Synthesis and Double C-H Activation of Palladium(II) Complexes with the Cationic Ligand [To3PCH2(Py-2)]+ (To = C6H4Me-4, Py = Pyridine). Some Evidence of the Formation of a Palladium(IV) Complex. Crystal and Molecular Structures of trans-[PdCl2{Py{CH2PTo3}-2}2](ClO4)2.cntdot.4Cl2CH2, [PdCl{.mu.2-.kappa.3-C6H3{PTo2CH(Py-2')-2}Me-4}]2.cntdot.2Cl2CH2, and cis-[PdI2{.kappa.2-C6H3{PTo2CHCl(Py-2')-2}Me-4}].cntdot.Cl2CH2

Vicente, José; Chicote, Mariá‐Teresa; Lagunas, M. Cristina; Jones, Peter G.; Bembenek, Eberhard

doi:10.1021/om00016a029

Cited by 53 publications

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“…Cyclopalladation reactions involving a C(sp 2 )−H activation are by far the best known, while those involving a C(sp 3 )−H bond are a minority. ,− Those involving a prochiral C(sp 3 )−H bond are very rare. ,, In this paper, we report the synthesis of a family of cyclopalladated complexes with a chiral C(sp 3 ) atom bonded to Pd.…”

Section: Introductionmentioning

confidence: 99%

“…We are interested in the coordination properties of ligands with several different donor atoms (multidonor ligands), particularly 2-substituted pyridine derivatives. Thus, we have synthesized a variety of mono- and polynuclear silver(I), gold(I), − and Pd(II) deriva-tives. , The polynuclear complexes of d 10 metal ions offered us the possibility of studying metal−metal interactions, which are the subject of considerable interest, ,− whereas in the case of palladium, unusual dicationic [PdCl 2 L 2 ] 2+ and neutral [PdCl 3 L] complexes [where L is the phosphonium cation [To 3 PCH 2 (py-2)] + ] were obtained, which underwent a facile double C−H activation process . Recently we have studied the reactivity of 2-(R−carbonylmethylenthio)pyridine [py{SCH 2 C(O)R}-2, R = Ph, Me, OMe] toward Ag(I), Au(I), and Au(III) and discussed the differing abilities of these metal centers to coordinate to the various donor atoms of these ligands, as well as the capacity of Au(III) to metalate the methylene carbon atom. , In this paper, we report the first complexes of Pd(II) derived from these multidonor ligands, which, as far as we are aware, are the first bearing a sulfur atom between both coordinate atoms of a palladacycle.…”

Section: Introductionmentioning

confidence: 99%

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Multidonor Ligands. 3. Cyclopalladation of py{SCH₂C(O)R}-2 (py-2 = 2-pyridyl, R = Ph, Me, OMe) through a C(sp³)−H Bond Activation

et al. 1999

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[PdCl2(NCPh)2] reacts with R−carbonylmethylenethiopyridines [py{SCH2C(O)R}-2] to give, depending on the substituent R and the reaction conditions, or the coordination complexes [Pd{py{SCH2C(O)R}-2}2Cl2] (R = Ph, Me, OMe). The latter can be doubly deprotonated by a base (Na2CO3 or NaH) to give dicyclometalated complexes These transmetalate one ligand to [PdCl2(NCPh)2] to give which in turn reacts with (Me4N)Cl or with monodentate ligands L or with MeCN in the presence of AgClO4 to give anionic neutral [R = Ph, L = PPh3, py{SCH2C(O)Ph}-2, tBuNC, NH2CH(Me)Ph, pyridine (py), tetrahydrothiophene (tht); R = Me, L = PPh3, py, tht], or cationic (R = Ph, Me, OMe) complexes, respectively. The latter react with PPh3 or with bidentate ligands to give complexes or [L = PPh3, L2 = N,N,N‘,N‘-tetramethylethylenediamine (tmeda) or 2,2‘-bipyridine (bipy)]. The crystal structures of and have been determined.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Multidonor Ligands. 3. Cyclopalladation of py{SCH₂C(O)R}-2 (py-2 = 2-pyridyl, R = Ph, Me, OMe) through a C(sp³)−H Bond Activation

et al. 1999

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“…This C−H activation can be induced either thermally (refluxing NCMe) or by addition of auxiliary ligands under very mild conditions (CH 2 Cl 2 , room temperature). Due to the intrisic interest of reactions involving C−H activation and also due to the fact that the number of C,C-orthometalated complexes is relatively scarce − compared with other C,X-cyclometalated (X = heteroatom) derivatives, , we have performed a systematic study of this particular C−H activation in bis(ylide) complexes. Even though the orthometalation of ylides has been known for several years, − ,, we are not aware of a mechanistic proposal for this reaction, nor of a study of the influence of different parameters on this process.…”

Section: Introductionmentioning

confidence: 99%

“…Due to the intrisic interest of reactions involving C−H activation and also due to the fact that the number of C,C-orthometalated complexes is relatively scarce − compared with other C,X-cyclometalated (X = heteroatom) derivatives, , we have performed a systematic study of this particular C−H activation in bis(ylide) complexes. Even though the orthometalation of ylides has been known for several years, − ,, we are not aware of a mechanistic proposal for this reaction, nor of a study of the influence of different parameters on this process. To shed light on these questions, we report here our first results with this previously unexplored chemistry.…”

Section: Introductionmentioning

confidence: 99%

Ligand-Induced and Thermally-Induced Orthometalation of the Bis(ylide) Ligand [Ph₃PC(H)]₂CO. Generation of the C,C-Chelating Group C₆H₄-2-PPh₂C((H)COCH₂PPh₃

et al. 1998

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The dinuclear complex [Pd(μ-Cl){[C(H)PPh3]2CO}]2(ClO4)2 (2c) undergoes thermal rearrangement in refluxing NCMe, giving the dinuclear orthometalated derivative [Pd(μ-Cl)(C6H4-2-PPh2C(H)COCH2PPh3)]2(ClO4)2 (4c) as a mixture of two diastereoisomers (RR/SS and RS/SR). The orthometalation proceeds through an electrophilic substitution pathway, and the formation of the C,C-chelating ligand (C 6H4-2-PPh2 C(H)COCH2PPh3) results from an intramolecular acid−base reaction in which the proton generated in the orthometalation reaction is captured by an ylide group. A decrease in the cone angle of the phosphonium group dramatically reduces the conversion of the bis(ylide) ligand into the orthometalated ligand. The orthometalation reaction can also be induced by ligand addition to the dimer [Pd(μ-Cl){[C(H)PPh3]2CO}]2(ClO4)2 (2c) under very mild conditions. For instance, complex 2c reacts with PPh3 or PPhMe2 in CH2Cl2 at room temperature to give [PdCl(C6H4-2-PPh2C(H)COCH2PPh3)(PR3)](ClO4) (PR3 = PPh3 8, PPhMe2 9). Less sterically hindered ligands such as pyridine or 3,5-lutidine react with 2c to give in a first step the bis(ylide) complexes [PdCl{[C(H)PPh3]2CO}(L)](ClO4) (L = py; 3,5-lut), which are transformed into the corresponding orthometalated derivatives [PdCl(C6H4-2-PPh2C(H)COCH2PPh3)(L)](ClO4) (L = py 6, 3,5-lut 7) by thermal treatment in refluxing NCMe. This different behavior is explained on the grounds of the different steric requirements of the incoming ligand (phosphine/pyridine). Similar behavior has been observed for the complex [Pd{[C(H)PPh3]2CO}(NCMe)2](ClO4)2 (3c). 3c reacts with py or dppm giving [Pd{[C(H)PPh3]2CO}(L)2](ClO4)2 (L = py 10, L2 = dppm 11), which is transformed into [Pd(C6H4-2-PPh2C(H)COCH2PPh3)(L2)](ClO4) (L = py 12, L2 = dppm 13a + dppm-O 13b) by refluxing in NCMe. However, complex 3c reacts with PPh3, dppe, or phen in CH2Cl2 at room temperature giving [Pd(C6H4-2-PPh2C(H)COCH2PPh3)(L2)](ClO4) (L2 = PPh3, NCMe 14, dppe 15, phen 16). Complex 3c is not transformed into its corresponding orthometalated derivative [Pd(C6H4-2-PPh2C(H)COCH2PPh3)(NCMe)2](ClO4)2 (17) by refluxing in NCMe, but 17 can be obtained by treatment of 4c with TlClO4 in NCMe. The orthometalation reaction of the bis(ylide) ligand can even occur spontaneously. The acetate-bridged dimer [Pd(μ-OOCCH3){[C(H)PPh3]2CO}]2(ClO4)2 (18) transforms spontaneously at room temperature into the mixed orthometalated bis(ylide)complex [(C6H4-2-PPh2C(H)COCH2PPh3)Pd(μ-OOCCH3)2Pd{[C(H)PPh3]2CO}](ClO4)2 (19). The crystal structure of [Pd(C6H4-2-PPh2C(H)COCH2PPh3)(PPh3)(NCMe)](ClO4)2 (14) has been determined and reveals the presence of an orthometalated C6H4-2-PPh2 unit, a C-linked ylide Pd−C(H), and a phosphonium fragment CH2PPh3. The phosphine group is coordinated cis to the orthometalated carbon atom.

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“…Complex 383 then underwent subsequent carbon–chlorine reductive elimination to yield chlorinated palladacycle 384 (Scheme ). This represents an interesting example of a C(sp 3 )–halogen reductive elimination occurring in the presence of a Pd–C(sp 2 ) bond.…”

Section: Synthesis Of Alkyl Halidesmentioning

confidence: 99%

Modern Transition-Metal-Catalyzed Carbon–Halogen Bond Formation

2016

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The high utility of halogenated organic compounds has prompted the development of a vast number of transformations which install the carbon-halogen motif. Traditional routes to these building blocks have commonly involved multiple steps, harsh reaction conditions, and the use of stoichiometric and/or toxic reagents. In this regard, using transition metals to catalyze the synthesis of organohalides has become a mature field in itself, and applying these technologies has allowed for a decrease in the production of waste, higher levels of regio- and stereoselectivity, and the ability to produce enantioenriched target compounds. Furthermore, transition metals offer the distinct advantage of possessing a diverse spectrum of mechanistic possibilities which translate to the capability to apply new substrate classes and afford novel and difficult-to-access structures. This Review provides comprehensive coverage of modern transition metal-catalyzed syntheses of organohalides via a diverse array of mechanisms. Attention is given to the seminal stoichiometric organometallic studies which led to the corresponding catalytic processes being realized. By breaking this field down into the synthesis of aryl, vinyl, and alkyl halides, it becomes clear which methods have surfaced as most favored for each individual class. In general, a pronounced shift toward the use of C-H bonds as key functional groups, in addition to methods which proceed by catalytic, radical-based mechanisms has occurred. Although always evolving, this field appears to be heading in the direction of using starting materials with a significantly lower degree of prefunctionalization in addition to less expensive and abundant metal catalysts.

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Cited by 53 publications

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Multidonor Ligands. 3. Cyclopalladation of py{SCH₂C(O)R}-2 (py-2 = 2-pyridyl, R = Ph, Me, OMe) through a C(sp³)−H Bond Activation

Multidonor Ligands. 3. Cyclopalladation of py{SCH₂C(O)R}-2 (py-2 = 2-pyridyl, R = Ph, Me, OMe) through a C(sp³)−H Bond Activation

Ligand-Induced and Thermally-Induced Orthometalation of the Bis(ylide) Ligand [Ph₃PC(H)]₂CO. Generation of the C,C-Chelating Group C₆H₄-2-PPh₂C((H)COCH₂PPh₃

Modern Transition-Metal-Catalyzed Carbon–Halogen Bond Formation

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Cited by 53 publications

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Multidonor Ligands. 3. Cyclopalladation of py{SCH2C(O)R}-2 (py-2 = 2-pyridyl, R = Ph, Me, OMe) through a C(sp3)−H Bond Activation

Multidonor Ligands. 3. Cyclopalladation of py{SCH2C(O)R}-2 (py-2 = 2-pyridyl, R = Ph, Me, OMe) through a C(sp3)−H Bond Activation

Ligand-Induced and Thermally-Induced Orthometalation of the Bis(ylide) Ligand [Ph3PC(H)]2CO. Generation of the C,C-Chelating Group C6H4-2-PPh2C((H)COCH2PPh3

Modern Transition-Metal-Catalyzed Carbon–Halogen Bond Formation

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Multidonor Ligands. 3. Cyclopalladation of py{SCH₂C(O)R}-2 (py-2 = 2-pyridyl, R = Ph, Me, OMe) through a C(sp³)−H Bond Activation

Multidonor Ligands. 3. Cyclopalladation of py{SCH₂C(O)R}-2 (py-2 = 2-pyridyl, R = Ph, Me, OMe) through a C(sp³)−H Bond Activation

Ligand-Induced and Thermally-Induced Orthometalation of the Bis(ylide) Ligand [Ph₃PC(H)]₂CO. Generation of the C,C-Chelating Group C₆H₄-2-PPh₂C((H)COCH₂PPh₃