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1.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(51):16556-16559
Functionalization reactions of the refrigerants HFO‐1234yf (2,3,3,3‐tetrafluoropropene) and HFO‐1234ze (1,3,3,3‐tetrafluoropropene) were developed. The selectivity and reactivity towards CF3 groups of C−F activation reactions can be controlled by employing either a germane or a silane as the hydrogen source. Unique transformations were designed to accomplish consecutive hydrogermylation and C−F activation steps. This allowed for an unprecedented transformation of an olefinic C−F bond into a C−H bond by heterogeneous catalysis. These reactions are catalyzed by nanoscopic aluminum chlorofluoride (ACF) under very mild conditions. 相似文献
2.
C–F activation of 2,3,5,6-tetrafluoropyridine at [Rh{Si(OEt)3}(PEt3)3] (1) yields [Rh{2-(3,5,6-C5F3HN)}(PEt3)3] (2) and FSi(OEt)3, but in an unprecedented consecutive reaction FSi(OEt)3 acts as a fluoride source to give [Rh(4-C5F4N)(PEt3)3] (4) by regeneration of the C–F bond and C–H activation. Analogous refluorination steps were observed for other 2-pyridyl rhodium complexes. NMR spectroscopic studies revealed a delicate balance between the feasibility for C–F bond formation accompanied by a C–H activation and the occurrence of competing reactions such as hydrodefluorinations induced by the intermediary presence of H2. 相似文献
3.
Dr. Maria Talavera Prof. Dr. Thomas Braun 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(46):11926-11934
The reaction of the rhodium(I) complexes [Rh(E)(PEt3)3] (E=GePh3 ( 1 ), H ( 6 ), F ( 7 )) with 1,1,3,3,3-pentafluoropropene afforded the defluorinative germylation products Z/E-2-(triphenylgermyl)-1,3,3,3-tetrafluoropropene and the fluorido complex [Rh(F)(CF3CHCF2)(PEt3)2] ( 2 ) together with the fluorophosphorane E-(CF3)CH=CF(PFEt3). For [Rh(Si(OEt)3)(PEt3)3] ( 4 ) the coordination of the fluoroolefin was found to give [Rh{Si(OEt)3}(CF3CHCF2)(PEt3)2] ( 5 ). Two equivalents of complex 2 reacted further by C−F bond oxidative addition to yield [Rh(CF=CHCF3)(PEt3)2(μ-F)3Rh(CF3CHCF2)(PEt3)] ( 9 ). The role of the fluorido ligand on the reactivity of complex 2 was assessed by comparison with the analogous chlorido complex. The use of complexes 1 , 4 and 6 as catalysts for the derivatization of 1,1,3,3,3-pentafluoropropene provided products, which were generated by hydrodefluorination, hydrometallation and germylation reactions. 相似文献
4.
Dr. Richard D. Adams Dr. Vitaly Rassolov Dr. Yuen Onn Wong 《Angewandte Chemie (International ed. in English)》2016,55(4):1324-1327
The electronically unsaturated dirhenium complex [Re2(CO)8(μ‐H)(μ‐Ph)] ( 1 ) has been found to exhibit aromatic C?H activation upon reaction with N,N‐diethylaniline, naphthalene, and even [D6]benzene to yield the compounds [Re2(CO)8(μ‐H)(μ‐η1‐NEt2C6H4)] ( 2 ), [Re2(CO)8(μ‐H)(μ‐η2‐1,2‐C10H7)] ( 3 ), and [D6]‐ 1 , respectively, in good yields. The mechanism has been elucidated by using DFT computational analyses, and involves a binuclear C?H bond‐activation process. 相似文献
5.
Cross‐Coupling of Organolithium with Ethers or Aryl Ammonium Salts by C−O or C−N Bond Cleavage 下载免费PDF全文
Ze‐Kun Yang Dong‐Yu Wang Hiroki Minami Hiroyuki Ogawa Takashi Ozaki Dr. Tatsuo Saito Dr. Kazunori Miyamoto Dr. Chao Wang Prof. Dr. Masanobu Uchiyama 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(44):15693-15699
Various aryl‐, alkenyl‐, and/or alkyllithium species reacted smoothly with aryl and/or benzyl ethers with cleavage of the inert C?O bond to afford cross‐coupled products, catalyzed by commercially available [Ni(cod)2] (cod=1,5‐cyclooctadiene) catalysts with N‐heterocyclic carbene (NHC) ligands. Furthermore, the coupling reaction between the aryllithium compounds and aryl ammonium salts proceeded under mild conditions with C?N bond cleavage in the presence of a [Pd(PPh3)2Cl2] catalyst. These methods enable selective sequential functionalizations of arenes having both C?N and C?O bonds in one pot. 相似文献
6.
Dr. Hajime Kameo Tatsuya Kawamoto Prof. Shigeyoshi Sakaki Prof. Didier Bourissou Prof. Hiroshi Nakazawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(7):2370-2375
Si?F bond cleavage of fluoro‐silanes was achieved by transition‐metal complexes under mild and neutral conditions. The Iridium‐hydride complex [Ir(H)(CO)(PPh3)3] was found to readily break the Si?F bond of the diphosphine‐ difluorosilane {(o‐Ph2P)C6H4}2Si(F)2 to afford a silyl complex [{[o‐(iPh2P)C6H4]2(F)Si}Ir(CO)(PPh3)] and HF. Density functional theory calculations disclose a reaction mechanism in which a hypervalent silicon species with a dative Ir→Si interaction plays a crucial role. The Ir→Si interaction changes the character of the H on the Ir from hydridic to protic, and makes the F on Si more anionic, leading to the formation of Hδ+???Fδ? interaction. Then the Si?F and Ir?H bonds are readily broken to afford the silyl complex and HF through σ‐bond metathesis. Furthermore, the analogous rhodium complex [Rh(H)(CO)(PPh3)3] was found to promote the cleavage of the Si?F bond of the triphosphine‐monofluorosilane {(o‐Ph2P)C6H4}3Si(F) even at ambient temperature. 相似文献
7.
Greg Coates Hui Yee Tan Carolin Kalff Andrew J. P. White Mark R. Crimmin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(36):12644-12648
A number of new magnesium and lithium silyl reagents were prepared and shown to be outstanding nucleophiles in reactions with industrially relevant fluoroolefins. These reactions result in a net transformation of either sp2 or sp3 C?F bonds into C?Si bonds by two modes of nucleophilic attack (SNV or SN2′). The methods are mild, proceeding with high chemo‐ and regioselectivity. Mechanistic pathways are described that lead to new substitution patterns from HFO‐1234yf, HFO‐1234ze, and HFO‐1336mzz, previously inaccessible by transition metal catalyzed difluorosilylation routes. 相似文献
8.
[RhH(CO)(PPh3)2] (1) reacts with Et3N·3HF to give the fluoro compound [RhF(CO)(PPh3)2] (2). In a comparable reaction [RhF(PEt3)3] (5) has been obtained from [RhH(PEt3)3] (3) or [RhH(PEt3)4] (4) with substoichiometric amounts of Et3N·3HF in THF. If the latter reaction is carried out in benzene, the complexes 5, cis-mer-[Rh(H)2F(PEt3)3] (6) and cis-fac-[Rh(H)2F(PEt3)3] (7) are obtained. Treatment of 5 with HCl in ether effects the generation of [RhCl(PEt3)3] (8) and the bifluoride compound [Rh(FHF)(PEt3)3] (9), which can be converted into 5 in the presence of Et3N and Cs2CO3. Treatment of 5 with HSiR2Ph (R=Ph, Me) leads to the formation of 3 and the rhodium(III) silyl complexes fac-[Rh(H)2(SiR2Ph)(PEt3)3] (10: R=Ph, 11: R=Me). 相似文献
9.
The complex [Rh(η3‐benzyl)(dippe)] ( 1 ; dippe=bis(diisopropylphosphino)ethane=(ethane‐1,2‐diyl)bis[diisopropylphosphine]) reacted cleanly with Mes*PH2 ( 2 ; Mes*=2,4,6‐tBu3C6H2) to provide a new Rh species [Rh(H)(dippe)(L)] ( 3 ), L being the 2,3‐dihydro‐3,3‐dimethyl‐1H‐phosphindole ligand 4 (=tBu2C6H2(CMe2CH2PH)) (Scheme 1). Complex 3 was converted to the corresponding chloride [Rh(Cl)(dippe)(L)] ( 6 ) when treated with CH2Cl2, whereas the dimeric species [Rh2{μ‐tBu2C6H2(CMe2CH2P)}(μ‐H)(dippe)2] ( 7 ) was formed upon thermolysis in toluene (Scheme 2). The structures of 6 and 7 ⋅C7H8 were determined by X‐ray crystallography. Complexes 1 and 3 served as catalyst precursors for the dehydrogenative coupling of C−H and P−H bonds in the conversion of 2 to 4 (Scheme 3). Deuteration studies with Mes*PD2 exposed a complex series of bond‐activation pathways that appear to involve C−H activation of the dippe ligand by the Rh‐atom (Schemes 4 and 5) 相似文献
10.
Catalytic Borylation of SCF3‐Functionalized Arenes by Rhodium(I) Boryl Complexes: Regioselective CH Activation at the ortho‐Position 下载免费PDF全文
Dipl.‐Chem. Sabrina I. Kalläne Prof. Dr. Thomas Braun 《Angewandte Chemie (International ed. in English)》2014,53(35):9311-9315
An unprecedented reaction pathway for the borylation of SCF3‐containing arenes using [Rh(Bpin)(PEt3)3] (pin=pinacolato) is reported. Catalytic processes were developed and the functionalizations proceed under mild reaction conditions. The C? H activations occur with a unique regioselectivity for the position ortho to the SCF3 group, which apparently serves as directing group. Borylated SCF3 compounds can serve as versatile building blocks. 相似文献
11.
A Cobalt(I) Pincer Complex with an η2‐Caryl−H Agostic Bond: Facile C−H Bond Cleavage through Deprotonation,Radical Abstraction,and Oxidative Addition 下载免费PDF全文
Sathiyamoorthy Murugesan Dr. Berthold Stöger Dr. Ernst Pittenauer Prof. Dr. Günter Allmaier Prof. Dr. Luis F. Veiros Prof. Dr. Karl Kirchner 《Angewandte Chemie (International ed. in English)》2016,55(9):3045-3048
The synthesis and reactivity of a CoI pincer complex [Co(?3P,CH,P‐P(CH)PNMe‐iPr)(CO)2]+ featuring an η2‐ Caryl?H agostic bond is described. This complex was obtained by protonation of the CoI complex [Co(PCPNMe‐iPr)(CO)2]. The CoIII hydride complex [Co(PCPNMe‐iPr)(CNtBu)2(H)]+ was obtained upon protonation of [Co(PCPNMe‐iPr)(CNtBu)2]. Three ways to cleave the agostic C?H bond are presented. First, owing to the acidity of the agostic proton, treatment with pyridine results in facile deprotonation (C?H bond cleavage) and reformation of [Co(PCPNMe‐iPr)(CO)2]. Second, C?H bond cleavage is achieved upon exposure of [Co(?3P,CH,P‐P(CH)PNMe‐iPr)(CO)2]+ to oxygen or TEMPO to yield the paramagnetic CoII PCP complex [Co(PCPNMe‐iPr)(CO)2]+. Finally, replacement of one CO ligand in [Co(?3P,CH,P‐P(CH)PNMe‐iPr)(CO)2]+ by CNtBu promotes the rapid oxidative addition of the agostic η2‐Caryl?H bond to give two isomeric hydride complexes of the type [Co(PCPNMe‐iPr)(CNtBu)(CO)(H)]+. 相似文献
12.
Alcohol‐Induced C−N Bond Cleavage of Cyclometalated N‐Heterocyclic Carbene Ligands with a Methylene‐Linked Pendant Imidazolium Ring 下载免费PDF全文
Dr. Wei Zhong Dr. Zhaofu Fei Dr. Rosario Scopelliti Prof. Dr. Paul J. Dyson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(34):12138-12144
Reaction of the pentamethylcyclopentadienyl rhodium iodide dimer [Cp*RhI2]2 with 1,1′‐diphenyl‐3,3′‐methylenediimidazolium diiodide in non‐alcohol solvents, in the presence of base, led to the formation of bis‐carbene complex [Cp*Rh(bis‐NHC)I]I (bis‐NHC=1,1′‐diphenyl‐4,4′‐methylenediimidazoline‐5,5′‐diylidene). In contrast, when employing alcohols as the solvent in the same reaction, cleavage of a methylene C?N bond is observed, affording ether‐functionalized (cyclometalated) carbene ligands coordinated to the metal center and the concomitant formation of complexes with a coordinated imidazole ligand. Studies employing other 1,1′‐diimidazolium salts indicate that the cyclometalation step is a prerequisite for the activation/scission of the C?N bond and, based on additional experimental data, a SN2 mechanism for the reaction is tentatively proposed. 相似文献
13.
Dr. Shaoguang Zhang Dr. Haixia Li Dr. Aaron M. Appel Prof. Michael B. Hall Dr. R. Morris Bullock 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(28):9493-9497
Unusual cleavage of P?C and C?H bonds of the P2N2 ligand, in heteroleptic [Ni(P2N2)(diphosphine)]2+ complexes under mild conditions, results in the formation of an iminium formyl nickelate featuring a C,P,P‐tridentate coordination mode. The structures of both the heteroleptic [Ni(P2N2)(diphosphine)]2+ complexes and the resulting iminium formyl nickelate have been characterized by NMR spectroscopy and single‐crystal X‐ray diffraction analysis. Density functional theory (DFT) calculations were employed to investigate the mechanism of the P?C/C?H bond cleavage, which involves C?H bond cleavage, hydride rotation, Ni?C/P?H bond formation, and P?C bond cleavage. 相似文献
14.
Utilising Sodium‐Mediated Ferration for Regioselective Functionalisation of Fluoroarenes via C−H and C−F Bond Activations 下载免费PDF全文
Dr. Lewis C. H. Maddock Dr. Tracy Nixon Dr. Alan R. Kennedy Dr. Michael R. Probert Prof. William Clegg Prof. Eva Hevia 《Angewandte Chemie (International ed. in English)》2018,57(1):187-191
Pairing iron bis(amide) Fe(HMDS)2 with Na(HMDS) to form new sodium ferrate base [(dioxane)0.5?NaFe(HMDS)3] ( 1 ) enables regioselective mono and di‐ferration (via direct Fe?H exchange) of a wide range of fluoroaromatic substrates under mild reaction conditions. Trapping of several ferrated intermediates has provided key insight into how synchronised Na/Fe cooperation operates in these transformations. Furthermore, using excess 1 at 80 °C switches on a remarkable cascade process inducing the collective twofold C?H/threefold C?F bond activations, where each C?H bond is transformed to a C?Fe bond whereas each C?F bond is transformed into a C?N bond. 相似文献
15.
Takanobu Saitou Yushu Jin Kotaro Isobe Takuya Suga Jun Takaya Nobuharu Iwasawa 《化学:亚洲杂志》2020,15(13):1941-1944
The Rh‐catalyzed direct carboxylation of alkenyl C?H bonds was achieved by using pyrazole as a removable directing group. In the presence of 5 mol% RhCl3 ? 3H2O, 6 mol% P(Mes)3, and 2 equiv. of AlMe2(OMe), the alkenyl C?H bond of various alkenylpyrazoles was directly carboxylated in good yields under CO2 atmosphere. Furthermore, several useful transformations of the pyrazole moiety of the product were achieved to afford synthetically useful carboxylic acid derivatives in good yields. 相似文献
16.
Lada Zámostná Prof. Dr. Thomas Braun Dr. Beatrice Braun 《Angewandte Chemie (International ed. in English)》2014,53(10):2745-2749
The degradation of SF6 and SF5 organyls by S? F and S? C bond‐activation reactions at [{Rh(μ‐H)(dippp)}2] under mild conditions is reported. Fluorido and thiolato species were identified as products or intermediates, and were characterized by X‐ray diffraction analysis and multinuclear NMR spectroscopy. An unprecedented cyclic process for the conversion of the potent greenhouse gas SF6 into H2S was developed. 相似文献
17.
Alberto Hernn‐Gmez Mnica Rodríguez Teodor Parella Miquel Costas 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(39):14042-14049
Combining an electrophilic iron complex [Fe(Fpda)(THF)]2 ( 3 ) [Fpda=N,N′‐bis(pentafluorophenyl)‐o‐phenylenediamide] with the pre‐activation of α‐alkyl‐substituted α‐diazoesters reagents by LiAl(ORF)4 [ORF=(OC(CF3)3] provides unprecedented access to selective iron‐catalyzed intramolecular functionalization of strong alkyl C(sp3)?H bonds. Reactions occur at 25 °C via α‐alkyl‐metallocarbene intermediates, and with activity/selectivity levels similar to those of rhodium carboxylate catalysts. Mechanistic investigations reveal a crucial role of the lithium cation in the rate‐determining formation of the electrophilic iron‐carbene intermediate, which then proceeds by concerted insertion into the C?H bond. 相似文献
18.
Robin Guthardt Jan Oetzel Julia I. Schweizer Clemens Bruhn Robert Langer Martin Maurer Jan Vícha Pavletta Shestakova Max C. Holthausen Ulrich Siemeling 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(5):1401-1405
The N‐heterocyclic plumbylene [Fe{(η5‐C5H4)NSiMe3}2Pb:] is in equilibrium with an unprecedented dimer in solution, whose formation involves the cleavage of a strong C?H bond and concomitant formation of a Pb?C and an N?H bond. According to a mechanistic DFT assessment, dimer formation does not involve direct PbII insertion into a cyclopentadienyl C?H bond, but is best described as an electrophilic substitution. The bulkier plumbylene [Fe{(η5‐C5H4)NSitBuMe2}2Pb:] shows no dimerization, but compensates its electrophilicity by the formation of an intramolecular Fe?Pb bond. 相似文献
19.
《化学:亚洲杂志》2017,12(2):239-247
Five bis(quinolylmethyl)‐(1H ‐indolylmethyl)amine (BQIA) compounds, that is, {(quinol‐8‐yl‐CH2)2NCH2(3‐Br‐1H ‐indol‐2‐yl)} ( L1H ) and {[(8‐R3‐quinol‐2‐yl)CH2]2NCH(R2)[3‐R1‐1H ‐indol‐2‐yl]} ( L2–5H ) ( L2H : R1=Br, R2=H, R3=H; L3H : R1=Br, R2=H, R3=i Pr; L4H : R1=H, R2=CH3, R3=i Pr; L5H : R1=H, R2=n Bu, R3=i Pr) were synthesized and used to prepare calcium complexes. The reactions of L1–5H with silylamido calcium precursors (Ca[N(SiMe2R)2]2(THF)2, R=Me or H) at room temperature gave heteroleptic products ( L1, 2 )CaN(SiMe3)2 ( 1 , 2 ), ( L3, 4 )CaN(SiHMe2)2 ( 3 a , 4 a ) and homoleptic complexes ( L3, 5 )2Ca ( D3 , D5 ). NMR and X‐ray analyses proved that these calcium complexes were stabilized through Ca⋅⋅⋅C−Si, Ca⋅⋅⋅H−Si or Ca⋅⋅⋅H−C agostic interactions. Unexpectedly, calcium complexes (( L3–5 )CaN(SiMe3)2) bearing more sterically encumbered ligands of the same type were extremely unstable and underwent C−N bond cleavage processes as a consequence of intramolecular C−H bond activation, leading to the exclusive formation of (E )‐1,2‐bis(8‐isopropylquinol‐2‐yl)ethane. 相似文献
20.
Sathiyamoorthy Murugesan Berthold Stger Ernst Pittenauer Günter Allmaier Luis F. Veiros Karl Kirchner 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(9):3097-3100
The synthesis and reactivity of a CoI pincer complex [Co(ϰ3P,CH,P‐P(CH)PNMe‐iPr)(CO)2]+ featuring an η2‐ Caryl−H agostic bond is described. This complex was obtained by protonation of the CoI complex [Co(PCPNMe‐iPr)(CO)2]. The CoIII hydride complex [Co(PCPNMe‐iPr)(CNtBu)2(H)]+ was obtained upon protonation of [Co(PCPNMe‐iPr)(CNtBu)2]. Three ways to cleave the agostic C−H bond are presented. First, owing to the acidity of the agostic proton, treatment with pyridine results in facile deprotonation (C−H bond cleavage) and reformation of [Co(PCPNMe‐iPr)(CO)2]. Second, C−H bond cleavage is achieved upon exposure of [Co(ϰ3P,CH,P‐P(CH)PNMe‐iPr)(CO)2]+ to oxygen or TEMPO to yield the paramagnetic CoII PCP complex [Co(PCPNMe‐iPr)(CO)2]+. Finally, replacement of one CO ligand in [Co(ϰ3P,CH,P‐P(CH)PNMe‐iPr)(CO)2]+ by CNtBu promotes the rapid oxidative addition of the agostic η2‐Caryl−H bond to give two isomeric hydride complexes of the type [Co(PCPNMe‐iPr)(CNtBu)(CO)(H)]+. 相似文献