The introduction of fluorine into organic molecules is widely practised particularly when tuning the properties of molecules for specialist functions. Fluorine substitution finds a prominent role in pharmaceutical development, in governing bioactivity in a wide range of agrochemical products, in soft materials chemistry such as liquid crystals, in photoresist polymers, self assembling monolayers and in positron emission tomography. Allied to this breadth of activity is a steady development in the number and range of fluorination reagents and methods. The changes in behaviour of a molecule after the introduction of a fluorine atom continue to be unpredictable, and understanding such behaviour remains a driver in organo-fluorine research. Contributions to this series come from an international grouping of noted experts in fluorine chemistry, covering a wide range of topics, including the chemistry of trifluoromethyl compounds, the enantioselective synthesis of organo-fluorine compounds, the synthesis of fluorinated derivatives of natural products and the preparation of organo-fluorine compounds by Michael addition.
See also the Thematic Series:
Organo-fluorine chemistry III
Organo-fluorine chemistry II
See organo-fluorine videos at Beilstein TV.
Graphical Abstract
Figure 1: Natural sphingosines 1a, 2a and synthesized fluorinated analogues 1b, 2b.
Scheme 1: Synthesis of 4-fluorosphingosine (2b); Reagents: i ClTi(OEt)3/Et3N, CH2Cl2, 13 h, 0 °C; ii 15% aq c...
Scheme 2: Mechanism of the aldol reaction.
Figure 2: Favorable conformations of the tert-butyl amino acid ester 7.
Figure 3: π–A Isotherms of ceramide (2a) and 4-fluoroceramide (2b) at 20 °C (80 cm2/min compression velocity)....
Figure 4: Cycles of compression and expansion for ceramide (2a) and 4-fluoroceramide (2b).
Graphical Abstract
Figure 1: OCF3-bearing pesticides.
Scheme 1: Preparation of trifluoromethyl ethers via a chlorination/fluorination sequence.
Scheme 2: Preparation of trifluoromethyl ethers via an in situ chlorination/fluorination sequence.
Scheme 3: Preparation of trifluoromethyl ethers via chlorothionoformates.
Scheme 4: Preparation of trifluoromethyl ethers via fluoroformates.
Scheme 5: Oxidative desulfurization-fluorination toward trifluoromethyl ethers.
Scheme 6: Mechanism of the oxidative desulfurization-fluorination.
Scheme 7: Umemoto's O-(trifluoromethyl)dibenzofuranium salts 4 as CF3-transfer agents.
Scheme 8: Togni's approach using hypervalent iodine compounds as CF3-transfer agents.
Scheme 9: TAS OCF3 as a nucleophilic OCF3-transfer agent.
Figure 2: Mesomeric structures of the OCF3-group.
Figure 3: Structures of 6 and 7.
Figure 4: Conformational preference of the trifluoromethoxy group on aryl rings.
Scheme 10: Nitration of trifluoromethoxy benzene.
Scheme 11: Synthesis and Nitration of N-Acetyl-(trifluoromethoxy)anilines.
Scheme 12: Bromine/lithium exchange of bromo(trifluoromethoxy)benzenes.
Scheme 13: Metalation of (trifluoromethoxy)benzene.
Scheme 14: Metalation of (trifluoromethoxy)naphthalenes.
Scheme 15: Competition between -CF3- and -OCF3 in Metalation reactions.
Scheme 16: Competition between -F- and -OCF3 in Metalation reactions.
Scheme 17: Metalation of trifluoromethoxyanisoles.
Figure 5: Direction of π-polarization depending on the substituent as described by Schlosser et al. [57].
Scheme 18: Metalation of Bromo(trifluoromethoxy)benzenes.
Scheme 19: Aryne formation from bromo(trifluoromethoxy)phenyllithiums and subsequent Diels-Alder cycloaddition...
Scheme 20: Metalation of (trifluoromethoxy)anilines.
Graphical Abstract
Figure 1: Structures of DBFOX-Ph, Box-Ph and NFSI.
Scheme 1: Transition-State Structure for the DBFOX-Ph/Ni(II) Catalyzed Enantioselective Fluorination of 1 to 2...
Graphical Abstract
Scheme 1: Reaction mechanism for phosphine catalyzed 1,4-addition to α,β-unsaturated compounds.
Graphical Abstract
Scheme 1: Pd-catalyzed allylic substitution of the gem-difluorinated allylic carbonates 1 and 4.
Scheme 2: Synthesis of trans-trans dimer 8 and syn-syn dimer 9.
Figure 1: X-ray structure of trans-trans dimer 8.
Scheme 3: Reaction of trans-trans dimer 8 with 3-benzoylthymine sodium / PPh3.
Scheme 4: Reaction of trans-trans dimer 8 with PPh3 / AgSbF6.
Graphical Abstract
Scheme 1: Synthetic approach to the trifluoromethyl triazoles.
Figure 1: Experimentally found NOE correlation for compound 2c.
Scheme 2: Cycloaddition of enantiopure propargylamine.
Graphical Abstract
Scheme 1: Structure of chiral quaternary ammonium salts.
Scheme 2: Determination of the absolute configuration of (+)-3a.
Graphical Abstract
Figure 1: Pharmaceuticals with pyrimidine sub-units.
Scheme 1: Use of 2,4,6-trichloropyrimidine as a core scaffold. Reagents and Conditions: a) bis(4-methoxybenzy...
Scheme 2: Reaction of 1 with benzamidine.
Figure 2: Molecular structure of 3g.
Graphical Abstract
Figure 1: Calix[4]arene in cone conformation.
Scheme 1: Preparation of 3a and 3b.
Scheme 2: Preparation of 4 and 5.
Scheme 3: Preparation of 6.
Scheme 4: Preparation of 8 and 9.
Figure 2: Full (top), top (bottom left)a, and side (bottom right)a views of 5; afluorous chains omitted for c...