Search

A highly efficient method for controllable double CF 2 -insertion into pentafluorophenylcopper species using TMSCF 3 as difluoromethylene source has been developed. The newly generated fluoroalkylcopper(i) species, C 6 F 5 CF 2 CF 2 Cu, shows good reactivity towards a myriad of structurally diverse aryl, heteroaryl and alkenyl iodides. This protocol is easy to handle, ready to scale up and applicable for the synthesis of relative complex molecules, thus providing a convenient method for facile access to tetrafluoroethylene-bridged structures., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

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., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

An efficient method for the selective C-difluoromethylation of carbon acids with the reagent TMSCF 2 Br has been developed. A variety of structurally diverse sp 3 - and sp-hybridized carbon nucleophiles, including esters, amides, fluorenes, terminal alkynes, β-ketoesters, malonates, and other activated C-H nucleophiles, could be efficiently and selectively transformed into the corresponding C-difluoromethylated products under mild conditions. This protocol is also effective for the late-stage difluoromethylation of pharmaceutically relevant molecules and can be readily scaled up. Moreover, ambident substrates with more than one reactive site towards difluorocarbene can be difluoromethylated orthogonally using TMSCF 2 Br., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Soft, elastomeric, non-tacky polymer networks are synthesized by reversible deactivation radical polymerization (RDRP). First, the pristine, structurally tailored and engineered macromolecular (STEM) networks are synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization and incorporated an atom transfer radical polymerization (ATRP) inimer into the network. Subsequently, poly(n-butyl acrylate) (PBA) and/or poly(octafluoropentyl acrylate) (POFPA) side chains are grafted from the network by photo-induced ATRP. These low glass transition temperature side chains produced soft materials (E = 104-178 kPa). However, only the POFPA-containing networks are also non-tacky. The fluorine content and material properties are investigated by dynamic mechanical analysis, elemental analysis, spectroscopy, and contact angle measurements., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A highly efficient copper-mediated aromatic pentafluoroethylation method using TMSCF 3 as the sole fluoroalkyl source is described. The reaction proceeds by a key C 1 to C 2 process, that is, the generation of CuCF 3 from TMSCF 3 , followed by a subsequent spontaneous transformation into CuC 2 F 5 . Various aryl iodides were pentafluoroethylated with the TMSCF 3 -derived CuC 2 F 5 . This method represents the first practical and efficient method for pentafluoroethylation of aryl iodides using commercially available TMSCF 3 as a pentafluoroethyl precursor., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A new method for the on-site preparation of tetrafluoroethylene (TFE) and a procedure for its efficient use in pentafluoroethylation by fluoride addition were developed by using a simple two-chamber system. The on-site preparation of TFE was accomplished by dimerization of difluorocarbene derived from (trifluoromethyl)trimethylsilane (TMSCF 3 ) under mild conditions. Other fluoroalkylation reactions, such as (aryloxy)tetrafluoroethylation and tetrafluoroethylation processes, were also achieved using a similar approach. This work not only demonstrates a convenient and safe approach for the generation and use of TFE in academic laboratories, but also provides a new strategy for pentafluoroethylation., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A general method for the efficient difluoromethylation of alcohols using commercially available TMSCF 2 Br (TMS=trimethylsilyl) as a unique and practical difluorocarbene source is developed. This method allows primary, secondary, and even tertiary alkyl difluoromethyl ethers to be synthesized under weakly basic or acidic conditions. The reaction mainly proceeds through the direct interaction between a neutral alcohol and difluorocarbene, which is different from the difluoromethylation of phenols. Moreover, alcohols containing other moieties that are also reactive toward difluorocarbene can be transformed divergently by using TMSCF 2 Br. This research not only solves the synthetic problem of difluorocarbene-mediated difluoromethylation of alcohols, it also provides new insights into the different reaction mechanisms of alcohol difluoromethylation and phenol difluoromethylation with difluorocarbene species., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Aromatic cation activation is a useful strategy to promote deoxyfunctionalization; however, the deoxyfluorination of alcohols with cyclopropenium cation remains an unsolved problem due to the weak nucleophilicity of fluoride ion. Here we report the use of 3,3-difluoro-1,2-diarylcyclopropenes (CpFluors) as easily accessible and reactivity-tunable deoxyfluorination reagents. The electronic nature of CpFluors is critical for fluorination of monoalcohols via alkoxycyclopropenium cations, and CpFluors with electron-rich aryl substituents facilitate the transformation with high efficiency; however, selective monofluorination of 1,2- and 1,3-diols, which proceeds via cyclopropenone acetals, is less dependent on the electronic nature of CpFluors. Moreover, CpFluors are more sensitive to the electronic nature of alcohols than many other deoxyfluorination reagents, thus fluorination of longer diols can be achieved selectively at the relatively electron-rich position. This research not only unveils the first example of deoxyfluorination reagents that contain an all-carbon scaffold, but also sheds light on the divergent reactivity of cyclopropenium cation in deoxyfunctionalization of alcohols., Competing Interests: J.H. and F.W. have a patent on the synthetic application of CpFluors described in the manuscript: Method for preparing organic fluorides. Chinese Patent, CN 102285849A (2011).

A new olefination protocol for transition-metal-free cross-coupling of two carbene fragments arising from two different sources, namely, a nonfluorinated carbene fragment resulting from a diazo compound and a difluorocarbene fragment derived from Ruppert-Prakash reagent (TMSCF3) or TMSCF2Br, has been developed. This gem-difluoroolefination proceeds through the direct nucleophilic addition of diazo compounds to difluorocarbene followed by elimination of N2. Compared to previously reported Cu-catalyzed gem-difluoroolefination of diazo compounds with TMSCF3, which possesses a narrow substrate scope due to a demanding requirement on the reactivity of diazo compounds and in-situ-generated CuCF3, this transition-metal-free protocol affords a general and efficient approach to various disubstituted 1,1-difluoroalkenes, including difluoroacrylates, diaryldifluoroolefins, as well as arylalkyldifluoroolefins. In view of the ready availability of diazo compounds and difluorocarbene reagents and versatile transformations of 1,1-difluoroalkenes, this new gem-difluoroolefination method is expected to find wide applications in organic synthesis.

The first palladium-catalyzed direct monofluoromethylation of arylboronic esters to produce monofluoromethyl arenes is reported. The reaction is typically carried out at room temperature within 4 h and has a good functional group tolerance. The monofluoromethylating agent, CH2FI, was readily prepared via a halogen-exchange process.

Background: 1,1-Difluoroalkenes cannot only be used as valuable precursors for organic synthesis, but also act as bioisosteres for enzyme inhibitors. Among various methods for their preparation, the carbonyl olefination with difluoromethylene phosphonium ylide represents one of the most straightforward methods., Results: The combination of (chlorodifluoromethyl)trimethylsilane (TMSCF2Cl) and triphenylphosphine (PPh3) can be used for the synthesis of gem-difluoroolefins from carbonyl compounds. Comparative experiments demonstrate that TMSCF2Cl is superior to (bromodifluoromethyl)trimethylsilane (TMSCF2Br) and (trifluoromethyl)trimethylsilane (TMSCF3) in this reaction., Conclusion: Similar to many other Wittig-type gem-difluoroolefination reactions in the presence of PPh3, the reaction of TMSCF2Cl with aldehydes and activated ketones is effective.

A novel Cu-catalyzed gem-difluoroolefination of diazo compounds is described. This transformation starts from readily available TMSCF3 and diazo compounds, via trifluoromethylation followed by C-F bond cleavage, to afford the desired 1,1-difluoroalkene products.

Two-in-one: Me3 SiCF2 Br is an efficient difluorocarbene source and is compatible with both neutral and aqueous basic conditions. Bromide-ion-initiated [2+1] cycloaddition with alkenes/alkynes and hydroxide ion promoted α-addition with (thio)phenols, (thio)alcohols, sulfinates, heterocyclic amines, and H-phosphine oxides give the corresponding gem-difluorinated compounds with broad functional-group tolerance., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)