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Volumn 71, Issue 25, 2006, Pages 9297-9301

Unexpected stereodynamic consequences of the restricted rotations in ortho-acyl- and ortho-vinyl biphenyls

Author keywords

[No Author keywords available]

Indexed keywords

CHEMICAL MODIFICATION; DERIVATIVES; SUBSTITUTION REACTIONS;

EID: 33845547585     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo0613131     Document Type: Article
Times cited : (14)

References (35)
  • 15
    • 33845541495 scopus 로고    scopus 로고
    • note
    • -1, respectively). Such a large difference means that only the E rotamer is essentially populated in 1-3, thus explaining why the effects of the restricted Ph-C=O rotation cannot be observed.
  • 16
    • 33845522777 scopus 로고    scopus 로고
    • note
    • In the transition state of the aryl-aryl bond rotation of 1, the HC= O group, according to DFT calculations, remains nearly coplanar, and thus still able to conjugate, with the phenyl ring.
  • 17
    • 33845531592 scopus 로고    scopus 로고
    • note
    • -1), and thus the different populations observed by NMR depend on the condensed phase. We arbitrarily identified the less hindered conformer (having the two substituents in an anti relationship) as the more populated form in solution.
  • 18
    • 33845548665 scopus 로고    scopus 로고
    • PC version of QCPE program no. 633, Indiana University, Bloomington, IN
    • PC version of QCPE program no. 633, Indiana University, Bloomington, IN.
  • 19
    • 33845513221 scopus 로고    scopus 로고
    • note
    • tBu rotation barrier had been lower than that for the Ar-Ar rotation, again the methyl line would first split into two, with a 1:1 ratio, because the slow Ar-Ar rotation would also make the molecule chiral. In both cases, only subsequently would four lines be detectable, that is, when also the second motion is frozen at a lower temperature, thus creating two chiral conformers. Because such a two-step process was not observed, in that the single signal splits directly into four, the two exchange pathways, leading to the coalescence of the 1:1 and of the 65:35 pairs of methyl lines, must occur almost simultaneously. This implies that the two barriers must be very similar, as proved by the fact that a single rate constant is sufficient for the simulation.
  • 20
    • 33845522981 scopus 로고    scopus 로고
    • MMFF force field as in PC model v 7.5, Serena Software, Bloomington, IN
    • MMFF force field as in PC model v 7.5, Serena Software, Bloomington, IN.
  • 27
    • 33845537130 scopus 로고    scopus 로고
    • note
    • 2 group. The two groups thus display an analogous steric effect upon the Ar-Ar rotation.
  • 28
    • 33845528452 scopus 로고    scopus 로고
    • note
    • 13C lines of 6 split into two signals with a 75:25 proportion, due to two diastereomeric conformers being created by two stereogenic axes. The major spectrum has been arbitrarily assigned to the less hindered conformer, that is, that with the two substituents in an anti relationship.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.