliodonium Salts under Aqueous Conditions: A Theoretical and Experimental Mechanistic Study.

The mechanism of arylation of N-heterocycles with unsymmetric diaryliodonium salts is elucidated. The fast and efficient N-arylation reaction is interpreted in terms of the bifunctionality of the substrate: The consecutive actions of properly oriented Lewis base and Brønsted acid centers in sufficient proximity result in the fast and efficient N-arylation. The mechanistic picture points to a promising synthetic strategy where suitably positioned nucleophilic and acidic centers enable functionalization, and it is tested experimentally.

ChemInform Abstract: Base Mediated Synthesis of Alkyl‐Aryl Ethers from the Reaction of Aliphatic Alcohols and Unsymmetric Diaryliodonium Salts.

AbstractThe title method is characterized by operational simplicity, broad substrate scope, and mild reaction conditions.

Transition-Metal-Free N-Arylation of Pyrazoles with Diaryliodonium Salts.

A new synthetic method was developed for the N-arylation of pyrazoles using diaryliodonium salts. The transformation does not require any transition-metal catalyst and provides the desired N-arylpyrazoles rapidly under mild reaction condition in the presence of aqueous ammonia solution as a mild base without the use of inert atmosphere. The chemoselectivity of unsymmetric diaryliodonium salts was also explored with large number of examples.

Base Mediated Synthesis of Alkyl-aryl Ethers from the Reaction of Aliphatic Alcohols and Unsymmetric Diaryliodonium Salts.

The base mediated coupling of aliphatic alcohol pronucleophiles with unsymmetric diaryliodonium salt electrophiles is described. This metal-free reaction is operationally simple, proceeds at mild temperature, and displays broad substrate scope to generate industrially important alkyl-aryl ethers in moderate to excellent yield. The synthetic utility of these reactions is demonstrated, and aspects of sustainability are highlighted by the use of unsymmetric aryl(mesityl)iodonium arylating reagents.

Synthesis of Diaryliodonium Salts Having Pentafluorosulfanylarenes and Their Application to Electrophilic Pentafluorosulfanylarylation of C-, O-, N-, and S-Nucleophiles.

Novel reagents for the electrophilic introduction of pentafluorosulfanyl (SF5) arenes into target molecules are disclosed. Unsymmetrical diaryliodonium salts 1 having SF5-arenes were synthesized by a one-pot process from iodo-SF5-benzenes 2 in good yields. The SF5-aryliodonium salts 1 were found to be efficient for the electrophilic SF5-arylation of carbon and heterocentered nucleophiles to furnish the corresponding substituted SF5-arenes in good to high yields.

One-pot synthesis of aryl sulfones from organometallic reagents and iodonium salts.

A transition-metal-free arylation of lithium, magnesium, and zinc sulfinates with diaryliodonium salts is described. The sulfinic acid salts were prepared from the reaction of the corresponding organometallic reagents and sulfur dioxide. Combination of the three single steps (preparation of the organometallic compound, sulfinate formation, and arylation) leads to a one-pot sequence for the synthesis of aryl sulfones from simple starting materials. The chemoselectivity of unsymmetrical diaryliodonium salts has been investigated. Potential and limitations of this method will be discussed.