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Volumn 37, Issue 5, 1996, Pages 727-730

Acid and base catalysed rearrangements of 9,10-dioxotaxanes

Author keywords

[No Author keywords available]

Indexed keywords

TAXANE DERIVATIVE;

EID: 0030053969     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/0040-4039(95)02254-6     Document Type: Article
Times cited : (15)

References (17)
  • 1
    • 85031210973 scopus 로고    scopus 로고
    • note
    • Part XXIV in the series The Chemistry and Occurrence of Taxane Derivatives. For part XXIII, see reference 3 This paper is dedicated to the memory of Pierluigi Gariboldi, with whom we would have loved to share the excitement of natural products research for a much longer time.
  • 6
    • 85031221403 scopus 로고    scopus 로고
    • note
    • 13C NMR spectra of 3 and 5 were assigned with the aid of NOE-inspection and the HMBC spectra
  • 9
    • 33947086888 scopus 로고
    • To avoid electrostatic repulsion by the oxygen lone-pairs, nucleophiles approach a carbonyl group at an angle of about 107° (Bürgi, H.B., Dunitz, J.D., Shefter, E. J. Am. Chem. Soc 1973, 95, 5065-5067).
    • (1973) J. Am. Chem. Soc , vol.95 , pp. 5065-5067
    • Bürgi, H.B.1    Dunitz, J.D.2    Shefter, E.3
  • 10
    • 85031224681 scopus 로고    scopus 로고
    • note
    • Models show that the attack to the C-10 carbonyl is favoured by a negative torsion angle around C-9, C-10, whereas a positive torsion angle C-9, C-10 favours attack to the C-9 carbonyl
  • 12
    • 37049125296 scopus 로고
    • The bidimensional representation of 5 was done according to the Lythgoe convention, that is, the substituents at the bridgehead carbons (C-1, C-8, C-11, C-12) are considered as cyclooctane ring B substituents (Eyre, D.H.; Harrison, J.W.; Lythgoe, B. J. Chem. Soc. (C) 1967, 452-462). For sake of clarity, an alternative and unambiguous representation is also given in Scheme 3. Note that the stereochemical descriptors of the substituents at C-1, C-8, C-11, and C-12 are inverted. For a discussion of the bidimensional representation of taxoids, see: Appendino, G. in The Chemistry and Pharmacology of Taxol® and its Derivatives, Farina, V. Ed., Elsevier, 1995; pp. 13-18.
    • (1967) J. Chem. Soc. (C) , pp. 452-462
    • Eyre, D.H.1    Harrison, J.W.2    Lythgoe, B.3
  • 13
    • 0003897919 scopus 로고
    • Farina, V. Ed., Elsevier
    • The bidimensional representation of 5 was done according to the Lythgoe convention, that is, the substituents at the bridgehead carbons (C-1, C-8, C-11, C-12) are considered as cyclooctane ring B substituents (Eyre, D.H.; Harrison, J.W.; Lythgoe, B. J. Chem. Soc. (C) 1967, 452-462). For sake of clarity, an alternative and unambiguous representation is also given in Scheme 3. Note that the stereochemical descriptors of the substituents at C-1, C-8, C-11, and C-12 are inverted. For a discussion of the bidimensional representation of taxoids, see: Appendino, G. in The Chemistry and Pharmacology of Taxol® and its Derivatives, Farina, V. Ed., Elsevier, 1995; pp. 13-18.
    • (1995) The Chemistry and Pharmacology of Taxol® and Its Derivatives , pp. 13-18
    • Appendino, G.1
  • 15
    • 85031230585 scopus 로고    scopus 로고
    • note
    • 3, TMS as reference, resonances of the major anomer): δ 206.2 (s, C-9), 201.8 (s, C-10), 170.2 (s, Ac), 165.7 (s, Bz), 132.6 (d, Bz), 131.8 (s, Bz), 129.6 (d, Bz), 128.3 (d, Bz), 100.5 (d, C-7), 94.5 (s, C-4), 84.7 (d, C-5), 83.8 (s, C-1), 78.1 (d, C-2), 72.7 (d, C-13), 67.6 (t, C-20), 59.1 (d, C-11), 53.2 (d, C-3), 52.8 (s, C-8), 43.7 (s, C-12), 43.6 (s, C-15), 41.1 (t, C-6), 38.3 (t, C-14), 28.8 (q, C-16), 28.0 (q, C-18), 21.1 (q, C-17), 20.8 (q, Ac), 184 (q, C-19).
  • 16
    • 85031224380 scopus 로고    scopus 로고
    • note
    • The H-5/H-20a,b NOE correlations are especially relevant They show that the rearrangement takes place with an overall retention of configuration at C-5, implying two Sn2-type displacements (see Scheme 3). The cis-relationship between the 19-methyl and H-20a,b is evidenced in the alternative representation of 5.
  • 17
    • 85031220257 scopus 로고    scopus 로고
    • note
    • 6 was ca 1:1. Acetylation of 5 afforded an easily separable mixture of anomeric acetates in a cα 1:1 ratio.


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