Simple and regioselective oxyiodination of aromatic compounds with ammonium iodide and Oxone®

The Versatile and Strategic O-Carbamate Directed Metalation Group in the Synthesis of Aromatic Molecules: An Update

The aryl O-carbamate (ArOAm) group is among the strongest of the directed metalation groups (DMGs) in directed ortho metalation (DoM) chemistry, especially in the form Ar-OCONEt2. Since the last comprehensive review of metalation chemistry involving ArOAms (published more than 30 years ago), the field has expanded significantly. For example, it now encompasses new substrates, solvent systems, and metalating agents, while conditions have been developed enabling metalation of ArOAm to be conducted in a green and sustainable manner. The ArOAm group has also proven to be effective in the anionic ortho-Fries (AoF) rearrangement, Directed remote metalation (DreM), iterative DoM sequences, and DoM-halogen dance (HalD) synthetic strategies and has been transformed into a diverse range of functionalities and coupled with various groups through a range of cross-coupling (CC) strategies. Of ultimate value, the ArOAm group has demonstrated utility in the synthesis of a diverse range of bioactive and polycyclic aromatic compounds for various applications.

Synthesis of Novel Nitro-Halogenated Aryl-Himachalene Sesquiterpenes from Atlas Cedar Oil Components: Characterization, DFT Studies, and Molecular Docking Analysis against Various Isolated Smooth Muscles

We report the synthesis of two novel halogenated nitro-arylhimachalene derivatives: 2-bromo-3,5,5,9-tetramethyl-1-nitro-6,7,8,9-tetrahydro-5H-benzo[7]annulene (bromo-nitro-arylhimachalene) and 2-chloro-3,5,5,9-tetramethyl-1,4-dinitro-6,7,8,9-tetrahydro-5H-benzo[7]annulene (chloro-dinitro-arylhimachalene). These compounds were derived from arylhimachalene, an important sesquiterpene component of Atlas cedar essential oil, via a two-step halogenation and nitration process. Characterization was performed using 1H and 13C NMR spectrometry, complemented by X-ray structural analysis. Quantum chemical calculations employing density functional theory (DFT) with the Becke3-Lee-Yang-parr (B3LYP) functional and a 6-31++G(d,p) basis set were conducted. The optimized geometries of the synthesized compounds were consistent with X-ray structure data. Frontier molecular orbitals and molecular electrostatic potential (MEP) profiles were identified and discussed. DFT reactivity indices provided insights into the compounds' behaviors. Moreover, Hirshfeld surface and 2D fingerprint analyses revealed significant intermolecular interactions within the crystal structures, predominantly H-H and H-O contacts. Molecular docking studies demonstrate strong binding affinities of the synthesized compounds to the active site of protein 7B2W, suggesting potential therapeutic applications against various isolated smooth muscles and neurotransmitters.

Efficient and sustainable laccase-catalyzed iodination of p-substituted phenols using KI as iodine source and aerial O2 as oxidant

The laccase-catalyzed iodination of p-hydroxyarylcarbonyl- and p-hydroxyarylcarboxylic acid derivatives using KI as iodine source and aerial oxygen as the oxidant delivers the corresponding iodophenols in a highly efficient and sustainable manner with yields up to 93% on a preparative scale under mild reaction conditions.

Advances in the direct iodination of aromatic compounds

Methods for the direct iodination of aromatic compounds are reviewed.

Cyanation of aromatic/vinylic boronic acids with α-cyanoacetates

A protocol is reported to achieve safe and convenient aromatic and vinylic cyanation of boronic acids (as well as halides) with α-cyanoacetates, avoiding the use of toxic cyanide salts.

Oxidative Acetoxylactonisation of Alkenoic Acids Using H2O2 in Acetic Acid Catalysed by KI

In the presence of a catalytic amount of KI in combination with H2O2, a convenient catalytic procedure has been developed for the direct preparation of acetoxylactones from alkenoic acids in acetic acid at room temperature which provides the corresponding cyclic products in good yields. This novel methodology mediated by an in situ generated hypervalent iodine intermediate extends the catalytic application of KI in organic synthesis.

Facile, efficient, and environmentally friendly α- and aromatic regioselective chlorination of toluene using KHSO5 and KCl under catalyst-free conditions

The nontoxic, green, safe, stable, and inexpensive reagents Oxone and KCl were employed in the non-catalyzed chlorination of toluene at room temperature.

Copper-catalyzed cyanation of aryl iodides with α-cyanoacetates via C–CN bond activation

A mild copper-catalyzed cyanation of aryl iodides using readily available and friendly α-cyanoacetates as the CN source is reported.

Novel Phosphoryloxylactonisation of Pentenoic Acids Mediated by Ammonium Iodide

Using ammonium iodide as a catalyst and m-chloroperbenzoic acid as the oxidant, a novel and efficient procedure has been developed for phosphoryloxylactonisation of alkenoic acids in CH3CN at room temperature, which provides the corresponding phosphoryloxylactones in good yields. In this protocol, it is proposed that ammonium iodide catalyst is first oxidised to hypoiodous acid, which reacts with the alkenoic acid to afford the corresponding iodolactone. Then, the iodolactone is further transformed into a hypervalent iodine intermediate by continuing oxidation, and finally the in situ generated active iodine species reacts with a diaryl phosphate to furnish the phosphoryloxylactone end product.

Iodide-catalyzed halocyclization/cycloaddition/elimination cascade reaction

An iodocyclization reaction of o-alkynylphenyl carboxaldehydes is reported that is truly catalytic with respect to the electrophilic iodine source. With a combination of tetrabutylammonium iodide (TBAI), Oxone as non-nucleophilic and easy to handle co-oxidant, and fluorinated protic solvents, highly substituted 1-naphthalenones could be prepared in high yields of up to 91%.

Copper-mediated selective cyanation of indoles and 2-phenylpyridines with ammonium iodide and DMF

Copper-mediated regioselective cyanation of indoles and 2-phenylpyridines was developed by using ammonium iodide and DMF as the combined source of a cyano unit under "Pd-free" conditions. Mechanistic studies indicate that the reaction of indoles proceeds through a two-step sequence: electrophilic initial iodination and then cyanation. The cyanation has a broad substrate scope, high functional group tolerance, and excellent regioselectivity.

A method for parallel solid-phase synthesis of iodinated analogues of the CB1 receptor inverse agonist rimonabant

A method for the parallel solid-phase synthesis (SPS) of iodinated analogues of Sanofi-Aventis' type 1 cannabinoid (CB1) receptor inverse agonist rimonabant (acomplia) has been developed. The method allows the synthesis of a range of C3 amide/hydrazide derivatives from a resin-bound C3 ester precursor. The C-Ge linkage to the Hypogel-200 resin is stable to the diversification conditions but allows ipso-iododegermylative cleavage using NaI/NCS even for the products containing the oxidatively labile hydrazide moiety.

Direct halogenation of organic compounds with halides using oxone in water — A green protocol

Direct bromination and iodination of various aromatic compounds with NaBr and NaI using oxone (2KHSO5·KHSO4·K2SO4) in water was accomplished successfully in high-to-excellent yields. The main benefit of this protocol is the performance of the reactions in water in the presence of a harmless oxidant without the use of any organic co-solvents. Using NaBr and NaI as the safe sources of halogens is another advantage of the protocol. This method is easily applicable to the large-scale operations. We have also applied this method successfully for the iodocyclization of an unsaturated alcohol and an unsaturated carboxylic acid.

Single-isomer iodochlorination of alkynes and chlorination of alkenes using tetrabutylammonium iodide and dichloroethane

The efficient formation of single-isomer, differentially halogenated alkenes and alkanes is described. These structures were generated by treatment of the appropriate alkyne or alkene with tetrabutylammonium iodide in refluxing dichloroethane. This process is highly selective as evidenced by control experiments using ICl. Treatment of the same alkenes and alkynes directly with iodine monochloride resulted in complex, inseparable mixtures of regio- and stereoisomers. Mechanistic studies indicated that the Bu4NI reaction most likely proceeded through the slow generation of ICl. Complexation of ICl with Bu4NI is also a key controlling element that leads to perfect regio-, chemo-, and stereoselectivity in these processes.

One-Pot Preparation of Arylalkynes by a Tandem Catalytic Iodination of Arenes and Palladium-Catalyzed Coupling of Iodoarenes with Terminal Alkynes

Iodination of activated arenes by air-oxidation is carried out in the presence of catalytic bismuth salts at room temperature. Subsequently, the formed iodoarenes react with terminal alkynes to give arylalkynes under a selected palladium-catalyzed coupling condition in the same pot.