Application of 13C NMR to the determination of metal—carbon σ bond formation in cyclometallation reactions with nitrogen donor ligands

Garber, A. R.; Garrou, Philip E.; Hartwell, George E.; Smas, M. J.; Wilkinson, James A.; Todd, Lee J.

doi:10.1016/s0022-328x(00)89614-x

Cited by 40 publications

(7 citation statements)

References 16 publications

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“…JH NMR is also complicated by the presence of complex patterns when metalation has occurred either on a phenyl ring or an alkyl group in the presence of unmetalated ligands.4'5 13C NMR has also been examined, 6 but, on all but the simplest systems, this method is complicated by overlapping resonances and the inherent low intensity of the metalated carbon. Analyses of these spectra become research projects in their own right.…”

Section: Previous Methods Of Determining Chelation In Phosphine Compl...mentioning

confidence: 99%

“…Note the AR results are within 1 ppm of each other. If comparisons are made where the trans ligands are not the same, errors of [1][2][3][4][5][6][7][8][9][10] ppm and more are possible depending on the electronic differences (trans effects) of the ligands in question. This is exemplified in 7 where an internal comparison of 6Px vs. 5Pa would Ph3P 9, 6 P -6.0 In contrast, deshielding due to phosphorus incorporation into 5-membered ring systems is observed when one compares 1-methylphosphole (<5P -8.7) to ethyldivinylphosphine (5P -20.8).…”

Section: Previous Methods Of Determining Chelation In Phosphine Compl...mentioning

confidence: 99%

“…29 The 31P NMR spectrum of complex 2816 can be compared to that of Mo2(CO)6(dmpe)3 which has dP resonances at -2.5 and +24.4 for bridging and chelating co 28, 6p . + 42.2 6 Pg +23.6 phosphorus atoms, respectively, resulting in a AR contribution of +26.1 to the value of 5P?. King et al30 recognized the additive nature of AR in complexes of type 29 (M = Cr, Mo, W) where etp functions as a 29 tridentate ligand.…”

Section: Previous Methods Of Determining Chelation In Phosphine Compl...mentioning

confidence: 99%

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.DELTA.R-ring contributions to phosphorus-31 NMR parameters of transition-metal-phosphorus chelate complexes

Garrou¹

1981

Chem. Rev.

1,005

505

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Section: Previous Methods Of Determining Chelation In Phosphine Compl...mentioning

confidence: 99%

Section: Previous Methods Of Determining Chelation In Phosphine Compl...mentioning

confidence: 99%

Section: Previous Methods Of Determining Chelation In Phosphine Compl...mentioning

confidence: 99%

See 1 more Smart Citation

.DELTA.R-ring contributions to phosphorus-31 NMR parameters of transition-metal-phosphorus chelate complexes

Garrou¹

1981

Chem. Rev.

1,005

505

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“…There are only a few papers in the literature about the influence of the metal on carbon chemical shifts in orthopalladation reactions. When a Pd᎐C (aliphatic) bond is formed a small deshielding (∆δ ≈ 5 ppm) 14 is observed, which becomes larger in the case of a Pd᎐C (aromatic) bond (∆δ ≈ 18 ppm), 14 probably due to Pd᎐C back bonding. This effect is substantially larger for azobenzene and benzylideneamine complexes, where ∆δ is higher than 30 ppm.…”

Section: Characterizationmentioning

confidence: 99%

Optically active cyclopalladated derivatives of arylimines. Crystal structures of (+)-[{Pd[p-MeOC6H3CHNCH2-(1S,2R,5S)CHCH2CH2CHC(Me)2CHCH2](μ-X)}2] (X = Cl or Br), (+)-[Pd{p-MeOC6H3CHNCH2-(1S,2R,5S )-CHCH2CH2CHC(Me)2CHCH2}Cl(PPh3)] and (+)-[{Pd[p-MeOC6H3CHNCH2-(1S,2R,5S)-CHCH2CH2CHC(Me)2CHCH2]Cl}2{Fe(δ5-C5H4PPh2)2}]

Zhao¹,

Wang²,

Mak³

1998

J. Chem. Soc., Dalton Trans.

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“…Cyclopalladated complexes (41-60) can be generated from other nitrogendonor ligands such as benzylideneamines, ferrocenylmethylamines, pyridine, quinoline, benzoquinoline, and amide, with different palladation sources. [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45]…”

Section: Other Nitrogen-donor Complexesmentioning

confidence: 99%

Design and synthesis of chiral organopalladium-amine complexes

Yap¹

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Bn benzyl Bu butyl br broad c concentration for optical rotation analysis calcd calculated conc. concentrated CDCl3 chloroform-d1 CD2Cl2 dichloromethane-d2 CHCl3 chloroform CH3CN acetonitrile Claisen's alkali a strong base prepared by 8.81 g KOH dissolved in 6 ml of XI Summary This thesis describes the design and synthesis of chiral organopalladium-amine complexes and their applications in stoichiometric asymmetric synthesis. A brief introduction on the organopalladium-amine complexes, the research development and the objective of this project were presented in Chapter 1. In Chapter 2, a functionalized amine, 1-(2,5-di-tert-butylphenyl)-N,Ndimethylethanamine was designed and synthesized, but the ortho-palladation reaction did not give the desired palladacycle. An unexpected C−N bond cleavage was observed and gave two C−N bond cleavage complexes. The mechanistic studies on the formation of C−N bond cleavage complex was carried out, but no substantial conclusion can be made yet. The initial step is likely β-hydride elimination and it is a base promoted reaction. Chapter 3 describes the synthesis of slightly less bulky amine ligand, 1-(2,5-diiso-propylphenyl)-N,N-dimethylethanamine from p-di-iso-propylbenzene. By optimizing the reaction conditions including replacement of some of the reagents, it resulted in increased of the overall yield of the amine ligand. The ortho-palladation reaction gave the desired palladacycle and C−N bond cleavage complex by varying the palladating agent used. The racemic dimeric complex was resolved by separation of the (S)-prolinate diastereomeric derivatives via column chromatography. The efficiency of the palladacycle was assessed via the asymmetric intramolecular endocycloaddition reaction and a better stereoselectivity was obtained. In chapter 4 describes the synthesis of an electron-withdrawing group functionalized benzyl palladacycle to investigate the electronic effect of the palladacycle in asymmetric Diel-Alder reaction. The amine ligand, 1-(2,5dichlorophenyl)-N,N-dimethylethanamine was synthesized via three step synthetic XII route with high overall yield and ortho-palladation with Pd(OAc)2 to give the acetatebridged dimeric palladacycle. The racemic dimer was resolved with optically active sodium prolinate and by treatment of the corresponding diastereomer with aqueous 1M HCl produced the chiral chloro-bridged dimer. The efficiency of the palladacycle was examined via Diels-Alder reaction between DMPP-coordinated complex and ethyl vinyl ketone, however poor stereoselectivity was observed. The chiral dimeric complex was converted to the cationic complex and used in asymmetric hydrophosphination reaction between diphenylphosphine and DMAD to give one diastereomeric product.

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Application of 13C NMR to the determination of metal—carbon σ bond formation in cyclometallation reactions with nitrogen donor ligands

Cited by 40 publications

References 16 publications

.DELTA.R-ring contributions to phosphorus-31 NMR parameters of transition-metal-phosphorus chelate complexes

.DELTA.R-ring contributions to phosphorus-31 NMR parameters of transition-metal-phosphorus chelate complexes

Design and synthesis of chiral organopalladium-amine complexes

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