16297-19-1Relevant articles and documents
Halogen Bonds of Halotetrafluoropyridines in Crystals and Co-crystals with Benzene and Pyridine
Schwabedissen, Jan,Trapp, Pia C.,Stammler, Hans-Georg,Neumann, Beate,Lamm, Jan-Hendrik,Vishnevskiy, Yury V.,K?rte, Leif A.,Mitzel, Norbert W.
, p. 7339 - 7350 (2019)
The structures of the three para-substituted halotetrafluoropyridines with chlorine, bromine, and iodine have been determined in the solid state (X-ray diffraction). The structures of these compounds and that of pentafluoropyridine were also determined in the gas phase (electron diffraction). Structures in the solid state of the bromine and iodine derivatives exhibit halogen bonding as a structure-determining motif. On the way to an investigation of halogen bond formation of halotetrafluoropyridines in the solid state with the stronger Lewis base pyridine, co-crystals of benzene adducts were investigated to gain an understanding of the influence of aryl–aryl interactions. These co-crystals showed halogen bonding only for the two heavier halotetrafluoropyridines. In the pyridine co-crystals halogen bonding was observed for all three para-halotetrafluoropyridines. The formation of homodimers and heterodimers with pyridine is also supported by quantum-chemical calculations of electron density topologies and natural bond orbitals.
Synthesis of Polyflourinated Biphenyls; Pushing the Boundaries of Suzuki-Miyaura Cross Coupling with Electron-Poor Substrates
Bulfield, David,Huber, Stefan M.
, p. 13188 - 13203 (2017/12/26)
Polyfluorinated biphenyls are interesting and promising substrates for many different applications. Unfortunately, all current methods for the syntheses of these compounds only work for a hand full of molecules or only in very special cases. Thus, many of these compounds are still inaccessible to date. Here we report a general strategy for the synthesis of a wide range of highly fluorinated biphenyls. In our studies we investigated crucial parameters, such as different phosphine ligands and the influence of various nucleophiles and electrophiles with different degrees of fluorination. These results extend the scope of the already very versatile Suzuki-Miyaura reaction toward the synthesis of very electron-poor products, making these more readily accessible. The presented methodology is scalable and versatile without the need for elaborate phosphine ligands or Pd-precatalysts.
Preparation of p-substituted tetrafluoropyridyl derivatives via the tetrafluoropyridylcopper reagent
Van Nguyen, Ba,Burton, Donald J.
, p. 144 - 154 (2012/03/27)
A new and improved preparation of 4-iodo-2,3,5,6-tetrafluoropyridine from pentafluoropyridine is described. This iodopyridine is utilized for the in situ preparation of the 4-tetrafluoropyridylcopper reagent, 1, via two methods. The first method involves metathesis of the 4-tetrafluoropyridylcadmium reagent with Cu(I)Br at room temperature. The requisite cadmium reagent was readily prepared in situ via reaction between 4-iodotetrafluoropyridine with acid-washed cadmium powder in DMF at room temperature. The second method involves the in situ reaction of 4-tetrafluoropyridyltributyl-phosphonium tetrafluoroborate with Na2CO3 and Cu(I)Br in DMF at room temperature. 1 readily undergoes reaction with allylic halides, vinyl iodides, aryl halides, acid chlorides and acetylenic iodides at room temperature to stereospecifically afford the corresponding 4-tetrafluoropyridyl derivatives. An alternative route to the alkyne derivatives was developed via the Pd(0) catalyzed reaction of 4-iodotetrafluoropyridine with 1-alkynes.
From hypervalent xenon difluoride and aryliodine(III) difluorides to onium salts: Scope and limitation of acidic fluoroorganic reagents in the synthesis of fluoroorgano xenon(II) and iodine(III) onium salts
Abo-Amer, Anwar,Frohn, Hermann-Josef,Steinberg, Christoph,Westphal, Ulrich
, p. 1311 - 1323 (2008/12/21)
Fluorinated organodifluoroboranes RfBF2 are in general suitable reagents to transform XeF2 and RIF2 into the corresponding onium tetrafluoroborate salts [RfXe][BF4] and [R(Rf)I][BF4], respectively. (4-C5F4N)BF2 and trans-CF3CF{double bond, long}CFBF2 which represent boranes of high acidity form no Xe-C onium salts in reactions with XeF2 but give the desired iodonium salts with RIF2 (R = C6F5, o-, m-, p-C6FH4). The reaction of (4-C5F4N)BF2 with XeF2 ends with a XeF2-borane adduct. C6F5Xe(4-C5F4N), the first Xe-(4-C5F4N) compound, was obtained when C6F5XeF was reacted with Cd(4-C5F4N)2. We describe the synthesis of (4-C5F4N)IF2 and reactions of (4-C5F4N)IF2 and C6F5IF2 with (4-C5F4N)BF2. Analogous to [(4-C5F4N)2I][BF4] and [C6F5(4-C5F4N)I][BF4] aryl(perfluoroalkenyl)iodonium salts [R(R′)I][BF4] were obtained from RIF2 (R = C6F5, o-, m-, p-C6FH4) and R′BF2 (R′ = trans-CF3CF{double bond, long}CF, CF2{double bond, long}CF). The gas phase fluoride affinities pF- of selected fluoroorganodifluoroboranes RfBF2 and their hydrocarbon analogs are calculated (B3LYP/6-31+G*) and discussed with respect to their potential to introduce Rf-groups into hypervalent EF2 bonds. Four aspects which influence the transformation of hypervalent EF2 bonds (E = Xe, R′I) under the action of Lewis acidic reagents RAFn-1 (A = B, P; n = 3, 5) into the corresponding [RE][AFn+1] salts are presented and the important role of the acidity is emphasized. Fluoride affinities may help to plan the introduction of organo groups into EF2 moieties and to expand the types of acidic reagents. Thus C6H5PF4 with a pF- value comparable to that of RfBF2 compounds is able to introduce the C6H5 group into RIF2 (R = C6F5, p-C6FH4).
