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A AgF-mediated fluorination with a concomitant cross-coupling between a gem-difluoroolefin and a non-fluorinated olefin is reported. This highly efficient method provides facile access to both α-CF3 alkenes and β-CF3 ketones, which otherwise remain challenging to be directly prepared. The application of this method is further demonstrated by the synthesis of bioactive isoxazoline derivatives. This approach represents a conceptually novel route to trifluoromethylated compounds that combines the in situ generation of the CF3 moiety and a C-H functionalization in a single reaction system., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The direct conversion of diaryl ketones and enolizable aliphatic aldehydes into gem-difluoroalkenes has been a long-standing challenge in organofluorine chemistry. Herein, we report efficient strategies to tackle this problem by using difluoromethyl 2-pyridyl sulfone as a general gem-difluoroolefination reagent. The gem-difluoroolefination of diaryl ketones proceeds by acid-promoted Smiles rearrangement of the carbinol intermediate; the gem-difluoroolefination is otherwise difficult to achieve through a conventional Julia-Kocienski olefination protocol under basic conditions due to the retro-aldol type decomposition of the key intermediate. Efficient gem-difluoroolefination of aliphatic aldehydes was achieved by the use of an amide base generated in situ (from CsF and tris(trimethylsilyl)amine), which diminishes the undesired enolization of aliphatic aldehydes and provides a powerful synthetic method for chemoselective gem-difluoroolefination of multi-carbonyl compounds. Our results provide new insights into the mechanistic understanding of the classical Julia-Kocienski reaction., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Although many methods are available for the synthesis of optically enriched monofluoromethyl secondary alcohols, synthesizing optically enriched monofluoromethyl tertiary alcohols remains a challenge. An efficient and easy-to-handle nucleophilic fluoromethylation protocol was developed. The current monofluoromethylation showed much higher facial selectivity than the corresponding difluoromethylation and proceeded via a different type of transition state. Excellent stereoselective control at the fluorinated carbon chiral center was found, an effect believed to be facilitated by the dynamic kinetic resolution of the chiral α-fluoro carbanions., (Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A stereoselective synthesis of enantiomerically enriched difluoromethyl tertiary alcohols by tuning the reactivity of difluoromethyl sulfoximines from electrophilic to nucleophilic difluoromethylating agents is reported. The key feature of this chemistry is the diastereoselective addition of the difluoromethyl sulfoximine to the prochiral carbon of the ketone. The present method was used to prepare enantiomerically enriched difluoromethyl secondary alcohols and difluorinated analogues of the natural products gossonorol and boivinian B, demonstrating the potency of the method.

Iodo- and bromodifluoromethylated compounds are important synthetic intermediates and halogen-bond acceptors. However, direct introduction of -CF(2)I and -CF(2)Br groups through nucleophilic addition is particularly challenging because of the high tendency of decomposition of CF(2)Br(-) and CF(2)I(-) to difluorocarbene. In this work, we have developed a formal nucleophilic iodo- and bromodifluoromethylation for carbonyl compounds. The key strategy of the method is the halogenation of in situ-generated sulfinate intermediates from the Julia-Kocienski reaction to change the reaction pathway from the traditional olefination to alkylation. Interesting halogen-π interactions between the halocarbon and aromatic donors were observed in the crystal structures of the products. The method could also be extended to the introduction of other fluorinated groups, such as -CFClBr, -CFClI, -CFBr(2), and -CFMeI, which opens up new avenues for the synthesis of a wide range of useful fluorinated products.

Alkoxide-induced nucleophilic pentafluoroethylation and trifluoromethylation of aldehydes, ketones, and imines using pentafluoroethyl phenyl sulfone (PhSO(2)CF(2)CF(3), 1) and trifluoromethyl phenyl sulfone (PhSO(2)CF(3), 2), respectively, have been successfully achieved. High diastereoselectivity was observed during the perfluoroalkylation of homochiral sulfinimines to give the corresponding perfluoroalkyl sulfinamides.

Difluoromethyl 2-pyridyl sulfone, a previously unknown compound, was found to act as a novel and efficient gem-difluoroolefination reagent for both aldehydes and ketones. It was found that the fluorinated sulfinate intermediate in the reaction is relatively stable, which can be observed by (19)F NMR and trapped with CH(3)I.

We have developed a new strategy for controllable single and double difluoromethylene (CF2) formal insertions into C−H bonds of aldehydes with nearly full selectivity under transition‐metal‐free conditions. The key to the success of controllable CF2 insertions lies in the well‐defined formation of 2,2‐difluoroenolsilyl ether and 2,2,3,3‐tetrafluorocyclopropanolsilyl ether intermediates using difluorocarbene reagent TMSCF2Br (TMS=trimethylsilyl). These two intermediates can react with various electrophiles including proton sources and various halogenation reagents, allowing for the access to diverse arrays of ketones containing difluoromethylene (CF2) and tetrafluoroethylene (CF2CF2) units. The first synthesis of relatively stable 2,2,3,3‐tetrafluorocyclopropanolsilyl ethers has been achieved, which offers a new platform to explore other unknown chemical space. [ABSTRACT FROM AUTHOR]

The transition‐metal‐catalyzed carbonylation reaction is a useful approach for ketone synthesis. However, it is often problematic to use exogenous carbonyl reagents, such as gaseous carbon monoxide. In this manuscript, we report a novel palladium‐catalyzed coupling reaction of gem‐difluoroalkenes and aryl boronic acids that yields bioactive indane‐type ketones with an all‐carbon α‐quaternary center. Characterization and stoichiometric reactions of the key intermediates RCF2PdII support a water‐induced defluorination and cross‐coupling cascade mechanism. The vinyl difluoromethylene motif serves as an in situ carbonyl precursor which is unprecedented in transition‐metal‐catalyzed coupling reactions. It is expected to raise broad research interest from the perspectives of ketone synthesis, fluoroalkene functionalization, and rational design of new synthetic protocols based on the unique reactivity of difluoroalkyl palladium(II) species. [ABSTRACT FROM AUTHOR]

Aryl fluorosulfonates are developed as a deoxyfluorinating reagent in the transformation of primary and secondary alcohols into the corresponding alkyl fluorides. These reagents feature easy availability, low-cost, high stability and high efficiency. Diverse functionalities including aldehyde, ketone, ester, halogen, nitro, alkene, and alkyne are well tolerated under mild reaction conditions. [ABSTRACT FROM AUTHOR]

A pentacoordinate bis(difluoromethyl)silicate anion, [Me3Si(CF2H)2]−, is observed for the first time by the activation of Me3SiCF2H with a nucleophilic alkali-metal salt and 18-crown-6. Further study on its reactivity by tuning the countercation effect led to the discovery and development of an efficient, catalytic nucleophilic difluoromethylation of enolizable ketones with Me3SiCF2H by using a combination of CsF and 18-crown-6 as the initiation system. Mechanistic investigations demonstrate that [(18-crown-6)Cs]+[Me3Si(CF2H)2]− is a key intermediate in this catalytic reaction. [ABSTRACT FROM AUTHOR]

Fluorinated ketones are intriguing compounds in synthetic chemistry and life science-related fields. The development of efficient methodologies to obtain these compounds is of significant importance and has therefore attracted considerable attention. This Minireview highlights recent progress made in the synthesis of fluorine-containing ketones, with an emphasis on those methods in which the construction of carbonyl groups is synergetic with distal (β -, γ -, δ -, etc.) incorporation of fluorine atoms or fluorinated groups. [ABSTRACT FROM AUTHOR]

A AgF-mediated fluorination with a concomitant cross-coupling between a gem-difluoroolefin and a non-fluorinated olefin is reported. This highly efficient method provides facile access to both α-CF3 alkenes and β-CF3 ketones, which otherwise remain challenging to be directly prepared. The application of this method is further demonstrated by the synthesis of bioactive isoxazoline derivatives. This approach represents a conceptually novel route to trifluoromethylated compounds that combines the in situ generation of the CF3 moiety and a CH functionalization in a single reaction system. [ABSTRACT FROM AUTHOR]

Abstract: A new nucleophilic difluoromethylation chemistry using fluoride-induced (phenylsulfonyl)difluoromethylation with TMSCF2SO2Ph followed by the magnesium-metal-mediated desulfonylation has been achieved. This methodology is compatible with both enolizable and non-enolizable aldehydes and ketones and has special advantage in the case of enolizable aldehydes. The new efficient desulfonylation method is considered to be environmentally benign due to the absence of mercury. [Copyright &y& Elsevier]

Abstract: A fluoride-induced nucleophilic (phenylthio)difluoromethylation method using TMS–CF2SPh has been achieved. This new methodology efficiently transfers “PhSCF2” group into both enolizable and non-enolizable aldehydes and ketones to give corresponding (phenylthio)difluoromethylated alcohols in good to excellent yields. Diphenyldisulfide can also be (phenylthio)difluoromethylated into PhSCF2SPh in high yield. The reaction with methyl benzoate, however, gives only low yield of (phenylthio)difluoromethyl phenyl ketone. The above-obtained PhSCF2-containing alcohols can be further transformed into difluoromethyl alcohols using an oxidation–desulfonylation procedure. This new type of nucleophilic (phenylthio)difluoromethylation methodology may have other potential applications in the medicinal and agrochemical fields. [Copyright &y& Elsevier]

Heteroaryl sulfones are capable of converting the carbonyl functionalities to alkenyl motifs, which is well-known as Julia–Kocienski olefination reaction. However, their sulfoxide analogues have failed in such an olefination reaction for over twenty years. In this Letter, we demonstrate that the heteroaryl sulfoxide-participated carbonyl olefination reaction can be realized under certain conditions. Furthermore, a novel defluorinative olefination of diaryl ketones has been achieved with 2-pyridyl sulfoxides. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this study is to exploit the one-dimension structure and good proton conduction of phosphorylated silica nanotubes for high proton conductivity of proton exchange membrane (PEM). Three types of poly(vinylphosphonic acid-co-divinylbenzene)/silica nanotubes with different aspect ratios are synthesized and incorporated into the sulfonated poly(ether ether ketone) (SPEEK) matrix to prepare composite membranes. The poly(vinylphosphonic acid) segments in the nanotubes could construct facile proton-conduction pathway along this one-dimensional nanostructure. The nanotubes with high aspect ratio exhibit more pronounced effect in elevating the proton conductivity of membranes, revealing the importance of continuity of conduction pathway on proton transport. The membrane incorporated with the nanotubes of the largest aspect ratio of 45.9 exhibits the highest proton conductivity of 0.1032 S cm−1 at 30 °C, 100% RH, which was 84% higher than that of SPEEK control membrane. Moreover, the nanotubes can reduce the methanol permeability, and improve mechanical stability of the membranes. [Copyright &y& Elsevier]

Abstract: A series of sulfur-, selenium- and tellurium-containing (phenylchalcogen)difluoromethylation reagents PhSCF2H (1a), PhSeCF2H (1b), and PhTeCF2H (1c) were prepared, and their relative reactivity towards aldehydes, ketones, and imines was investigated. Compared to the former developed (phenylchalcogen)difluoromethylation reagents, these reagents are relatively easily available and more atom-economical in fluoroalkylation reactions. It was found that the efficient nucleophilic (phenylchalcogen)difluoromethylation of aldehydes, ketones, and imines could be achieved with 1a–1c. Reagents 1a and 1b showed better reactivity than 1c toward carbonyl compounds and imines, and PhOCF2H (1d) was found to be unable to undergo similar fluoroalkylation reactions. [Copyright &y& Elsevier]

Abstract: We have investigated the different chlorodifluoromethyl aryl ketones 1a–1g and sulfones 2a–2h as difluorocarbene reagents for O- and N-difluoromethylations. It was found that the sulfone reagents 2 were generally more efficient in difluoromethylation than the ketone reagents 1. Furthermore, while the different substituents on ketone reagents 1 did not show a remarkable impact on the difluoromethylation reaction, the substituent effect on the sulfone reagents 2 was much more significant. Finally, we found that p-chlorophenyl chlorodifluoromethyl sulfone 2d and p-nitrophenyl chlorodifluoromethyl sulfone 2h were among the most powerful difluorocarbene reagents in this category for O-difluoromethylations. [Copyright &y& Elsevier]

Abstract: We have successfully achieved nucleophilic (phenylsulfinyl)difluoromethylation of both enolizable and non-enolizable aldehydes and ketones by using difluoromethyl phenyl sulfone (1) as the fluoroalkylating agent. Although the chemical yields of the reactions are good to excellent, the observed diastereoselectivity is poor (dr=1:1.04–2.03). The present synthetic methodology provides a convenient alternative for the preparation of α-(phenylsulfinyl)difluoromethylated carbinols that were previously synthesized via a two-step procedure. [Copyright &y& Elsevier]

Hitherto unknown Julia-Kocienski type olefination reactions of 2-pyridyl sulfoxides and 1,3-benzothiazol-2-yl sulfoxides are described. [ABSTRACT FROM AUTHOR]

The reaction differs from the previously known decarboxylative trifluoromethylation protocols as water is involved as a reagent in the reaction. [ABSTRACT FROM AUTHOR]