This is the third in the series of Thematic Issues on organo-fluorine chemistry for this journal. Fluorine touches all categories of performance compounds extending from bioactives to organic materials, and society demands continual improvements in the quality and performance of products and devices. This requires innovation in molecular design, and because of its particular ability to tune properties, fluorine chemistry may provide the means. To meet these demands we continually need new methods and new building blocks to prepare new classes of compounds. As our ability to prepare and apply organo-fluorine molecules improves, it demands a deeper understanding of their properties and behaviour. The papers of the Thematic Series touch on all of these aspects and the area remains as innovative and relevant as ever.
See also the Thematic Series:
Organo-fluorine chemistry II
Organo-fluorine chemistry
Graphical Abstract
Scheme 1: Strategy towards the target molecules.
Scheme 2: Synthesis of enones with a gem-difluoroalkyl side chain.
Scheme 3: Synthesis of pyrazolines with a gem-difluoro side chain.
Scheme 4: One-pot synthesis of pyrazolines with a gem-difluoro side chain.
Scheme 5: Synthesis of pyrrolines with a gem-difluoro alkyl side chain.
Scheme 6: One-pot synthesis of pyrrolines with a gem-difluoro side chain.
Scheme 7: Pd-catalyzed coupling reactions towards chemical libraries of pyrazolines with a gem-difluoro side ...
Scheme 8: Pd-catalyzed coupling reactions towards chemical libraries of pyrrolines with a gem-difluoro side c...
Graphical Abstract
Scheme 1: Synthesis of optically active N-acyloxazolidinone 5 from 4,4,4-trifluorobutanoic acid. Conditions: ...
Scheme 2: Synthesis of enantiomerically pure (2S,3S)-5-F3Ile and (2R,3S)-5-F3-allo-Ile. TMGA = 1,1,3,3-tetram...
Figure 1: Retention times of Fmoc amino acids plotted against the van der Waals volume of their side chains. ...
Figure 2: CD spectra of K-5-F3Ile and K-Ile peptides (KX: Ac-YGGKAAAAKAXAAKAAAAK-NH2). The K-4’-F3Ile spectru...
Graphical Abstract
Scheme 1: Proposed reaction mechanism between 1 and MeLi.
Scheme 2: Furan synthesis from a mixture of 5a and 6a.
Scheme 3: Deuteration of anionic species from 4.
Figure 1: A part of 1H NMR chart of 4 and its deuterated mixture.
Scheme 4: Lithiation of 4 and the following electrophilic reactions.
Scheme 5: Alternative reaction mechanism between 1 and MeLi.
Graphical Abstract
Scheme 1: Trifluoromethylation of α,β-unsaturated ketones.
Scheme 2: Proposed mechanism for the conjugate trifluoromethylation of α,β-unsaturated ketones by S-(trifluor...
Graphical Abstract
Figure 1: Transamination of 1a with amines. (Isolated yields, in parentheses crude yields determined by 19F N...
Figure 2: Reaction of 1a with bis-nucleophiles. (Isolated yields, in parentheses crude yields determined by 19...
Figure 3: Synthesis of fluoroalkylthio analogs of imipramine. (Isolated yields, in parentheses crude yields d...
Graphical Abstract
Figure 1: Schematic view of the different types of molecular arrangements in acene-based molecular semiconduc...
Figure 2: Target compound 1 and its calculated electrostatic potential surface. The colors denote a range of ...
Scheme 1: Syntheses of the substitution products 1 and 3: a) Catechol, K2CO3, THF; 60 °C, 4 h (12%). b) Catec...
Figure 3: The crystal structure of 1 is characterized by brick wall-like stacks (left), which are arranged in...
Figure 4: The electrostatic factors determining the packing of 1. The laterally interlinked sheets are stabil...
Figure 5: The four closest pairs A–D in the crystal structure of 1. The corresponding transfer integrals for ...
Figure 6: Geometries of HOMO (−5.64 eV, left) and LUMO (−1.29 eV, right) of 1 [15].
Graphical Abstract
Figure 1: Example of bioactive molecules bearing the 2-isoxazoline nucleus.
Scheme 1: Synthesis of 3-trifluoromethyl-2-isoxazolines.
Scheme 2: Synthesis of aldoxime 2.
Figure 2: Dimerization and isomerization products from nitrile oxides.
Figure 3: Dimerization of 4 yielding bis(trifluoromethyl)furoxan 6.
Figure 4: Depiction of the geometry (left column) and isodensity surface of the reacting frontier molecular o...
Figure 5: FMO energy levels of dipole 4 and dipolarophiles 5a and 5k calculated at the B3LYP/6-31G* level. Co...
Figure 6: Yields of the cycloaddition reaction plotted against the HOMO energy levels of the dipolarophile pa...
Graphical Abstract
Figure 1: Copper-catalyzed trifluoromethylation of various aryl iodides. Yields were determined by 19F NMR an...
Scheme 1: Observation of CuCF3 species in 19F NMR spectrum. aEquivalents based on Zn(CF3)I. bYields based on ...
Scheme 2: Proposed mechanism of copper-catalyzed trifluoromethylation.
Graphical Abstract
Scheme 1: Experiments to elucidate the reaction mechanism.
Scheme 2: The proposed reaction mechanism.
Graphical Abstract
Figure 1: SN2 reaction of activated alkyl fluorides and calculated transition state for the reaction of morph...
Figure 2: Proposed activation of C–F bonds mediated by a triol.
Graphical Abstract
Scheme 1: Preparation of 2,2-difluoro-1-iodoethenyl tosylate (2).
Graphical Abstract
Scheme 1: Pd-catalyzed monofluoromethylation of pinacol phenylboronate [44].
Scheme 2: Cu-catalyzed monofluoromethylation with 2-PySO2CHFCOR followed by desulfonylation [49].
Scheme 3: Cu-catalyzed difluoromethylation with α-silyldifluoroacetates [57].
Figure 1: Mechanism of the Cu-catalyzed C–CHF2 bond formation of α,β-unsaturated carboxylic acids through dec...
Scheme 4: Fe-catalyzed decarboxylative difluoromethylation of cinnamic acids [62].
Scheme 5: Preliminary experiments for investigation of the mechanism of the C–H trifluoromethylation of N-ary...
Figure 2: Plausible catalytic cycle proposed by Z.-J. Shi et al. for the trifluoromethylation of acetanilides ...
Figure 3: Plausible catalytic cycle proposed by M. S. Sanford et al. for the perfluoroalkylation of simple ar...
Figure 4: Postulated reaction pathway for the Ag/Cu-catalyzed trifluoromethylation of aryl iodides by Z. Q. W...
Figure 5: Postulated reaction mechanism for Cu-catalyzed trifluoromethylation reaction using MTFA as trifluor...
Scheme 6: Formal Heck-type trifluoromethylation of vinyl(het)arenes by M. Sodeoka et al. [83].
Figure 6: Proposed catalytic cycle for the copper-catalyzed trifluoromethylation of (het)arenes in presence o...
Figure 7: Proposed catalytic cycle for the copper-catalyzed trifluoromethylation of N,N-disubstituted (hetero...
Figure 8: Proposed catalytic cycle by Y. Zhang and J. Wang et al. for the copper-catalyzed trifluoromethylati...
Figure 9: Mechanistic rationale for the trifluoromethylation of arenes in presence of Langlois’s reagent and ...
Scheme 7: Trifluoromethylation of 4-acetylpyridine with Langlois’s reagent by P. S. Baran et al. (* Stirring ...
Scheme 8: Catalytic copper-facilitated perfluorobutylation of benzene with C4F9I and benzoyl peroxide [90].
Figure 10: F.-L. Qing et al.’s proposed mechanism for the copper-catalyzed trifluoromethylation of (hetero)are...
Figure 11: Mechanism of the Cu-catalyzed/Ru-photocatalyzed trifluoromethylation and perfluoroalkylation of ary...
Figure 12: Proposed mechanism for the Cu-catalyzed trifluoromethylation of aryl- and vinyl boronic acids with ...
Figure 13: Possible mechanism for the Cu-catalyzed decarboxylative trifluoromethylation of cinnamic acids [62].
Scheme 9: Ruthenium-catalyzed perfluoroalkylation of alkenes and (hetero)arenes with perfluoroalkylsulfonyl c...
Figure 14: N. Kamigata et al.’s proposed mechanism for the Ru-catalyzed perfluoroalkylation of alkenes and (he...
Figure 15: Proposed mechanism for the Ru-catalyzed photoredox trifluoromethylation of (hetero)arenes with trif...
Figure 16: Late-stage trifluoromethylation of pharmaceutically relevant molecules with trifluoromethanesulfony...
Figure 17: Proposed mechanism for the trifluoromethylation of alkenes with trifluoromethyl iodide under Ru-bas...
Scheme 10: Formal perfluoroakylation of terminal alkenes by Ru-catalyzed cross-metathesis with perfluoroalkyle...
Figure 18: One-pot Ir-catalyzed borylation/Cu-catalyzed trifluoromethylation of complex small molecules by Q. ...
Figure 19: Mechanistic proposal for the Ni-catalyzed perfluoroalkylation of arenes and heteroarenes with perfl...
Scheme 11: Electrochemical Ni-catalyzed perfluoroalkylation of 2-phenylpyridine (Y. H. Budnikova et al.) [71].
Scheme 12: Fe(II)-catalyzed trifluoromethylation of arenes and heteroarenes with trifluoromethyl iodide (T. Ya...
Figure 20: Mechanistic proposal by T. Yamakawa et al. for the Fe(II)-catalyzed trifluoromethylation of arenes ...
Scheme 13: Ytterbium-catalyzed perfluoroalkylation of dihydropyran with perfluoroalkyl iodide (Y. Ding et al.) ...
Figure 21: Mechanistic proposal by A. Togni et al. for the rhenium-catalyzed trifluoromethylation of arenes an...
Figure 22: Mechanism of the Cu-catalyzed oxidative trifluoromethylthiolation of arylboronic acids with TMSCF3 ...
Scheme 14: Removal of the 8-aminoquinoline auxiliary [136].
Figure 23: Mechanism of the Cu-catalyzed trifluoromethylthiolation of C–H bonds with a trifluoromethanesulfony...
Graphical Abstract
Scheme 1: Reaction of vinylamides 2a,b with 1.
Figure 1: Crystal structure of 3b with thermal ellipsoids drawn at the 30% probability level.
Scheme 2: Reaction of N-vinyllactames 2c,d with 1.
Scheme 3: Reaction of N-vinylcarbazole with 1.
Figure 2: Crystal structure of 3e with thermal ellipsoids drawn at the 30% probability level. Disordered atom...
Scheme 4: Formation of thione 5 in reaction of 4 and 1.
Figure 3: Crystal structure of 5 with thermal ellipsoids drawn at the 30% probability level.
Graphical Abstract
Scheme 1: Construction of the Cvinyl–CF3 bond.
Scheme 2: Proposed reaction paths for the trifluoromethylation of alkenes.
Figure 1: Cu(I)-catalyzed trifluoromethylation of terminal alkenes with Togni’s reagent. Isolated yield are r...
Scheme 3: Proposed mechanism for the trifluoromethylation of terminal alkenes.
Graphical Abstract
Scheme 1: Key steps from the synthesis of 6-fluoro-D-olivose (6) from D-glucose (1).
Scheme 2: De novo asymmetric syntheses of 6-deoxy-6-fluorohexoses [13].
Scheme 3: Fluorobutenoate building block 14, and related species 16 and 19 from the literature [14-16].
Scheme 4: Fluorobutenoate building blocks 25 and 26 prepared from crotonic acid.
Figure 1: Side product 27 isolated from attempted fluorination.
Figure 2: The ligand panel used in the asymmetric dihydroxylation studies. The bold oxygen shows the point of...
Scheme 5: Typical AD procedure; see Table 1 for outcomes.
Scheme 6: Conversion of enantiomerically-enriched diols to dibenzoates for HPLC analysis.
Figure 3: Diisopropyl L-tartrate (30) used as a chiral modifier for NMR determination of ee.
Figure 4: Partial 19F{1H} NMR spectra (376 MHz, L-(+)-DIPT/CDCl3, 300 K) spectra of (a) racemate 28c, (b) dio...
Figure 5: Partial 19F{1H} NMR (400 MHz, L-(+)-DIPT/CDCl3, 300 K) spectra of 28b and 28a using optimised condi...
Scheme 7: Applying cyclic sulfate methodology to gain access to anti-diastereoisomers (transformations were d...
Scheme 8: Protecting and chain extending the educts of asymmetric dihydroxylation.
Graphical Abstract
Scheme 1: Synthesis of 2-pentafluorosulfanylaldehydes by addition of SF5Cl to enol ethers.
Scheme 2: Reaction of pentafluorosulfanylaldimines with benzyloxyketene.
Scheme 3: Preparation of ethyl pentafluorosulfanylpyruvate and formation of the corresponding β-lactam.
Figure 1: The 1,2-lk stereochemistry of 7a as determined by single crystal X-ray diffraction. Thermal ellipso...
Scheme 4: Influence of the SF5 group on the initial attack of the ketene on the imine nitrogen (A) and on the...
Figure 2: The stereochemistry of 7c, 1,2-lk,lk (Si, Si-S), as determined by single crystal X-ray diffraction ...
Graphical Abstract
Figure 1: Fluorination alters the reactivity of aziridines.
Scheme 1: Fluorination makes β-lactam derivatives more reactive towards lipase-catalysed methanolysis.
Figure 2: The ring pucker in azetidine derivatives can be influenced by a C–F…N+ charge–dipole interaction.
Figure 3: Fluorination ridifies the pyrrolidine rings of ligand 10, with several consequences for its G-quadr...
Figure 4: Proline 11 readily undergoes a ring-flip process, but (4R)-fluoroproline 12 is more rigid because o...
Scheme 2: Hyperconjugation rigidifies the ring pucker of a fluorinated organocatalyst 14, leading to higher e...
Figure 5: Fluorinated piperidines prefer the axial conformation, due to stabilising C–F…N+ interactions.
Figure 6: Fluorination can rigidify a substituted azepane, but only if it acts in synergy with the other subs...
Figure 7: The eight-membered N-heterocycle 24 prefers an axial orientation of the fluorine substituent, givin...
Figure 8: Some iminosugars are “privileged structures” that serve as valuable drug leads.
Figure 9: Fluorinated iminosugar analogues 32–34 illuminate the binding interactions of the α-glycosidase inh...
Figure 10: Fluorinated miglitol analogues, and their inhibitory activity towards yeast α-glycosidase.
Figure 11: Analogues of isofagomine (31) have different pKaH values, and therefore exhibit maximal β-glucosida...
Scheme 3: General strategy for the synthesis of fluorinated N-heterocycles via deoxyfluorination.
Figure 12: Late stage deoxyfluorination in the synthesis of multifunctional N-heterocycles.
Scheme 4: During the deoxyfluorination of N-heterocycles, neighbouring group participation can sometimes lead...
Scheme 5: A building block approach for the synthesis of fluorinated aziridines 2 and 3.
Scheme 6: Building block approach for the synthesis of a difluorinated analogue of calystegine B (63).
Scheme 7: Synthesis of fluorinated analogues of brevianamide E (65) and gypsetin (68) via electrophilic fluor...
Scheme 8: Organocatalysed enantioselective fluorocyclisation.
Scheme 9: Synthesis of 3-fluoroazetidine 73 via radical fluorination.
Scheme 10: Synthesis of 3,3-difluoropyrrolidine 78 via a radical cyclisation.
Scheme 11: Chemoenzymatic synthesis of fluorinated β-lactam 4b.
Graphical Abstract
Scheme 1: Direct fluorination using microreactor systems.
Scheme 2: Use of DAST in continuous-flow reactors.
Scheme 3: Flow microreactor synthesis of fluorinated epoxides.
Scheme 4: Highly controlled isomerization of gem-difluoroalkenes.
Scheme 5: Flow system for catalytic aromatic fluorination.
Scheme 6: Continuous-flow reactor for electrophilic aromatic fluorination.
Scheme 7: Examples of [18F]-radiolabeled molecular imaging probes.
Scheme 8: Flow microreactor synthesis of dipeptides.
Scheme 9: Flow synthesis involving SNAr reactions.
Scheme 10: Flow synthesis of fluoroquinolone antibiotics.
Scheme 11: Highly controlled formation of PFPMgBr.
Scheme 12: Selective flow synthesis of photochromic diarylethenes.
Scheme 13: Flow microreactor system for perfluoroalkylation by generation of perfluoroalkyllithiums in the pre...
Scheme 14: Integrated flow microreactor system for perfluoroalkylation by generation of perfluoroalkyllithiums...
Graphical Abstract
Figure 1: Exploring the effect of fluorine incorporation in triazolium pre-catalysts (2) for the enantioselec...
Figure 2: Target triazolium salts 5–10 for this study. The synclinal-endo conformation of 5 is shown [18]. Only t...
Scheme 1: Synthesis of the difluorinated triazolium salt 7 starting from commercially available N-Boc-trans-4...
Scheme 2: Synthesis of the monofluorinated triazolium salt 8.
Scheme 3: Synthesis of the trifluoromethylated and non-fluorinated pre-catalysts 9 and 10 for control studies....
Figure 3: X-ray crystal structures of triazolium salts 5·BF4−, 6·BF4− and 7·BF4− [42]. The tetrafluoroborate coun...
Figure 4: An overview of the molecular editing approach to catalyst development.
Graphical Abstract
Scheme 1: Transition metal-mediated methods for the preparation of (trifluoroethyl)arenes.
Scheme 2: Cu-mediated trifluoromethylation of benzyl methanesulfonates. Reaction conditions: 1 (2.0 mmol), Cu...
Scheme 3: Cu-Mediated trifluoromethylation of allyl methanesulfonates.
Scheme 4: Cu-Mediated trifluoromethylation of propargyl methanesulfonates.
Graphical Abstract
Figure 1: Electrophilic trifluoromethylating agents 1 and 2.
Scheme 1: Synthesis of 5-nitro-1-(trifluoromethyl)-3H-1λ3,2-benziodaoxol-3-one (3).
Figure 2: UV–vis spectra of reagents 2 (green) and 3 (blue) in DMSO/H2O 1:1.
Figure 3: ORTEP representation of X-ray structures 6 and 3. Thermal ellipsoids set to 30% probability. Hydrog...
Figure 4: DSC traces obtained for 2 (green) and 3 (blue).
Figure 5: Cyclic voltammetry of 3 (1 mM, black) and of a mixture of 3 (1 mM) and methyl 2-iodo-5-nitrobenzoat...
Figure 6: Sample kinetic traces for the decomposition of 2 (green) and 3 (blue) to 4 and 5, respectively, upo...
Graphical Abstract
Figure 1: The CF2 group in 1c accelerates RCM reactions relative to CHF (1d) and CH2 (1e) and with a similar ...
Figure 2: X-ray structures of a) 1,1,4,4- (3) b) 1,1,7,7- (4) and c) 1,1,6,6- (5) tetrafluorocyclododecanes. ...
Figure 3: Synthesis targets: Palmitic acid analogues 6a–c.
Scheme 1: Synthesis route to 8,8-difluorohexadecanoic acid (6a).
Scheme 2: The synthesis of palmitic acid analogues 6b and 6c.
Figure 4: DSC traces for the three palmitic acid analogues 6a–c.
Figure 5: The X-ray crystal structures of 8,8-difluorohexadecanoic acid (6a).
Figure 6: The X-ray structure of 8,8,11,11-tetrafluorohexadecanoic acid (6c).
Scheme 3: Synthesis route to the tetrafluorinated alkane 27.
Figure 7: The X-ray structure of 8,8,11,11-tetrafluorononadecane (27).
Figure 8: Conformational interconversion of 1,4-di-CF2 motif.
Graphical Abstract
Scheme 1: Organocatalytic enantioselective fluorination of α-chloroaldehyde 2a [8].
Scheme 2: Determination of absolute configuration of α-chloro-α-fluoro-β-keto ester 6 by X-ray analysis [9].
Scheme 3: Transformation of α-chloro-α-fluoro-β-keto ester 6 to chlorofluoro alcohol 4a.
Scheme 4: Proposed reaction mechanism.
Scheme 5: Fluorination of the enantiomers of 2a.
Scheme 6: Enantioselective fluorination of α-branched aldehyde 12.
Graphical Abstract
Scheme 1: Various procedures for the generation of difluoromethylene phosphonium ylide [19-25].
Scheme 2: Difluoromethylenation of alkenes and alkynes and difluoromethylation of heteroatom nucleophiles wit...
Scheme 3: Bromo–chloro exchange reaction using AgCl.
Scheme 4: Proposed different reaction pathways of the difluorinated ylide in the presence of TMSCl and TMSBr.
Figure 1: gem-Difluoroolefination of aldehydes. Reactions were performed on 0.5 mmol scale in a pressure tube...
Figure 2: gem-Difluoroolefination of activated ketones. Reactions were performed on 0.5 mmol scale in a press...
Scheme 5: Plausible mechanisms for the formation of difluoromethylene triphenylphosphonium ylide from TMSCF2C...
Graphical Abstract
Scheme 1: Synthesis of (trifluoromethyl)phosphinic acid (1) and ethyl and isopropyl esters 2–4. Reagents and ...
Scheme 2: Three-component Kabachnik–Fields reaction of CF3(H)P(O)(OiPr) (2) with formaldehyde and dibenzylami...
Scheme 3: Three-component synthesis of CF3 containing α-aminophosphinic acids 14a,b. Reagents and conditions:...
Scheme 4: Interaction of the acid 1 with tert-butyl benzylidenecarbamate (21). Reagents and conditions: i) an...
Scheme 5: Interaction of the acids 1 and 6 with ethyl 2-[(tert-butoxycarbonyl)imino]acetate (22). Reagents an...
Scheme 6: Transformation of the ester 24 into the appropriate free acid 25. Reagents and conditions: i) two f...
Scheme 7: Reaction of the acids (1) and (6) with methyl 2-imino-3-methylbutanoate (26). Reagents and conditio...
Scheme 8: Interaction of the acid 1 with ethyl 2-(tert-butoxycarbonylamino)acrylate (29). Reagents and condit...
Scheme 9: Interaction of a mixture of the esters 3 and 4 with 2-acetamidoacrylic acid (33). Reagents and cond...
Scheme 10: Interaction of a mixture of the acid 1 with diethyl acetaminomethylenemalonate (38). Reagents and c...
Graphical Abstract
Scheme 1: SNAr reaction of 2-fluoronitrobenzene (2a) with diethyl 2-fluoromalonate (1).
Figure 1: Molecular structure of 3.
Scheme 2: Synthesis of benzyl fluoride derivative 5.
Figure 2: Molecular structure of methyl ester 6a.
Scheme 3: Synthesis of pyridyl fluoride 7.
Figure 3: Molecular structure of 7.