Light-induced iodoperfluoroalkylation reactions of carbon–carbon multiple bonds in water

Perfluoroalkylation of Triarylamines by EDA Complexes and Ulterior Sensitized [6π]-Electrocyclization to Perfluoroalkylated Endo-Carbazoles. Mechanistic and Photophysical Studies

Blue LEDs-irradiation of a mixture of N,N,N',N'-tetramethylethylenediamine (TMEDA) and perfluoroalkyl iodides (RF-I) - Electron Donor Acceptor (EDA)-complex - in the presence of triphenylamines (TPAs) in an aqueous solvent mixture afforded mono-perfluoroalkylated triphenylamines (RF-TPA) in good yields. These RF-TPA were further subjected to acetone-sensitized [6π]-electrocyclization at 315 nm-irradiation affording exclusively perfluoroalkylated endo-carbazole derivatives (RF-CBz) in quantitative yields. Mechanistic studies and photophysical properties of products are studied.

Photocatalyzed Perfluoroalkylation of Endoglycals

The visible light-induced perfluoroalkyl (RF) radical reactions on peracetylglycals derived from hexoses and pentoses (galactal, glucal, arabinal, and xylal derivatives) were investigated. Various photocatalysts and perfluoroalkyl iodides (RF-I) were employed as sources of RF radicals with LEDs as the irradiation source. Particularly noteworthy was the use of an Iridium photocatalyst, Ir[dF(CF3)ppy]2(dtbpy))PF6, which yielded two distinct product types when applied to glucal. On the one hand, the 2-RF-substituted glucal was formed, a trend observed even when utilizing organic dyes as photocatalysts. On the other hand, the unexpected addition product, namely the 1-RF-2-iodo-α-manno-configured C-glycosyl derivative, was also obtained, as a result of a highly regioselective addition reaction of the RF moiety into the anomeric carbon, followed by attachment of the iodine atom on C-2 in axial disposition. This result contrasted with other radical reactions carried out on 2-unsubstituted glycals, where the incipient radical adds to C-2, generating a stabilized 1-glycosyl radical. The photocatalyzed radical perfluoroalkylations of peracetyl glycals derived from galactose, arabinose, and xylose all afforded the 2-RF-substituted glycals in good yields as a result of the expected vinylic substitution reaction. Mechanistic studies revealed that the 1-RF-2-iodo-α-manno-configured C-glycosyl derivatives arise from a radical chain reaction, whereas the 2-RF-substituted glycals proceed from inefficient chain processes.

Photoredox-Catalyzed and Silane-Mediated Hydrofluoromethylation of Unactivated Alkenes with Fluoroiodomethane in Water

The first hydrofluoromethylation of unactivated alkenes with fluoroiodomethane and hydrosilanes is developed by merging photoredox catalysis and silane-mediated deiodination processes. The key to the success of this reaction is the use of water as the solvent to enhance the activity of CH₂F radical toward unactivated alkenes.

Rose Bengal-photocatalyzed perfluorohexylation reactions of organic substrates in water. Applications to late-stage syntheses

The Rose Bengal-photocatalyzed perfluorohexylation of olefins, alkynes, and electron-rich aromatic compounds in water was achieved employing perfluorohexyl iodide as fluoroalkyl source and TMEDA as sacrificial donor under green LED irradiation. Alkenes and alkynes rendered products derived from the atom transfer radical addition (ATRA) pathway, and in the case of alkynes, exclusively as E-stereoisomers. These are the first examples of photocatalyzed ATRA reactions carried out excursively in water alone. The reactions of aromatic compounds under the current protocol in water present the advantage of employing a perfluoroalkyl iodide (C₆F₁₃-I) as source of perfluorohexyl radicals. Examples of photocatalytic late-stage incorporations of fluoroalkyl moieties into two commercial drugs of widespread use are reported.

Simple Synthesis of Fluorinated Ene-Ynes via In Situ Generation of Allenes

Fluorination of small molecules is a key route toward modulating reactivity and bioactivity. The 1,3 ene-yne functionality is an important synthon towards complex products, as well as a common functionality in biologically active molecules. Here, we present a new synthetic route towards fluorinated ene-ynes from simple starting materials. We employ gas chromatography-mass spectrometry analysis to probe the sequential eliminations necessary for this transformation and observe an allene intermediate. The ene-yne products are sufficiently fluorous to enable purification via fluorous extraction. This methodology will allow facile access to functional, fluorous ene-ynes.

Vinyl Iodide Containing Polymers Directly Prepared via an Iodo-yne Polymerization

Postpolymerization modifications are a prominent route for tuning polymer properties and diversifying materials. Thus, polymers containing robust chemical handles are desirable. Vinyl iodide functionality is commonly enlisted for selective transformations on small molecules, but these chemistries, while efficient enough for postpolymerization modifications, are less frequently performed on macromolecules due to limited methods to install vinyl iodide groups into polymers. Here, we present an iodo-yne polymerization involving diynes and diiodoperfluoroalkanes to facilely give semifluorinated polymers with vinyl iodide groups throughout the polymer chain. The iodo-yne polymerization yields polymers of at least 6 kDa while open to air in aqueous solvent. We demonstrate that the iodo-yne polymers can be modified at the vinyl iodide functionality via a variety of metal-catalyzed cross-coupling reactions. Additionally, the iodide can be eliminated to give electronically activated alkynes that can undergo cycloaddition with azides. Taken together, this work will push the current boundaries of functional polymers and assist in the development of modernized, smart materials.

Organic dye-photocatalyzed fluoroalkylation of heteroarene-N-oxide derivatives

A direct C_Het–H perfluoroalkylation reaction of heteroaromatic-N-oxides has been achieved. Acid-catalyzed transformation of the perfluoroalkylated-N-oxides leads to 2-(perfluoroalkyl)benzo[f][1,3]oxazepines. De-oxygenation of the perfluoroalkylated heteroaromatic-N-oxides affords a regioselective radical perfluoroalkylation protocol.

Light-mediated iodoperfluoroalkylation of alkenes/alkynes catalyzed by chloride ions: role of halogen bonding

A catalytic amount of chloride ions greatly facilitates the UVA-mediated iodoperfluoroalkylation of alkenes and alkynes.

Regio- and Stereoselective Radical Perfluoroalkyltriflation of Alkynes Using Phenyl(perfluoroalkyl)iodonium Triflates

A method for regio- and stereoselective anti-addition of the perfluoroalkyl and the triflate group of phenyl(perfluoroalkyl)iodonium triflates to alkynes is presented. The radical reaction uses cheap CuCl as a smart initiator and can be conducted in gram scale. The perfluoroalkyltriflated products are readily further functionalized, rendering this transformation valuable.

Aromatic radical perfluoroalkylation reactions

This account intends to cover recent literature on radical perfluoroalkylation reactions of aromatic nuclei in organic and aqueous media. Emphasis will be placed on radical aromatic perfluoroalkylation reactions in water or aqueous media, with the aim of exploring aromatic radical reactivity in a benign environment.