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Volumn 126, Issue 20, 2004, Pages 6332-6346

Mechanism of palladium-catalyzed diene cyclization/hydrosilylation: Direct observation of intramolecular carbometalation

Author keywords

[No Author keywords available]

Indexed keywords

ADDITION REACTIONS; CATALYSIS; CATALYSTS; CHEMICAL ANALYSIS; COMPLEXATION;

EID: 2442677765     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja049806f     Document Type: Article
Times cited : (41)

References (99)
  • 27
    • 2442693563 scopus 로고    scopus 로고
    • note
    • (a) These secondary transformations include the oxidation of organosilanes10b and organoboranes and the cross-coupling of alkenylsilanes,10c alkenylstannanes,10d and organoboranes.10e
  • 40
    • 2442647188 scopus 로고    scopus 로고
    • note
    • 1H NMR.
  • 43
    • 2442707241 scopus 로고    scopus 로고
    • note
    • We cannot rule out a structure for 5 in which the α -(triethylsilyl)methyl group and the terminus of the complexed olefin have a cis relationship. However, if this were the case, cis to trans isomerization must precede conversion of 5 to 6, and this isomerization must be fast relative to the conversion of 5 to 6 as the rate of conversion of 5 to 6 was independent of [NCAr].
  • 48
    • 2442703588 scopus 로고    scopus 로고
    • note
    • t = 0.0196 M (95% conversion).27b
  • 52
    • 2442703590 scopus 로고    scopus 로고
    • note
    • The principle source of error in our kinetic measurements was determination of catalyst concentration, which stemmed from the difficulty in accurately weighing 2b into the NMR tube. Efforts to improve the accuracy of these measurements by employing stock solutions of 2b were unsuccessful due to the short lifetime of 2b in solution at ambient temperature.
  • 68
    • 0022047210 scopus 로고
    • and references therein
    • Lehmkuhl, H. Pure Appl. Chem. 1986, 58, 495 and references therein.
    • (1986) Pure Appl. Chem. , vol.58 , pp. 495
    • Lehmkuhl, H.1
  • 77
    • 2442648488 scopus 로고    scopus 로고
    • note
    • 2 group in the transition state [for the β-migratory insertion of 13], especially the former, make the transition state potentially quite atypical."46b
  • 78
    • 2442657285 scopus 로고    scopus 로고
    • note
    • -1 relative to the corresponding acyclic alkyl complex.
  • 87
    • 2442714589 scopus 로고    scopus 로고
    • note
    • 2 was consistent with orientation of the olefin in or near the coordination plane, and for this reason, no significant olefin rotation or reorganization of the pentenyl chain was required for olefin β-migratory insertion?.46b
  • 90
    • 2442718401 scopus 로고    scopus 로고
    • note
    • ‡ for the conversion of 5 to 6 relative to the conversion of 14 to 15 is due to migration of a Pd-secondary alkyl group in the case of 5 and a palladium-primary alkyl group in the case of 14.
  • 91
    • 2442703589 scopus 로고    scopus 로고
    • note
    • 1H NMR analysis under these conditions.
  • 94
    • 2442664744 scopus 로고    scopus 로고
    • note
    • Alternatively, Pd-C bond cleavage could occur via an oxidative addition/reductive elimination sequence.
  • 95
    • 2442710924 scopus 로고    scopus 로고
    • note
    • 3) generated in the catalytic silane competition experiments.
  • 96
    • 2442653472 scopus 로고    scopus 로고
    • note
    • 3 formed (3,3-dimethylbutyl)triethylsilane to the exclusion of (3,3-dimethylbutyl)triphenylsilane,14 which indicates that olefin insertion/silylation of 4e is much faster than is silyl exchange. Because NCAr and an olefin of 1 are of comparable ligating ability with respect to cationic Pd(II) complexes,36 this result strongly suggests that 4b does not undergo silyl exchange prior to conversion to 5.
  • 97
    • 2442696003 scopus 로고    scopus 로고
    • note
    • ‡ should be destabilized by the decreasing electron density and increasing steric bulk of the silane.
  • 98
    • 2442710923 scopus 로고    scopus 로고
    • note
    • 1/2 = 22 min at -41 °C) ensures rapid activation of precatalyst 2b relative to catalyst turnover.
  • 99
    • 2442688615 scopus 로고    scopus 로고
    • note
    • 3 corresponds to a macroscopic rate constant for the conversion of 6 to 4b for the specific case where [NCAr] = 42 mM.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.