Phenyl Iodonium Salts Research Articles

Copper-catalyzed reactions of α,β-unsaturated N-tosylhydrazones with diaryliodonium salts to construct N-arylpyrazoles and diaryl sulfones.

Herein, an economical copper-catalyzed reaction of α,β-unsaturated N-tosylhydrazones with diaryliodonium salts to construct both N-arylpyrazoles and diaryl sulfones has been developed. Both the p-toluenesulfonyl anion and the 3-arylpyrazole intermediates were formed in situ from N-tosylhydrazones. Subsequently, the former reacted rapidly with diaryliodonium salts to give diaryl sulfones and aryl iodide intermediates, and the latter reacted with aryl iodide to give N-arylpyrazoles under copper-catalyzed conditions. Using unsymmetrical mesityl phenyliodonium salts as substrates, mesityl p-toluenesulfide was obtained as the major product. This reaction took full advantage of the "waste" part of substrates to form an extra diaryl sulfone.

Investigation of Monocarbon Carboranes as Pendant Groups for Labeling Small Molecules with Astatine-211

The dianionic boron cage molecule closo-decaborate(2-) is being used as a pendant group to label monoclonal antibodies with the alpha-emitting radionuclide, astatine-211 (211At). While this works very well for antibody labeling, it appears that application of the same moiety for labeling small molecules can significantly alter blood clearance of biomolecule conjugates. As an example, in a murine model an 211At-labeled biotin derivative used in a cancer pretargeting approach clears the blood so rapidly that it fails to reach the antibodystreptavidin conjugate bound with tumor cells. Our hypothesis is that the dianionic nature of the astatinated pendant group facilitates rapid excretion of the biotin conjugate. Therefore we are investigating the use of another boron cage moiety, a monocarbon carborane, closo-1carba-nonadecaborate(1-) {referred to as closo-1-CB9H10} as an alternative 211At-labeling moiety. Two closo-CB9H10(1-) derivatives, 1-carboxyl-1-CB9H9, 1, and 1-p-benzoate-1-CB9H9, 2, were prepared following literature reports (Chem. Commun. 328-329,2004 & Dalton Trans. 3552-3561, 2004). Tetrafluorophenyl esters of the carboxylates in 1 & 2 were prepared and were reacted with an amine in a biotin-sarcosine derivative to provide biotin derivatives that contain the two anionic closo-CB9H9(1-) moieties. Electrophilic astatination reactions of the derivatives containing closo-CB9H9(1-) were found to be low yielding, even at elevated temperatures. To facilitate the astatination reactions, 10-substituted phenyl iodonium salts of 1 & 2, compounds 3 & 4, were prepared and astatination of those derivatives were evaluated using [211At]sodium astatide. While astatination occurred (up to 50%), it was noted that a new less lipophilic product was formed in the reaction, particularly at elevated temperatures. The labeling reactions of 1-p-benzoate-10-phenyl-iodonium-closo-CB9H8, 4, had fewer side products than 3, so that reagent was selected for our subsequent studies. Reactions conducted under the same conditions, but without 211At present, provided an opportunity to isolate and characterize the reaction side product. NMR and mass spectral data supported characterization of the compound as the 10-hydroxyl-1-p-benzoate-closoCB9H8, 5. Compound 5 is readily prepared from 4. Electrophilic astatination of 5 provided a single compound in ∼80% radiochemical yield, making it an attractive pendant group for small molecule labeling of 211At. Astatination studies are continuing with compounds 2, 4 and 5 to optimize the radiochemical yields, as are astatinations of biotin derivatives containing these moieties. Tissue biodistribution studies are planned to determine the in vivo stability of the 211At-labeled compounds. It should be noted that the use of the phenyliodonium intermediate allows introduction of 211At under nucleophilic non-oxidizing conditions, so this labeling method can be used for 211At-labeling of compounds that are sensitive to oxidizing (electrophilic) conditions.

A Modular Synthesis of 4-Aminoquinolines and [1,3] N-to-C Rearrangement to Quinolin-4-ylmethanesulfonamides.

A copper-catalyzed regiocontrolled three-component reaction afforded diversified 4-aminoquinolines using nitriles, diaryliodoniums, and ynamides. The C7-substituted regioisomers were formed regioselectively when meta-substituted phenyliodonium salts were used. [1,3] N-to-C rearrangement of the products to quinolin-4-ylmethanesulfonamides and simultaneous deprotection of benzyl and sulfonamide group were newly developed. Finally, antimalarial CK-2-68 was successfully prepared.

Tosyiate of ethyl 3-amino-2-phenyliodoniocrotonate: Synthesis, crystal structure, and synthesis of heterocyclic compounds based on it

Ethyl 3-aminocrotonate, when reacted with hydroxy(tosyloxy)iodobenzene, forms the tosylate of ethyl 3-amino-2-phenyliodoniocrotonate which crystallizes well in up to 80% yield. X-ray analysis confirms the structure of the phenyliodonium salt, revealing intramolecular and unusual intermolecular hydrogen bonds, stabilizing the compound in the crystalline state. Reaction with pyridine, its 4-substituted derivatives, and 4,4′-bipyridine yields tosylates of 2-pyridinio-substituted ethyl 3-aminocrotonates.1H NMR and IR spectra support formation of an intramolecular hydrogen bond for the E-isomer, and iodonium salts in the case of pyridinium salts for the Z-isomer. The UV spectra of the pyridinium salts show an intramolecular charge transfer band.

Photolysis of ((3-(Trimethylsilyl)propoxy)phenyl)phenyliodonium salts in the presence of 1-naphthol and 1-methoxynaphthalene

Direct photolysis of ((3-trimethylsilylpropoxy)phenyl)phenyliodonium salts with different counteranions (Cl(-), SbF(6)(-), and B(C(6)F(5))(4)(-)) in methanol leads to products by both heterolytic and homolytic processes. In the presence of 1-naphthol and 1-methoxynaphthalene, products formed by a heterolytic reaction disappear, suggesting an electron-transfer process occurs between excited 1-naphthol/1-methoxynaphthalene and the iodonium salts. In the case of 1-methoxynaphthalene, three phenylated methoxynaphthalene isomers are produced. These are produced as radical coupling products from the phenyl radical and 1-methoxynaphthalene radical cation.

ChemInform Abstract: Synthesis of (Z)‐1,2‐Dihalo‐1‐alkenes by the Reaction of (Z)‐(β‐ Halovinyl)phenyliodonium Salts with n‐Bu4NX or KX/CuX. Competitions Between Nucleophilic Vinylic Substitutions and Aromatic Substitutions.

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Synthesis of (Z)-1,2-Dihalo-1-alkenes by the Reaction of (Z)-(β-Halovinyl)phenyliodonium Salts with n-Bu4NX or KX/CuX. Competitions between Nucleophilic Vinylic Substitutions and Aromatic Substitutions

Abstract Nucleophilic vinylic substitutions of (Z)-(β-halovinyl)phenyliodonium salts with tetrabutylammonium halides proceed in a stereoselective manner with retention of configuration yielding vicinal (Z)-vinyl dihalides. This reaction competes with nucleophilic aromatic substitutions. Similar competition was observed in the reactions with potassium halides/cuprous halides.

Alkoxy‐substituted diaryliodonium salt cationic photoinitiators

AbstractThis paper describes the synthesis and characterization of a series of (4‐alkoxyphenyl)phenyliodonium salts which are excellent photo‐ and thermal‐initiators for the cationic polymerization of vinyl and heterocyclic monomers. These compounds are easily prepared by straightforward synthetic techniques and display very good solubility and photoresponse characteristics which make them especially attractive for use in UV curing applications. Those compounds with alkoxy chains of eight carbons and longer are essentially nontoxic.