Herein we disclose a deoxyfluorination of alcohols with an electrophilic fluorine source via visible-light photoredox catalysis. This radical-mediated C–F coupling is capable of fluorinating ...secondary and tertiary alcohols efficiently, complementing previously reported nucleophilic deoxyfluorination protocols.
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Herein we disclose a deoxyfluorination of alcohols with an electrophilic fluorine source via visible-light photoredox catalysis. This radical-mediated C–F coupling is capable of fluorinating ...secondary and tertiary alcohols efficiently, complementing previously reported nucleophilic deoxyfluorination protocols.
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•C3-Fluoroalkylated chlorophylls-a were prepared via deoxygenative fluorination.•Their absorption and emission bands were red-shifted from those of 3-alkyl-chlorins.•The red-shifts of ...their maxima were dependent on the fluorination degree.•The fluorescence emission enhanced and elongated with an increase in fluorination.•The C31,C32-fluorination finely tuned their optical properties in dichloromethane.
Methyl pyropheophorbides-a possessing a variety of fluoroalkyl groups at the 3-position were prepared via deoxyfluorination or deoxofluorination from naturally occurring chlorophyll-a. The synthetic C3-fluoroalkylated chlorins exhibited monomeric visible absorption spectra in dichloromethane. Their Qx/Qy absorption bands were red-shifted from those of the nonfluorinated counterparts. The red-shift values were dependent on the fluorination degree in the 3-alkyl group. The redmost Qy absorption and main fluorescence emission maxima gradually moved to longer wavelengths by fluorination and trifluoromethylation at the 31-position: λabs/λem = 655/659 nm (3-methyl-chlorin) < 676/679 nm (3-perfluoroethyl-chlorin). The substitutions similarly enhanced their fluorescence emission quantum yields and elongated their lifetimes: Φem/τem = 18.0%/6.1 ns (3-methyl-chlorin) < 21.5%/7.3 ns (3-perfluoroethyl-chlorin). The fluorination in the peripheral 3-substituent could finely tune the optical properties of the core chlorin chromophores.
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•Mainly three recent methods described for carbamoyl fluoride synthesis.•In situ-generated difluorocarbene reacts with hydroxylamines.•Difluorophosgene converts amines and ...isothiocyanates to carbamoyl fluorides.•Deoxyfluorination reagents convert carbamates obtained by CO2 uptake to carbamoyl fluorides.
This digest article summarizes the recent advances made for the synthesis of carbamoyl fluoride derivatives. Herein are highlighted several efficient methodologies. The scope of amine starting material encompasses hydroxylamines, isothiocyanates as well as secondary amines. The main strategies toward efficient methods to access carbamoyl fluorides are based on the in situ formation of difluorophosgene or the use of carbon dioxide in conjunction with deoxyfluorination reagents.
The activation of SF6, a potent greenhouse gas, under metal‐free and visible light conditions is reported. Herein, mechanistic investigations including EPR spectroscopy, NMR studies and cyclic ...voltammetry allowed the rational design of a new fluorinating reagent which was synthesized from the 2‐electron activation of SF6 with commercially available TDAE. This new SF5‐based reagent was efficiently employed for the deoxyfluorination of CO2 and the fluorinative desulfurization of CS2 allowing the formation of useful fluorinated amines. Moreover, for the first time we demonstrated that our SF5‐based reagent could afford the mild generation of Cl‐SF5 gas. This finding was exploited for the chloro‐pentafluorosulfanylation of alkynes and alkenes.
A new reagent has been designed through 2‐electron activation of SF6 with commercially available tetrakis(dimethylamino)ethylene (TDAE) under blue LED irradiation. The versatility of this new SF5‐based reagent has been demonstrated for the deoxyfluorination of CO2 and the fluorinative desulfurization of CS2 affording useful fluorinated amines. Moreover, SF5Cl could be generated under mild conditions from reagent I allowing chloro‐pentafluorosulfanylation of alkenes and alkynes.
N-Tosyl-4-chlorobenzenesulfonimidoyl fluoride (SulfoxFluor) has emerged as a new fluorination reagent that can be used in the rapid deoxyfluorination of various alcohols. We disclose in this article ...a general and practical method for the preparation of SulfoxFluor and its adaption to a large scale. Starting from readily available 4-chlorobenzenesulfonyl chloride, chloramine-T trihydrate, and potassium fluoride, SulfoxFluor was prepared on a hectogram scale in 63% overall yield with simple purification techniques. The use of chloramine-T trihydrate (instead of anhydrous chloramine-T) is a significant improvement over previous work, which streamlines the process and avoids the risk of explosion during drying or heating. This research not only establishes a reliable method for the scale-up synthesis of SulfoxFluor but also provides an insight into the imidation of sulfinyl chlorides with chloramine-T in the presence of water.
We report the development of a deoxyfluorination protocol using sulfur tetrafluoride (SF4) as a reagent to prepare organofluorine compounds in continuous flow mode. The method uses mild conditions, ...without the use of HF, which provides an improved safety profile. The methodology was applied to successfully convert various alcohols, aldehydes, and carboxylic acids to their corresponding fluorinated compounds. Advantages of the protocol include the tolerance of protecting groups, high enantioselective control, and easy incorporation of inline reaction monitoring.
The deoxyfluorination of alcohols is a fundamentally important approach to access alkyl fluorides, and thus the development of shelf‐stable, easy‐to‐handle, fluorine‐economical, and highly selective ...deoxyfluorination reagents is highly desired. This work describes the development of a crystalline compound, N‐tosyl‐4‐chlorobenzenesulfonimidoyl fluoride (SulfoxFluor), as a novel deoxyfluorination reagent that possesses all of the aforementioned merits, which is rare in the arena of deoxyfluorination. Endowed by the multi‐dimensional modulating ability of the sulfonimidoyl group, SulfoxFluor is superior to 2‐pyridinesulfonyl fluoride (PyFluor) in fluorination rate, and is also superior to perfluorobutanesulfonyl fluoride (PBSF) in fluorine‐economy. Its reaction with alcohols not only tolerates a wide range of functionalities including the more sterically hindered alcoholic hydroxyl groups, but also exhibits high fluorination/elimination selectivity. Because SulfoxFluor can be easily prepared from inexpensive materials and can be safely handled without special techniques, it promises to serve as a practical deoxyfluorination reagent for the synthesis of various alkyl fluorides.
The deoxyfluorination of alcohols is a fundamentally important approach to access alkyl fluorides, and thus the development of shelf‐stable, easy‐to‐handle, fluorine‐economical, and efficient deoxyfluorination reagents is highly desirable. N‐tosyl‐4‐chlorobenzenesulfonimidoyl fluoride (SulfoxFluor) is a novel deoxyfluorination reagent that possesses all of the aforementioned merits.
A convenient method for deoxyfluorination of aromatic and aliphatic carboxylic acids with CF3SO2OCF3 in the presence of a suitable base at room temperature has been developed. The reaction allows a ...straightforward access to a variety of acyl fluorides and proves that CF3SO2OCF3 is an effective deoxyfluorination reagent for carboxylic acids. The method features simplicity, expeditiousness, high efficiency, ease of handling, good functional group tolerance, a wide range of substrates, excellent yields of products, compatibility of many amine initiators, use of environmentally friendly reagents, and effortless removal of byproducts. This reaction represents the first utilization of trifluoromethyl trifluoromethanesulfonate as a fluorination reagent.
Amine‐triggered deoxyfluorination of carboxylic acids with CF3SO2OCF3 is described. The reaction proceeds rapidly at room temperature under metal‐free conditions to form various acyl fluorides in up to 97 % yield. This protocol represents the first utilization of trifluoromethyl trifluoromethanesulfonate as a convenient and efficient fluorination reagent.
•The syntheses of aliphatic and aromatic acyl fluorides are described.•The highly active CuF species generated from CuCF3 is investigated.•Computational studies for copper fluoroalkyl intermediates ...are performed.
Trifluoromethyl copper (CuCF3), as a diverse fluorination reagent, has been widely used in trifluoromethylation, perfluoroalkylation, and difluorocarbene reactions. However, it has rarely been reported as a single fluorine source involved in nucleophilic fluorination reactions. This work describes a general strategy involving copper-mediated deoxyfluorination of redox-active esters to rapidly access various aliphatic and aromatic acyl fluorides. The highly active CuF species could be generated from either copper fluoride salts or CuCF3. A plausible mechanism of CuCF3 forming an F-CuCF2F5- intermediate and NHBC ester forming acyl fluoride has been derived from DFT calculations.
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