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1
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85031210973
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note
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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.
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3
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0029038016
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Torregiani, E.; Rafaiani, G.; Barboni, L.; Appendino, G. Tetrahedron Lett. 1995, 7127-7128.
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(1995)
Tetrahedron Lett.
, pp. 7127-7128
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Torregiani, E.1
Rafaiani, G.2
Barboni, L.3
Appendino, G.4
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4
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0027969302
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Vander Velde, D.G.; Georg, G.I.; Gollapudi, S.R.; Jampani, H.B.; Liang, X.-Z.; Mitscher, L.A.; Ye, Q.-M. J Nat. Prod. 1994, 57, 862-867.
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(1994)
J Nat. Prod.
, vol.57
, pp. 862-867
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Vander Velde, D.G.1
Georg, G.I.2
Gollapudi, S.R.3
Jampani, H.B.4
Liang, X.-Z.5
Mitscher, L.A.6
Ye, Q.-M.7
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5
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0011977466
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Appendino, G.; Fenoglio, I.; Cravotto, G.; Varese, M.; Gariboldi, P.; Gabetta, B. Gazz. Chim. Ital. 1994, 24, 253-257.
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(1994)
Gazz. Chim. Ital.
, vol.24
, pp. 253-257
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Appendino, G.1
Fenoglio, I.2
Cravotto, G.3
Varese, M.4
Gariboldi, P.5
Gabetta, B.6
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6
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85031221403
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note
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13C NMR spectra of 3 and 5 were assigned with the aid of NOE-inspection and the HMBC spectra
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7
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0027418091
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Chen, S.-H.; Huang, S.; Wei, J.; Farina, V. Tetrahedron 1993, 49, 2805-2828.
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(1993)
Tetrahedron
, vol.49
, pp. 2805-2828
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Chen, S.-H.1
Huang, S.2
Wei, J.3
Farina, V.4
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8
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0342628418
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in press
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Gabetta, B.; Peterlongo, F.; Zini, G.; Barboni, L.; Rafaiani, G.; Ranzuglia, P.; Torregiani, E.; Appendino, G.; Cravotto, G. Phytochemistry 1995 (in press)
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(1995)
Phytochemistry
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Gabetta, B.1
Peterlongo, F.2
Zini, G.3
Barboni, L.4
Rafaiani, G.5
Ranzuglia, P.6
Torregiani, E.7
Appendino, G.8
Cravotto, G.9
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9
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33947086888
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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).
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(1973)
J. Am. Chem. Soc
, vol.95
, pp. 5065-5067
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Bürgi, H.B.1
Dunitz, J.D.2
Shefter, E.3
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10
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85031224681
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note
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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
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11
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0019422654
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Miller, R.W., Powell, R.G.; Smith Jr., C.R., Arnold, E.; Clardy, J. J. Org. Chem. 1981, 46, 1469-1474.
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(1981)
J. Org. Chem.
, vol.46
, pp. 1469-1474
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Miller, R.W.1
Powell, R.G.2
Smith C.R., Jr.3
Arnold, E.4
Clardy, J.5
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12
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37049125296
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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.
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(1967)
J. Chem. Soc. (C)
, pp. 452-462
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Eyre, D.H.1
Harrison, J.W.2
Lythgoe, B.3
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13
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0003897919
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Farina, V. Ed., Elsevier
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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.
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(1995)
The Chemistry and Pharmacology of Taxol® and Its Derivatives
, pp. 13-18
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Appendino, G.1
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14
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0028284948
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For the rearrangement of a baccatin III derivative into a stable 2,4,20-orthoester, see: Appendino, G.; Varese, M.; Gariboldi, P.; Gabetta, B. Tetrahedron Lett. 1994, 2217-2220.
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(1994)
Tetrahedron Lett.
, pp. 2217-2220
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Appendino, G.1
Varese, M.2
Gariboldi, P.3
Gabetta, B.4
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15
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85031230585
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note
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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).
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16
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85031224380
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note
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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.
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17
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85031220257
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note
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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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