434-90-2Relevant academic research and scientific papers
Ullmann reaction optimization within bitolyl and decafluorobiphenyl synthesis
Kolotaev,Razinov,Khachatryan
, p. 993 - 999 (2018)
This article describes the investigation of the cross-coupling Ullman's reaction of aryl halides under various conditions to find optimal scalable method of biaryl synthesis and the development of preparative methods of synthesizing 3,3'-bitolyl and perfluorobipfenyl, which are valuable semi-products of organic synthesis.
Intriguing Behavior of an Apparently Simple Coupling Promoter Ligand, PPh2(p-C6H4-C6F5), in Their Pd Complexes
Pérez-Iglesias, María,Infante, Rebeca,Casares, Juan A.,Espinet, Pablo
, p. 3688 - 3695 (2019)
Ligand PPh2(p-C6H4-C6F5), LHF, is an example of monodentate biphenyl phosphine that allows for cis coordination of two phosphines to Pd, as in complex cis-[PdPf2Pd(LHF)2] (A) (Pf = C6F5). At 25 °C, complex A undergoes easy reductive elimination to decafluorobiphenyl and, competitively, isomerizes to trans-[Pd(C6F5)2Pd(LHF)2] via functionally three-coordinate intermediates cis-[PdPf2(LHF)(S)] with the fourth position empty or weakly protected (S= THF, OH2, or π-aryl). Unexpectedly, the direct reductive C6F5-C6F5 elimination is faster from the four-coordinate complex A than from the intermediates with only one strong LHF. The reason for this is that two cis LHF ligands play the role of a chelate with a large bite angle and some tetrahedral distortion. As a matter of fact, using LHF in excess (Pd:L ? 1:2), a Pf-Pf coupling barrier ΔG?Pf-Pf = 23.1 kcal·mol-1 is measured, which ranks its efficiency for coupling and formation of the corresponding Pd0 catalyst as better than XantPhos or PhPEWO-F and about the same as tBuBrettPhos. On the other hand, complex (μ-Cl)2[Pd2Rf2(LHF)2] (B) (Rf = C6F3Cl2 = 3,5-dichloro-2,4,6-trifluorophenyl), obtained by reaction of (μ-Cl)2[Pd2Rf2(tht)2] (tht = tetrahydrothiophene) with LHF, presents in the 19F NMR COSY spectrum a very intriguing through-space coupling pattern of the Fortho atoms of the C6F5 group in LHF and the 3-5-C6F3Cl2 group on Pd. The intermittent coupling mechanism proposed is based on the switching of π-π-stacking of C6F5 from one Ph group to another Ph group of LHF, which gives rise to enantiomers at the chiral P atom. Rotation around the P-biphenyl bond under hindered rotation around the C-C6F5 bond produces the intriguing selective coupling observed.
Selective reductive defluorination of dicyclohexyl compounds: Intramolecular coupling reaction by reductive cleavage of C-F bonds
Sung, Kuangsen,Lagow, Richard J.
, p. 637 - 638 (1998)
Reductive defluorination of perfluoro(dicyclohexyl ether) 1 with benzophenone anion radical in tetrahydrofuran produces perfluoro(dibenzofuran) 2 with a surprising ring-closure, whereas reductive defluorination of perfluoro(dicyclohexyl) 4 under the same conditions gives perfluoro(diphenyl) 6 with no products involving ring-closure.
Pentafluorophenyl transfer: A new group-transfer reaction in organoborate salts
Hewavitharanage, Priyadarshine,Danilov, Evgeny O.,Neckers, Douglas C.
, p. 10653 - 10659 (2005)
Irradiation of isoquinolinium hydroxytris(pentafluorophenyl)borate, 1, and phenanthridium hydroxytris(pentafluorophenyl)borate, 2, in either CH 2Cl2 or CH3CN resulted in C6F 5 transfer to the isoquinolinium and phenanthridium cations, generating 2-methyl-1-(2,3,4,5,6- pentafluorophenyl)-1,2-dihydroisoquinoline, 3, and 2-methyl-1-(2,3,4,5,6-pentafluorophenyl)-1,2-dihydrophenanthridine, 4, respectively. In addition, photogeneration of H2O·B(C 6F5)3 resulted from 1. Photogeneration of C6F5-C6F4H from HO-B(C 6F5)3- and of C6H 5-C6F4H from C6H5- B(C6F5)3- was discovered.
Convenient Synthesis of Symmetrical Polyfluorinated Diphenyl Sulfides
Bredikhin, R. A.,Maksimov, A. M.,Nikul’shin, P. V.,Platonov, V. E.
, p. 1921 - 1930 (2022/01/24)
Abstract: Thermal properties of decafluorodiphenyl disulfide in the pure state and in the presence of copper and iron metals have been studied. A procedure has been proposed for the synthesis of symmetrical poly-fluorinated diaryl sulfides from diaryl dis
Selective synthesis of fluorinated biaryls by [MCl2(PhPEWO-F)] (M = Ni, Pd) catalysed Negishi cross-coupling
Espinet, Pablo,Ponce-De-León, Jaime
supporting information, p. 10875 - 10878 (2021/10/22)
Highly selective cross-couplings to polyfluorinated assymmetric biaryls, including the symmetric biaryl C6F5-C6F5, are achieved at relatively low temperature (80 °C) and in short times using [MCl2(PhP
Palladium-Catalyzed Homocoupling of Highly Fluorinated Arylboronates: Studies of the Influence of Strongly vs Weakly Coordinating Solvents on the Reductive Elimination Process
Budiman, Yudha P.,Friedrich, Alexandra,Jayaraman, Arumugam,Kerner, Florian,Marder, Todd B.,Radius, Udo
supporting information, p. 6036 - 6050 (2020/04/27)
C-C reductive elimination from [PdL2(C6F5)2] to form polyfluorinated biaryls has been a challenge for over 50 years. Thus, palladium-catalyzed homocoupling of arylboronates (ArF-Bpin) containing two ortho-fluorine substituents is very difficult, as the reaction typically stops at the [PdL2(ArF)2] stage after two transmetalation steps. The transmetalated complexes cis-[Pd(MeCN)2(C6F5)2] (3a), cis-[Pd(MeCN)2(2,4,6-C6F3H2)2] (3b), and cis-[Pd(MeCN)2(2,6-C6F2H3)2] (3e) have been isolated from the reaction of ArF-Bpin with Pd(OAc)2 in acetonitrile solvent, with no homocoupling observed. However, catalytic homocoupling proceeds smoothly in a "weakly coordinating" arene solvent as long as no ancillary ligands or coordinating solvents are present. DFT computations reveal that the active catalyst formed by arene solvent coordination leads to an overall reduced barrier for the reductive elimination step compared to the formation of stable [PdL2(ArF)2] complexes in the presence of a donor ligand or solvent L.
Discovery and mechanistic investigation of Pt-catalyzed oxidative homocoupling of benzene with PhI(OAc)2
Abu-Omar, Mahdi M.,Nabavizadeh, S. Masoud,Niroomand Hosseini, Fatemeh,Park, Chan,Wu, Guang
supporting information, p. 2477 - 2486 (2020/03/05)
We present a Pt-catalyzed direct coupling of benzene to biphenyl. This catalytic reaction employs a cyclometalated platinum(ii) complex [PtMe(bhq)(SMe2)] (bhq = benzo[h]quinolate) with PhI(OAc)2 as an oxidant and does not require an acid, a co-catalyst or a solvent. The reaction kinetics and characterization of potential catalytic species are reported. The reaction is first-order in Pt and second-order in benzene, which implicates the second C-H activation step as rate-determining. A Pt(ii)/Pt(iv) catalytic cycle is suggested. The reaction commences by oxidation of the Pt(ii) complex to give the platinum(iv) species [Pt(bhq)(SMe2)(OAc)2](OAc) followed by C-H activation of benzene to afford the intermediate [PtPh(bhq)(SMe2)(OAc)](OAc) concurrently with the release of HOAc. A second benzene molecule reacts similarly to give the diphenyl intermediate [PtPh2(bhq)(SMe2)](OAc). C-C bond forming reductive elimination ensues to regenerate Pt(ii) and complete the catalytic cycle. The proposed mechanism has been examined by DFT computations, which provide support to experimental findings.
Ranking Ligands by Their Ability to Ease (C6F5)2NiIIL → Ni0L + (C6F5)2Coupling versus Hydrolysis: Outstanding Activity of PEWO Ligands
Ponce-De-León, Jaime,Gioria, Estefania,Martínez-Ilarduya, Jesús M.,Espinet, Pablo
supporting information, p. 18287 - 18294 (2020/12/23)
The NiII literature complex cis-[Ni(C6F5)2(THF)2] is a synthon of cis-Ni(C6F5)2 that allows us to establish a protocol to measure and compare the ligand effect on the NiII → Ni0 reductive elimination step (coupling), often critical in catalytic processes. Several ligands of different types were submitted to this Ni-meter comparison: Bipyridines, chelating diphosphines, monodentate phosphines, PR2(biaryl) phosphines, and PEWO ligands (phosphines with one potentially chelate electron-withdrawing olefin). Extremely different C6F5-C6F5 coupling rates, ranging from totally inactive (producing stable complexes at room temperature) to those inducing almost instantaneous coupling at 25 °C, were found for the different ligands tested. The PR2(biaryl) ligands, very efficient for coupling in Pd, are slow and inefficient in Ni, and the reason for this difference is examined. In contrast, PEWO type ligands are amazingly efficient and provide the lowest coupling barriers ever observed for NiII complexes; they yield up to 96% C6F5-C6F5 coupling in 5 min at 25 °C (the rest is C6F5H) and 100% coupling with no hydrolysis in 8 h at-22 to-53 °C.
E- Z Isomerization of Phosphine-Olefin (PEWO-F4) Ligands Revealed upon PdCl2 Capture: Facts and Mechanism
Pe?as-Defrutos, Marconi N.,Vélez, Andrea,Gioria, Estefanía,Espinet, Pablo
supporting information, p. 4701 - 4707 (2019/12/24)
The PEWO phosphines R2P(o-C6H4CH-CHC(O)Ph), R2P(o-C6H2F2CH-CHC(O)Ph), and R2P(o-C6F4CH-CHC(O)Ph) and their P-monodentate complexes trans-[PdCl2(P-monodentate)2] show, in solution and (when available) in the X-ray diffraction structures, an E configuration of the double bond. In contrast, the structures of [PdCl2(P-chelate)] display E and Z configurations. The E/Z isomerization of the latter requires first decoordination of the double bond, which then allows for easy rotation about the electron-deficient double bond. Thus, the E/Z equilibria exist for the free and the P-monodentate complexes as well but are not observed because they are extremely displaced toward the E isomer. Their capture in the form of [PdCl2(P-chelate)], with equilibrium constants on the order Keq ≈ 1-3, allows the two configurations to be observed and isolated. Evaluation of their ability to couple Pf-Pf from cis-[PdPf2(THF)2] (Pf = C6F5) affords values of their ΔG?(Pf-Pf)Pd parameters confirming that higher substitution of H by F produces lower coupling barriers and a double bond that is more electron deficient when it is free and more electron withdrawing when it is coordinated.
