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Volumn , Issue 5, 2001, Pages 947-955

The "tocopherol-acetaminophen reaction" - A new [1,4]-rearrangement discovered in vitamin E chemistry

Author keywords

Isotopic labeling; Protecting groups; Reaction mechanisms; Rearrangements; Vitamins

Indexed keywords

ALPHA TOCOPHEROL; PARACETAMOL;

EID: 0035114832     PISSN: 1434193X     EISSN: None     Source Type: Journal    
DOI: 10.1002/1099-0690(200103)2001:5<947::AID-EJOC947>3.0.CO;2-R     Document Type: Article
Times cited : (5)

References (32)
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    • The reductant can be either a separate coreactant, cf. ref. [2], or the "former" 5a-substituent, cf.: T. Rosenau, W. D. Habicher, Chem. Pharm. Bull. 1997, 45, 1080-1084.
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    • Rosenau, T.1    Habicher, W.D.2
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    • Reactivity and preparation of ortho-quinone methides: [10a] L. Jurd, J. N. Roitman, Tetrahedron 1979, 35, 1567-1574.
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    • Jurd, L.1    Roitman, J.N.2
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    • Trapping of 4 in organic syntheses with vinyl type structures: [10b] D. A. Bolon, J. Org. Chem. 1970, 35, 3666-3671.
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    • note
    • Formation of dimeric products other than spiro-dimer 5 is a sensitive indicator for detection of homolytic processes in a reaction system. On the basis of these reactions, 1 is frequently applied as a reporter molecule for homolytic reactions, especially if the radical concentration is too low for EPR detection, or if the system is unsuitable for EPR experiments.
  • 19
    • 20344387039 scopus 로고    scopus 로고
    • note
    • By setting the values for the two dihedrals in 10° intervals, a 36 × 36 matrix of optimized energies was obtained for compounds 8a to 81. For many dihedrals, the proximity of substituent atoms and the tocopherol moiety resulted in strong steric repulsion, and thus in unstable geometries. The additional steric constraint with bulky substituents, such as in 8k or in 81, was clearly evident.
  • 20
    • 20344380255 scopus 로고    scopus 로고
    • note
    • The exact values for the dihedral angles C-6-C-5-C-5a-O and C-5-C-5a-O-C-1′ are 46.2° and -103.5° for Toc-acetaminophen (8a), 45.9° and -101.4° for 8i, and 46.4° and -101.9° for 8j. The stabilization gained by adopting this geometry can be visualized by considering the rotational barrier for the bond C-5a-O, which corresponds to a change of the dihedral angle C-5-C-5a-O-C-1′. For deprotonated Tocacetaminophen (8a) the rotational barrier was 31 kJ/mol, and the values for 8i and 8j were 26 kJ/mol and 29 kJ/mol, respectively. For the bulky 4′-N-acyl substituents (8k and 81) the rotational barrier was lower at 23 kJ/mol. Interestingly, neutral (i.e., not deprotonated) 8a exhibited only a shallow energy minimum of 19 kJ/mol at slightly altered dihedral angles (C-6-C-5-C-5a-O: 45.4° and C-5-C-5a-O-C-1′: -104.9°).
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    • [18a] IUPAC-IUB Commission on Biochemical Nomenclature (CBN), Arch. Biochim. Biophys. 1974, 165, 1-8.
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    • [18b] IUPAC-IUB, Eur. J. Biochim. 1982, 123, 473-475.
    • (1982) Eur. J. Biochim. , vol.123 , pp. 473-475


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.