Metathesis of Olefin-Substituted Pyridines: The Metalated NCN-Pincer Complex in a Dual Role as Protecting Group and Scaffold Part of this work was presented at the 14th International Symposium on Olefin Metathesis, Boston, August 2001

Dijkstra, Harm P.; Chuchuryukin, Aleksey V.; Suijkerbuijk, Bart M. J. M.; Klink, Gerard P. M. van; Mills, Allison M.; Spek, Anthony L.; Koten, Gerard van

doi:10.1002/1615-4169(200208)344:6/7<771::aid-adsc771>3.0.co;2-c

Cited by 34 publications

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“…C,19 F, and11 B NMR spectra, mass spectra, IR spectra, elemental analysis report for new complexes, h i b i t e d .…”

mentioning

confidence: 78%

“…9 However, the molecular structure for the complex was reported 12 years after the first report by the same group along with new cationic complexes, dinuclear chloride bridging palladium(II) complexes 10 The same group has reported cationic palladium(II) complexes with diolefin-substituted pyridines at the ancillary sites [9 (Chart 3)], and their utility has been investigated for olefin metathesis. 11 Similar para-functionalized cationic palladium(II) complexes, para-substituted [{2,6-(Me 2 NCH 2 ) 2 C 6 H 2 }Pd-(OH 2 )] + [BF 4 ] − , have been used for Michael reaction between methyl vinyl ketone and ethyl α-cyanoacetate. 12 A unique type of chiral cationic NCN palladium pincer complex with κ 5 -N,C,N,O,O coordination around the palladium center is reported [10 (Chart 3)] with R N R N S C S C diastereospecificity containing diphenylhydroxymethyl pyrrolidinyl moieties as chiral auxiliaries, and these complexes were further used as catalysts for the aldol condensation reaction between α-methyl isocyanoacetate and aromatic aldehydes to yield cis-oxazolines with 42% ee.…”

Section: ■ Introductionmentioning

confidence: 99%

“…However, the molecular structure for the complex was reported 12 years after the first report by the same group along with new cationic complexes, dinuclear chloride bridging palladium(II) complexes [{(2,6-(Me 2 NCH 2 ) 2 C 6 H 3 )Pd} 2 (μ-Cl)] + [X] − , where X – = [BF 4 ] − , [B{C 6 H 4 (SiMe 3 )-4} 4 ] − , or [B{C 6 H 4 (SiMe 2 CH 2 CH 2 C 6 F 13 )-4} 4 ] − [ 8 (Chart )] . The same group has reported cationic palladium(II) complexes with diolefin-substituted pyridines at the ancillary sites [ 9 (Chart )], and their utility has been investigated for olefin metathesis . Similar para -functionalized cationic palladium(II) complexes, para -substituted [{2,6-(Me 2 NCH 2 ) 2 C 6 H 2 }Pd(OH 2 )] + [BF 4 ] − , have been used for Michael reaction between methyl vinyl ketone and ethyl α-cyanoacetate .…”

Section: Introductionmentioning

confidence: 99%

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Cationic NCN Palladium(II) Pincer Complexes of 5-tert-Butyl-1,3-bis(N-substituted benzimidazol-2′-yl)benzenes: Synthesis, Structure, and Pd···Pd Metallophilic Interaction

2017

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The NCN palladium(II) pincer complex [Benzoyl(N∧C∧N)PdBr] (16) was synthesized by the oxidative addition of Benzoyl(N∧C∧N)Br to Pd(dba)2 in 85% yield [(N∧C∧N) = 5-tert-butyl-1,3-bis(N-substituted benzimidazol-2′-yl)phenyl)]. Then treatment of complex 16 with KI yielded the iodopalladium complex [Benzoyl(N∧C∧N)PdI] (17) in 92% yield. Furthermore, a series of cationic palladium(II) complexes, including [Benzoyl(N∧C∧N)Pd(MeCN)]+[BF4]− (18), [Benzoyl(N∧C∧N)Pd(MeCN)]+[SbF6]− (19), and [Benzoyl(N∧C∧N)Pd(OTf)] (20), were prepared in 68–79% yields by the reaction of the neutral palladium(II) complex (16) with AgBF4, AgSbF6, and AgOTf, respectively. Similarly, previously synthesized Tosyl(N∧C∧N)PdBr [5-tert-butyl-1,3-bis(N-tosylbenzimidazol-2′-yl)phenyl]palladium bromide (5b) was treated with AgSO3CF3 and AgSbF6 to afford cationic palladium(II) complexes [Tosyl(N∧C∧N)Pd(OTf)] (21) and [Tosyl(N∧C∧N)Pd(MeCN)]+[SbF6]− (22) in 41 and 61% yields, respectively. 5-tert-Butyl-1,3-bis[{(N-tosylbenzimidazol-2′-yl)phenyl}palladium(II)] triflate (21) exhibited an unsupported metallophillic Pd···Pd interaction [3.166(8) Å] that is corroborated by X-ray crystallographic studies. Compared to other cationic palladium complexes, complex 21 was found to be less stable. In Atoms in Molecule (AIM) analysis, the bond critical point (ρ) between Pd and Pd atoms is 0.000865 au, supporting the presence of metallophillic interaction in complex 21. The bond strength of the Pd···Pd bond was also measured by density functional theory calculations that indicated that the calculated bond order was approximately one-fourth of the normal covalent Pd–Pd bond (natural atomic orbital bond order method). All eight complexes, two neutral and six cationic, were characterized by common spectroscopic techniques, and six complexes were corroborated by X-ray diffraction studies.

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“…C,19 F, and11 B NMR spectra, mass spectra, IR spectra, elemental analysis report for new complexes, h i b i t e d .…”

mentioning

confidence: 78%

Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cationic NCN Palladium(II) Pincer Complexes of 5-tert-Butyl-1,3-bis(N-substituted benzimidazol-2′-yl)benzenes: Synthesis, Structure, and Pd···Pd Metallophilic Interaction

2017

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“…Indeed, the 5-fold RCM reaction of 1 proceeded as we expected; however, the major product from the reaction was not 2 but the isomeric single-bridged bis(tetrahydrofluorenyl)Fe(II) species 3 (Scheme ). It should be pointed out that the multifold RCM reactions have been utilized for assembling/modulating various transition-metal complexes − and topologically unique organic compounds. − …”

Section: Introductionmentioning

confidence: 99%

Inter- versus Intraannular Ring-Closing Metathesis of Polyallylferrocenes: Five-Fold RCM within a Single Molecule

Ogasawara

Arae

et al. 2013

Organometallics

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Treatment of decaallylferrocene (1) with the Grubbs-II catalyst in refluxing dichloromethane has promoted the 5-fold ringclosing metathesis in 1 to afford single-bridged bis(1,4,5,8tetrahydrofluorenyl)iron(II) species 3 in excellent yield. The preferential formation of 3 over quintuply bridged "superferrocenophane" 2 was explained as the intraannular RCM process being preferred over the interannular one in the reactions of polyallylferrocenes.

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“…Accordingly, binding of pyridine ligands provides a special molecular arrangement having the planes of the tris(phenylene)benzene core and the pyridine ligands coplanar. It turns out that of the combinations ECE pincer ligand/metal/pyridine (E: N, S; metal: palladium, platinum) the NCN pincer platinum pyridine complexes are the kinetically most stable ones 9. Moreover, the NCN‐Pt complexes are the least active catalysts for the isomerization of α‐olefins (see below).…”

Section: Methodsmentioning

confidence: 99%

Macrocycle Synthesis by Olefin Metathesis on a Nanosized, Shape‐Persistent Tricationic Platinum Template

et al. 2003

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Macrocyclic compounds are widely used as preorganized host molecules for the selective binding of specific guests. [1] Commonly, these guests are monometallic cations or small polar molecules, such as urea. An alternative possibility is to assemble a given set of molecules around a metal center [2] or molecular pattern [3,4] and then couple the molecules to one host±guest complex. In this reaction sequence the metal center or molecular pattern functions as template.[5] In a number of recent reports the latter strategy has been used for the synthesis of catenanes and knots, [6] and of molecular wires imbedded in an alkane double helix. [7] In these reactions, host and guest often become irreversibly integrated in an assembly with novel molecular properties.In a recent study, we prepared a series of shape-persistent multimetallic compounds which can be easily converted into the corresponding multicationic species.[8] The cationic sites in the trication of 1 (see Scheme 1) used in the present study are fixed in a two-dimensional space and are at the corners of a triangle with edges of 1.75 nm.[8b] The NCN pincer platinum cations bind new ligands exclusively trans to C ipso along the pseudo C 2 axis of the molecule (C 4 -C ipso -Pt). Accordingly, binding of pyridine ligands provides a special molecular arrangement having the planes of the tris(phenylene)benzene core and the pyridine ligands coplanar. It turns out that of the combinations ECE pincer ligand/metal/pyridine (E: N, S; metal: palladium, platinum) the NCN pincer platinum pyridine complexes are the kinetically most stable ones. [9] Moreover, the NCN-Pt complexes are the least active catalysts for the isomerization of a-olefins (see below). This makes the trication of 1 an ideal template for interconnecting the pyridine rings at the ortho or meta positions thereby forming a large tris(pyridyl) macrocyclic compound around the trication.Here we report the selective linking of 2,6-bis(dec-9-enyloxy)pyridine substituents by alkene metathesis to form a 69-membered tris(pyridyl) macrocycle. Its detachment occurs by addition of nucleophiles, for example, Cl À . The trisolefinic macrocycle could be hydrogenated and subsequently recoordinated to the tricationic template. This sequence (Scheme 1) provides a new approach to the selective synthesis of largering macrocyclic hosts which have as the only preorganization a precise atom connectivity pattern.2,6-Bisolefin-substituted pyridines 2 a,b were prepared from 9-decen-1-ol and 2,6-dibromopyridine or 2,6-bis(chloromethyl)pyridine, respectively. The template precursor 1 (1 mmol) was reacted in CH 2 Cl 2 with three equivalents of either 2 a or 2 b in the presence of suspended AgBF 4 to give the tricationic compounds 3 a or 3 b, respectively, in quantitative yields. A prolonged reaction time (30 min to 16 h) is necessary because of the poor solubility of AgBF 4 in CH 2 Cl 2 . The compounds 3 undergo alkene metathesis in the presence of the first-generation Grubbs catalyst, [Cl 2 (Cy 3 P) 2 Ru¼ CHPh] (5 mol % per pyridine ...

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Metathesis of Olefin-Substituted Pyridines: The Metalated NCN-Pincer Complex in a Dual Role as Protecting Group and Scaffold Part of this work was presented at the 14th International Symposium on Olefin Metathesis, Boston, August 2001

Cited by 34 publications

References 0 publications

Cationic NCN Palladium(II) Pincer Complexes of 5-tert-Butyl-1,3-bis(N-substituted benzimidazol-2′-yl)benzenes: Synthesis, Structure, and Pd···Pd Metallophilic Interaction

Cationic NCN Palladium(II) Pincer Complexes of 5-tert-Butyl-1,3-bis(N-substituted benzimidazol-2′-yl)benzenes: Synthesis, Structure, and Pd···Pd Metallophilic Interaction

Inter- versus Intraannular Ring-Closing Metathesis of Polyallylferrocenes: Five-Fold RCM within a Single Molecule

Macrocycle Synthesis by Olefin Metathesis on a Nanosized, Shape‐Persistent Tricationic Platinum Template

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