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Described is a one-pot vicinal fluorination-iodination of arynes at room temperature. The diphenyliodonium salt proved to be a privileged catalyst for this nucleophilic fluorination process using CsF as a fluorine source, and a subsequent facile electrophilic iodination with C4 F9 I was also found to be crucial to ensure the efficient fluorination. This new synthetic protocol has a broad substrate scope under mild reaction conditions., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Experimental evidence for hypervalent compounds of second‐row elements is still scarce in literature. Here, we present the first report of the long‐sought binary, hypervalent trifluorooxygenate anion [OF3]−. It was isolated in solid Ne matrices under cryogenic conditions after reacting oxygen difluoride with free fluoride ions from laser ablation of alkali metal fluorides MF (M=Li−Cs). VSEPR theory and calculations at the CCSD(T) level predict a C2v‐symmetric T‐shape structure with one short and two long O−F bond lengths in [OF3]−. This is confirmed experimentally by FTIR spectroscopy in combination with isotopic labeling. Analysis of the natural local molecular orbitals shows the presence of one 2c–2e and one 3c–4e bond each. Natural resonance theory indicates the importance of the stability of [OF2]⋅− for the stability of [OF3]−. Although free [OF2]⋅− was not detected, the species MOF2 (M=Na−Cs) could be observed in the same experiments, which are best described as contact ion pairs of M+[OF2]⋅−. [ABSTRACT FROM AUTHOR]

The 2,2‐difluoroethyl group is an important lipophilic hydrogen bond donor in medicinal chemistry, but its incorporation into small molecules is often challenging. Herein, we demonstrate electrophilic 2,2‐difluoroethylation of thiol, amine and alcohol nucleophiles with a hypervalent iodine reagent, (2,2‐difluoro‐ethyl)(aryl)iodonium triflate, via a proposed ligand coupling mechanism. This transformation offers a complementary strategy to existing 2,2‐difluoroethylation methods and allows access to a wide range of 2,2‐difluoroethylated nucleophiles, including the drugs Captopril, Normorphine and Mefloquine. [ABSTRACT FROM AUTHOR]

Hypervalent iodine compounds are described with perfluoroalkyl chains and S‐perfluoromethyl sulfoximines as ligands of the halogen. The influence of these groups on the stability of the cyclic structure is studied. The crucial role of the trifluoromethyl chain is clearly highlighted as an efficient ligand for the hypervalency. The structure and the reactivity of the new skeletons are discussed in detail. [ABSTRACT FROM AUTHOR]

A regioselective fluorocyclisation of β,γ‐unsaturated oximes through I(I)/I(III) catalysis is disclosed to generate 5‐fluoromethylated isoxazolines. The transformation leverages p‐iodotoluene as an inexpensive catalyst, Selectfluor® as the terminal oxidant and an amine⋅HF complex (1 : 7.5) as both the fluoride and Brønsted acid source. The λ3‐iodane p‐TolIF2, which is generated in situ, engages the pendant alkene of the substrate to facilitate a cyclisation/fluorination sequence. A range of 5‐fluoromethyl isoxazolines can be generated using this method, including aliphatic and aromatic systems (up to 56 % yield). Single crystal X‐ray analysis of a representative example reveals a conformation that is consistent with the stereoelectronic gauche effect between the exocyclic C(sp3)−F bond and the C(sp3)−O of the isoxazoline (ϕOCCF=−62.0°). [ABSTRACT FROM AUTHOR]

Phosphoranides are interesting hypervalent species which serve as model compounds for intermediates or transition states in nucleophilic substitution reactions at trivalent phosphorus substrates. Herein, the syntheses and properties of stable trifluoromethylphosphoranide salts are reported. [K(18‐crown‐6)][P(CF3)4], [K(18‐crown‐6)][P(CF3)3F], and [NMe4][P(CF3)2F2] were obtained by treatment of trivalent precursors with sources of CF3− or F− units. These [P(CF3)4‐nFn]− (n=0–2) salts exhibit fluorinating (n=1–2) or trifluoromethylating (n=0) properties, which is disclosed by studying their reactivity towards selected electrophiles. The solid‐state structures of [K(18‐crown‐6)][P(CF3)4] and [K(18‐crown‐6)][P(CF3)3F] are ascertained by single crystal X‐ray crystallography. The dynamics of these compounds are investigated by variable temperature NMR spectroscopy. [ABSTRACT FROM AUTHOR]

Organofluorine compounds are widely used in pharmaceutical, agrochemical, and materials sciences. The syntheses and applications of fluorinated organoborons facilitate the rapid and modular assemblies of fluorine‐containing molecules because of the versatility of C−B bonds in diverse chemical transformations. Reported herein is a migratory geminal difluorination of aryl‐substituted alkenyl N‐methyliminodiacetyl (MIDA) boronates using commercially available Py⋅HF as the fluorine source and hyperiodine as the oxidant. The protocol offers facile access to α‐ and β‐difluorinated alkylboron compounds, both of which have previously been challenging to prepare. Mild reaction conditions, broad substrate scope, good functional‐group tolerance, and moderate to good yields were observed. The utility of these products is demonstrated by further transformations of the C−B bond into other valuable functional groups. On the move: A migratory geminal difluorination of aryl‐substituted alkenyl N‐methyliminodiacetyl (MIDA) boronates using commercially available Py⋅HF as the fluorine source is reported. The protocol offers an unprecedented opportunity for the synthesis of α‐ and β‐difluorinated alkylboron compounds. Mild reaction conditions, broad substrate scope, good functional‐group tolerance, and moderate to good yields were observed. [ABSTRACT FROM AUTHOR]

The treatment of phenyl‐protected pentafluoroethylstannanes, Sn(C2F5)4–nPhn (n = 1–3), with anhydrous HF results in the formation of the corresponding fluorostannanes which are associated in the solid state but form monomeric and dimeric fluoride complexes in solution. Due to the pronounced Lewis acidity caused by the electron‐withdrawing pentafluoroethyl groups, these stannanes represent suitable precursors for the synthesis of neutral, monoanionic and dianionic hexacoordinate tin(IV) complexes. The employment of an excess of cesium fluoride and 1,10‐phenanthroline exclusively leads to the octahedral complexes [Sn(C2F5)nF6–n]2– (n = 2–4) and [Sn(C2F5)nF4–n(phen)] (n = 1–3). The addition of bases, donating solvents as well as LiF, on the other hand, selectively affords salts containing dinuclear anions of the form [(C2F5)3Sn(µ‐F)3Sn(C2F5)3]– and [(C2F5)2F2Sn(µ‐F)2SnF2(C2F5)2]2–. [ABSTRACT FROM AUTHOR]

We report a denitrogenative dihalogenation reaction of phenyldiazomethanes in which the hypervalent iodine reagents PhICl2 and TolIF2 act as surrogates for elemental chlorine and fluorine. Halogen transfer from iodane to aryldiazomethane is described, as is a tandem oxidative dihalogenation reaction between iodane and hydrazone. This is the first use of non-α-stabilized diazo compounds in this reaction, which provided an efficient synthesis of aryldifluoromethane (ArCHF2) and aryldichloromethane (ArCHCl2) derivatives. [ABSTRACT FROM AUTHOR]

A combined experimental and computational investigation was conducted to identify a mild and effective Lewis-acidic activator for TolIF2 in the gem-difluorination of diazo compounds. Computationally, borosilicate, a common constituent of laboratory glassware, was found to spontaneously activate TolIF2, and an extensive experimental survey confirmed borosilicate as the most effective activator to date. The key to realizing this borosilicate-activated reaction was the use of high purity TolIF2, which is prepared by a reproducible, multigram-scale synthesis. [ABSTRACT FROM AUTHOR]

Novel methodology for O-functionalization of carbohydrate derivatives has been established using bench-stable and easily prepared iodonium(III) reagents. Both electron-withdrawing and electron-donating aryl groups were introduced under ambient conditions and without precautions to exclude air or moisture. Furthermore, the approach was extended both to full arylation of cyclodextrin, and to trifluoroethylation of carbohydrate derivatives. This is the first general approach to introduce traditionally non-electrophilic groups into any of the OH groups around the sugar backbone. The methodology will be useful both in synthetic organic chemistry and biochemistry, as important functional groups can be incorporated under simple and robust reaction conditions in a fast and efficient manner. [ABSTRACT FROM AUTHOR]

A new reaction for the rhodium-catalyzed geminaldifunctionalization- based fluorination is presented. The substrates are aromatic and aliphatic diazocarbonyl compounds. As the fluorine source a stable and easily accessible benziodoxole reagent was used. A variety of alcohol, phenol, and carboxylic acid reagents were employed to introduce the second functionality. The reaction was extended to trifluoromethylation using a benziodoxolon reagent. The fluorination and trifluoromethylation reactions probably proceed by a rhodium- containing onium ylide type intermediate, which is trapped by either the F or CF3 electrophiles. [ABSTRACT FROM AUTHOR]

A new reaction for the rhodium-catalyzed geminaldifunctionalization- based fluorination is presented. The substrates are aromatic and aliphatic diazocarbonyl compounds. As the fluorine source a stable and easily accessible benziodoxole reagent was used. A variety of alcohol, phenol, and carboxylic acid reagents were employed to introduce the second functionality. The reaction was extended to trifluoromethylation using a benziodoxolon reagent. The fluorination and trifluoromethylation reactions probably proceed by a rhodium- containing onium ylide type intermediate, which is trapped by either the F or CF3 electrophiles. [ABSTRACT FROM AUTHOR]

A series of new hypervalent iodine reagents based on the 1,3-dihydro-3,3-dimethyl-1,2-benziodoxole and 1,2-benziodoxol-3-(1H)-one scaffolds, which contain a functionalized tetrafluoroethyl group, have been prepared, characterized, and used in synthetic applications. Their corresponding electrophilic fluoroalkylation reactions with various sulfur, oxygen, phosphorus, and carbon-centered nucleophiles afford products that feature a tetrafluoroethylene unit, which connects two functional moieties. A related λ3-iodane that contains a fluorophore was shown to react with a cysteine derivative under mild conditions to give a thiol-tagged product that is stable in the presence of excess thiol. Therefore, these new reagents show a significant potential for applications in chemical biology as tools for fast, irreversible, and selective thiol bioconjugation. [ABSTRACT FROM AUTHOR]

A new class of fluorinated lactones was prepared by the intramolecular fluorocyclizations of unsaturated carboxylic acids by using the stable fluoroiodane reagent in combination with AgBF4. This unique reaction incorporates a cyclization, an aryl migration, and a fluorination all in one step. The fluoroiodane reagent, prepared easily from fluoride, can also be used without a metal catalyst to give moderate yields within just 1 hour, thus demonstrating that it is a suitable reagent for developing new 18F-labelled radiotracers for PET imaging. [ABSTRACT FROM AUTHOR]

The copper-catalyzed C( sp2)H trifluoromethylation of N,N-disubstituted hydrazones using the Togni reagent is demonstrated to proceed efficiently for aliphatic aldehyde-derived substrates. The success of the reactions relied on the choice of the N,N-diphenylamino group as the terminal hydrazone amino group where N,N-dialkylamino groups were preferred for (hetero)aromatic aldehyde-derived substrates. In addition, the trifluoromethylated N-arylhydrazones are shown to be ideal substrates for Fischer indole synthesis allowing a straightforward, three-step access to 2-trifluoromethylindole derivatives from simple aldehydes. [ABSTRACT FROM AUTHOR]

Described is a one-pot vicinal fluorination-iodination of arynes at room temperature. The diphenyliodonium salt proved to be a privileged catalyst for this nucleophilic fluorination process using CsF as a fluorine source, and a subsequent facile electrophilic iodination with C4F9I was also found to be crucial to ensure the efficient fluorination. This new synthetic protocol has a broad substrate scope under mild reaction conditions. [ABSTRACT FROM AUTHOR]

Thermal reaction between XeF2 and excess TiF4 resulted in the unexpected formation of a highly ionized XeII species. The products [Xe2F3][Ti8F33] and [XeF]2[Ti9F38] represent the first examples of [Xe2F3]+ and [XeF]+ compounds, which differ from known XeII salts containing discrete fluoride anions with pentavalent metalloid/metal centers. A new structural type of 2D polyanion [Ti8F33]− and the formation and structure of the novel 1D [Ti9F38]2− are discussed. Both products were characterized by single-crystal X-ray analysis and Raman spectroscopy. [ABSTRACT FROM AUTHOR]

An air- and moisture-stable fluoroiodane in the presence of AgBF4 is suitable for selective geminal difluorination of styrenes under mild reaction conditions. One of the CF bonds is formed by transfer of electrophilic fluorine from the hypervalent iodine reagent, while the other one arises from the tetrafluoroborate counterion of silver. Deuterium-isotope-labelling experiments and rearrangement of methyl styrene substrates suggest that the reaction proceeds through a phenonium ion intermediate. [ABSTRACT FROM AUTHOR]

Because of its high lipophilicity, the CF3S group has always interested chemists. However, strategies to introduce it into organic molecules have been, for the most part, reserved to specialized 'fluorine chemists'. Recent published work has demystified these preconceived ideas by proposing new efficient methods or easy-to-handle reagents to enrich the toolbox of chemists. However, all these new concepts arise from the pioneering works of the past! In this review, we will do a 'back to the future' by remembering the most significant results of the past and by presenting extensions and novelties of the present and for the future. [ABSTRACT FROM AUTHOR]

Biologically attractive trifluoromethyl-2-isoxazoline N-oxides were synthesized in good yields for the first time by the [hydroxy(tosyloxy)iodo]benzene-mediated oxidative N-O coupling of β-trifluoromethyl β-hydroxy ketoximes generated from trifluoromethyl β-keto alcohols. The present method allows the synthesis of previously unknown 5-trifluoromethyl-2-isoxazoline N-oxides and also provides an alternative for the enantioselective synthesis of antiparasitic 5-trifluoromethyl-2-isoxazolines by sequential reduction. [ABSTRACT FROM AUTHOR]

Replacement of the iodine atom in an iodine (III) CF3‐transfer reagent with a Te‐aryl moiety was accomplished in a three‐step synthetic sequence. Three compounds of this type have been prepared, two of which were characterized by X‐ray diffraction. Single crystal structures were also obtained for three related Te(IV) compounds unreported so far (4a, 4b, 6b). Comparison with the iodine (III) analogues indicate a large degree of structural similarity, however these species display an interesting decomposition pathway under thermal conditions. In addition to the expected Te−CF3 bond cleavage, C−F bond cleavage is also observed, unlike in the case of iodine (III) compounds. [ABSTRACT FROM AUTHOR]