Diaryliodonium Triflates Research Articles

Selective Preparation of Pyrrolo[2,3‐c]tetrahydroquinolines and Indolo[3,2‐c]tetrahydroquinolines through N‐Arylation/Cycloaddition/Rearrangement Annulation Reactions of Alkynyl‐Tethered Oximes with Diaryliodonium Salts

We describe a selective preparation of a variety of functionalized pyrrolo[2,3‐c]tetrahydroquinolines and indolo[3,2‐c]tetrahydroquinolines in 40‐82% and 40‐80% yields from alkynyl‐tethered oximes with diaryliodonium triflates, respectively. The one‐pot reaction underwent N‐arylation, intramolecular [3+2] cycloaddition, selective [1.3] or [3,3]‐rearrangement of N‐O bond in total three steps. Experimental studies revealed that EtOAc solvent and copper(II)‐catalyst played crucial roles on the formation of these two tetrahydroquinoline scaffolds. Moreover, these two tetrahydroquinoline scaffolds could be converted into various tetrahydroquinoline building blocks by further transformations.

Synthesis of N-acyl carbazoles, phenoxazines and acridines from cyclic diaryliodonium salts.

N-Acyl carbazoles can be efficiently produced through a single-step process using amides and cyclic diaryliodonium triflates. This convenient reaction is facilitated by copper iodide in p-xylene, using the commonly found activating ligand diglyme. We have tested this method with a wide range of amides and iodonium triflates, proving its versatility with numerous substrates. Beyond carbazoles, we also produced a variety of other N-heterocycles, such as acridines, phenoxazines, or phenazines, showcasing the robustness of our technique. In a broader sense, this new method creates two C-N bonds simultaneously based on a mono-halogenated starting material, thus allowing heterocycle formation with diminished halogen waste.

Novel electron donor-acceptor (EDA) complex promoted arylation of 2-oxo-2H-chromene-3-carbonitriles under visible light irradiation.

An efficient and operationally simple photochemical method has been demonstrated under transition metal-free, photocatalyst-free, and oxidant-free conditions. In recent times, diaryliodonium salts have become one of the most popular arylating sources under photoinduced conditions. Herein, we developed a visible light induced arylation of heterocycles using an EDA complex that is formed in situ from 2,6-lutidine and diaryliodonium triflate. Under light irradiation, the EDA complex generates the aryl radical that undergoes addition with 2-oxo-2H-chromene-3-carbonitriles via an SET process. This method serves as an effective tool to access biologically active and pharmaceutically relevant coumarin scaffolds.

Organophotoredox-Catalyzed Arylation and Aryl Sulfonylation of Morita-Baylis-Hillman Acetates with Diaryliodonium Reagents.

We report an organophotoredox-catalyzed stereoselective allylic arylation of MBH acetates with a palette of diaryliodonium triflates (DAIRs) to provide the corresponding trisubstituted alkenes in moderate to good yields. The method could be extended to three-component coupling involving 1,4-diazabicyclo[2.2.2]octane bis(sulfur dioxide) adduct (DABSO) as a sulfur dioxide surrogate for the synthesis of biologically relevant allylic sulfones. Both of these reactions were carried out under mild conditions featuring broad scope, robustness, and appreciable functional group tolerance.

Copper and In Situ-Generated Triflic Acid Relay-Promoted Four-Component Cascade Reaction for the Construction of Polysubstituted Cycloguanidines

An unprecedented copper and in situ-generated triflic acid relay-promoted four-component cascade reaction of cyanamides, diaryliodonium triflates, propargylic amines, and H2O was established for rapid and concise construction of diverse five-membered cycloguanidines. Copper-catalyzed guanidination/intramolecular hydroamination and in situ-generated HOTf-accelerated hydration proceeded sequentially with high level of chemoselectivity and regioselectivity, and six new bonds were simultaneously built in high yields. Thus, diaryliodonium triflates served not only as an arylation reagent but also as an internal acid promoter, establishing an alternative strategy for highly efficient utilization of diaryliodonium trifates.

Synthesis of Tetrahydrofurans and Pyrrolidines by Copper-Catalyzed Oxy/Aminoarylation of Alkenes.

An efficient copper-catalyzed inter/intramolecular oxy/aminoarylation of γ-hydroxy/aminoalkenes with diaryliodonium triflates is reported. Simple activation of these arylating agents with copper(II) triflate in dichloromethane triggers a smooth activation of the alkene, which is simultaneously trapped by the internal nucleophile, yielding, depending upon its nature, a range of highly substituted tetrahydrofurans and pyrrolidines. The cyclization was moreover found to be stereospecific, with diastereoisomeric alkenes yielding diastereoisomers of the cyclized product, and could be extended to oxyalkynylation.

Copper-catalyzed tandem cyclization/arylation of α,β-alkynic hydrazones with diaryliodonium salts: synthesis of N-arylpyrazoles.

A copper-catalyzed efficient method for the synthesis of a diverse variety of substituted N-aryl pyrazoles from readily available α,β-alkynic N-tosyl hydrazones and diaryliodonium triflates is realized. This one-pot multi-step methodology features a broad scope with good yields, scalability, and appreciable functional group tolerance. Detailed control experiments reveal that the reaction proceeds through tandem cyclization/deprotection/arylation events where the copper catalyst plays a distinct role.

Visible light photoredox-catalyzed arylative cyclization to access benzimidazo[2,1-a]isoquinolin-6(5H)-ones.

A photoredox-catalyzed arylative radical cascade involving N-acryloyl-2-arylbenzoimidazoles and diaryliodonium triflates leading to the formation of a broad array of pharmaceutically important arylated-benzimidazo[2,1-a]isoquinolin-6(5H)-ones is described. Importantly, the synthesized benzimidazoisoquinolinones are amenable for further synthetic manipulation and allowed efficient access to benzimidazo-fused polycyclic heterocycles.

Visible Light Photoredox-Catalyzed Direct C-H Arylation of Quinoxalin-2(1H)-ones with Diaryliodonium Salts.

A photoredox-catalyzed direct arylation of quinoxalin-2-(1H)-ones using diaryliodonium triflates as the convenient, stable, and cheap aryl source is described. A broad variety of quinoxalin-2-(1H)-ones are shown to react with structurally and electronically diverse diaryliodonium triflates, allowing efficient access to a wide variety of pharmaceutically important 3-arylquinoxalin-2-(1H)-ones. The presented method is attractive with regard to operational simplicity, mild conditions, broad scope, scalability, and high functional group tolerance.

One-Pot Synthesis of Heteroatom-Bridged Cyclic Diaryliodonium Salts.

Two one-pot procedures for the construction of O- and N-bridged diaryliodonium triflates are described. An effective aryne-mediated arylation of o-iodophenols and -sulfonamides provides diarylether and diarylamine intermediates, which are subsequently oxidized and cyclized to the corresponding diaryliodaoxinium and -iodazinium salts. Different derivatizations were applied to demonstrate their capacity as useful building blocks and gain a deeper understanding toward the general reactivity of these underdeveloped but potentially highly useful compounds.

Multicomponent Synthesis of Biologically Relevant S-Aryl Dithiocarbamates Using Diaryliodonium Salts.

A transition-metal-free one-pot three-component annulation between diaryliodonium triflates, cyclic and acyclic aliphatic amines, and carbon disulfide providing a convenient and efficient access to biologically relevant S-aryl dithiocarbamates is developed. The reaction does not require metal, base, or any other additive and operates under mild and ambient conditions. This methodology is robust, scalable, and exhibits a broad substrate scope. The in silico analysis revealed that the majority of the compounds have a drug-likeness and good ADMET characteristics.

Practical synthesis of diaryliodonium(iii) triflates using ArI(OAc)2/TfOH/MeCN reaction system

Diaryliodonium(iii) triflates were synthesized in a safe manner by the reaction of aryliodine(iii) diacetates ArI(OAc)2 with triflic acid (TfOH) in MeCN under mild exothermic conditions. This method provides access to a variety of diaryliodonium(iii) triflates, including derivatives with two different aryl substituents, with high purity.

One-Pot Synthesis and Conformational Analysis of Six-Membered Cyclic Iodonium Salts.

Two one-pot procedures for the construction of carbon-bridged diaryliodonium triflates and tetrafluoroborates are described. Strong Brønsted acids enable the effective Friedel-Crafts alkylation with diversely substituted o-iodobenzyl alcohol derivatives, providing diphenylmethane scaffolds, which are subsequently oxidized and cyclized to the corresponding dibenzo[b,e]iodininium salts. Based on NMR investigations and density functional theory (DFT) calculations, we could verify the so-far-undescribed existence of two stable isomers in cyclic iodonium salts substituted with aliphatic side chains in the carbon bridge.

CuO‐Catalyzed 1,3‐Addition of Diaryliodonium Triflates to Diazo Esters for the Stereoselective Synthesis of Triflate‐Substituted β‐Aryloxyl Acrylates

CuO‐catalyzed 1,3‐addition of diaryliodonium triflates to diazo esters was realized. This new strategy forms a series of triflate‐substituted β‐aryloxyl acrylate compounds with good tolerance of functional groups and excellent regioselectivity. Mild reaction conditions are enough, and strong acids or bases are not required. Easy manipulation and good step‐economy are further advantages. The alkenyl triflate products can be further modified via cross‐coupling reactions to generate derivatized products.

Pd-Catalyzed Arylation of α-Amino Esters with Diaryliodonium Triflates

Pd-Catalyzed Arylation of α-Amino Esters with Diaryliodonium Triflates

β-Selective Glycosylation by Using O-Aryl-Protected Glycosyl Donors.

New glycosyl donors have been developed that contained several para-substituted O-aryl protecting groups and their stereoselectivity for the glycosylation reaction was evaluated. A highly β-selective glycosylation reaction was achieved by using thioglycosides that were protected by 4-nitrophenyl (NP) groups, which were introduced by using the corresponding diaryliodonium triflate. Analysis of the stereoselectivities of several glycosyl donors indicated that the β-glycosides were obtained through an SN 2-type displacement from the corresponding α-glycosyl triflate. The NP group could be removed by reduction of the nitro group and acylation, followed by oxidation with ceric ammonium nitrate (CAN).

Free Amino Group-Directed γ-C(sp3)-H Arylation of α-Amino Esters with Diaryliodonium Triflates by Palladium Catalysis.

Free amino group-directed C(sp3)-H functionalization of aliphatic amines is a fundamental challenge in synthetic organic chemistry. Also, the NH2-directed C(sp3)-H functionalization of α-amino acids and their derivatives remains barely explored. With palladium as the catalyst and Ag2O as the additive, we developed the first NH2-directed γ-C(sp3)-H arylation of α-amino esters with diaryliodonium triflates for the construction of synthetically useful γ-aryl-α-amino esters, and the result of the KIE study suggested that the catalytic reaction involved an irreversible C-H cleavage as the rate-determining step.

Efficient N-arylation of azole compounds utilizing selective aryl-transfer TMP-iodonium(III) reagents

It was determined that diaryliodonium(III) triflates bearing a trimethoxybenzene (TMP) auxiliary are more reactive than the reported selective aryl-transfer iodonium salts in the N-arylation of benzimidazoles and other types of azole compounds under catalytic conditions. The TMP-iodonium(III) salts can thus effectively facilitate the reaction at 50 °C or below, producing the corresponding N-arylated biaryls without the formation of TMP-derived coupling byproducts. Utilization of this TMP reagent under mild conditions would prevent the underlying problem of participation of the auxiliary group in the coupling reactions, which is observed while using the iodonium(III) salts that require elevated temperatures.

Synthesis of Dibenzofurans from Cyclic Diaryliodonium Triflates and Water via Oxygen-Iodine Exchange Approach.

An efficient synthesis of a variety of dibenzofuran derivatives via Cu-catalyzed cyclization diaryliodonium salts in water is achieved. Various dibenzofuran derivatives could be obtained in good to excellent yields via this oxygen–iodine exchange approach. A concise synthesis of organic semiconducting material molecule has been achieved using this method.

Introduction of 4-Chlorophenyl: A Protecting Group for the Hydroxy Function

4-Chlorophenyl ether was utilized as a new protecting group for the hydroxy function. This group was readily introduced to a sugar hydroxy group by using diaryliodonium triflate. Regioselective introduction of this protecting group at the vicinal cis-diol was achieved by using a copper catalyst and diaryliodonium triflate. This protecting group is stable under the Lewis acidic conditions of glycosylation, but it can be readily removed by the initial conversion into the corresponding 4-methoxyphenyl ether with use of a Pd catalyst, followed by oxidation with ammonium cerium (IV) nitrate [(NH4)2Ce(NO3)6] (CAN).