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H. Steinmetz, K. Gerth, R. Jansen, N. Schläger, R. Dehn, S. Reinecke, A. Kirschning, R. Müller, Angew. Chem. 2011, 123, 553-557
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Gerth, K.2
Jansen, R.3
Schläger, N.4
Dehn, R.5
Reinecke, S.6
Kirschning, A.7
Müller, R.8
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3
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79954594267
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R. Jansen, K. Gerth, H. Steinmetz, S. Reinecke, W. Kessler, A. Kirschning, R. Müller, unpublished results
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R. Jansen, K. Gerth, H. Steinmetz, S. Reinecke, W. Kessler, A. Kirschning, R. Müller, unpublished results.
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6
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0041810236
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38949203821
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T. Nguyen, K. Ishida, H. Jenke-Kodama, E. Dittmann, C. Gurgui, T. Hochmuth, S. Taudien, M. Platzer, C. Hertweck, J. Piel, Nat. Biotechnol. 2008, 26, 225-233.
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Dittmann, E.4
Gurgui, C.5
Hochmuth, T.6
Taudien, S.7
Platzer, M.8
Hertweck, C.9
Piel, J.10
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11
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0025019734
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N. S. Scrutton, A. Berry, R. N. Perham, Nature 1990, 343, 38-43.
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Scrutton, N.S.1
Berry, A.2
Perham, R.N.3
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13
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79954604909
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Additionally, the presence of the alkyne group paves the way for a biomimetic total synthesis approach
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Additionally, the presence of the alkyne group paves the way for a biomimetic total synthesis approach.
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14
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79954579794
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Throughout the text atom numbering refers to the numbering of in the natural product elansolid
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Throughout the text atom numbering refers to the numbering of in the natural product elansolid.
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15
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79954593371
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note
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To the best of our knowledge no examples of IMDA cycloadditions with a tertiary alcohol in allylic position to the diene have been described so far. In simpler cases, the stereoinduction of this center varies from moderate to excellent, see
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16
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0021216829
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M. P. Edwards, S. V. Ley, S. G. Lister, P. D. Palmer, D. J. Williams, J. Org. Chem. 1984, 49, 3503-3516
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Edwards, M.P.1
Ley, S.V.2
Lister, S.G.3
Palmer, P.D.4
Williams, D.J.5
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19
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79954618815
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1H NMR spectrum of the corresponding ester
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1H NMR spectrum of the corresponding ester
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21
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0942277395
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J. M. Seco, E. Qunioa, R. Riguera, Chem. Rev. 2004, 104, 17-117.
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Seco, J.M.1
Qunioa, E.2
Riguera, R.3
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22
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20444505606
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T. Motozaki, K. Sawamura, A. Suzuki, K. Yoshida, T. Ueki, A. Ohara, R. Munakata, K. Takao, K. Tadano, Org. Lett. 2005, 7, 2261-2264.
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Sawamura, K.2
Suzuki, A.3
Yoshida, K.4
Ueki, T.5
Ohara, A.6
Munakata, R.7
Takao, K.8
Tadano, K.9
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24
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79954582304
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We had to choose an oxidation method that works well at temperatures as low as -30°C because the intermediate aldehyde spontaneously underwent an IMDA reaction at 0°C to yield tetrahydroindanes 27a, b as diastereomers (1:1) resulting from both endo transition states TS-I and TS-II.
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We had to choose an oxidation method that works well at temperatures as low as -30°C because the intermediate aldehyde spontaneously underwent an IMDA reaction at 0°C to yield tetrahydroindanes 27a, b as diastereomers (1:1) resulting from both endo transition states TS-I and TS-II.
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25
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0019125839
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The p-TMS substituent was chosen as an alternative, because it can be transferred readily into a phenolic OH group
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The p-TMS substituent was chosen as an alternative, because it can be transferred readily into a phenolic OH group:, R. L. Funk, K. P. C. Vollhardt, J. Am. Chem. Soc. 1980, 102, 5253-5261.
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Funk, R.L.1
Vollhardt, K.P.C.2
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26
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79954604002
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Instead, only deprotection of the PMB ether was observed
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Instead, only deprotection of the PMB ether was observed.
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-
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27
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79954587865
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note
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This high propensity to cyclization can be explained by 1) a low-energy LUMO of the dienophile, 2) a high-energy HOMO of the diene on account of conjugation to the alkyne, and 3) a double Thorpe-Ingold effect caused by the gem-dimethyl group and the tertiary alcohol. However, the gene analysis shown in Scheme 2 almost excludes the possibility of an IMDA precursor bearing a keto group at C25.
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-
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28
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79954608167
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See the Supporting Information for details on the analytical assignments
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See the Supporting Information for details on the analytical assignments.
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30
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79954614146
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noteworthy, when the weaker acid AcOH in dioxane was employed instead, no IMDA products could be detected
-
noteworthy, when the weaker acid AcOH in dioxane was employed instead, no IMDA products could be detected.
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-
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31
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78650012665
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note
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While this manuscript was under review, Piel and co-workers disclosed a biosynthetic proposal for the elansolids, suggesting a rearranged allyl benzyl alcohol (similar to 6) as the direct substrate for the IMDA reaction. From our perspective, the electronic requirements for the IMDA cycloaddition are fulfilled only when the quinone methide moiety is involved as the key biosynthesis intermediate:, R. Teta, M. Gurgui, E. J. N. Helfrich, S. Künne, A. Schneider, G. Van Echten-Deckert, A. Mangoni, J. Piel, ChemBioChem 2010, 11, 2506-2512.
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(2010)
ChemBioChem
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, pp. 2506-2512
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Teta, R.1
Gurgui, M.2
Helfrich, E.J.N.3
Künne, S.4
Schneider, A.5
Van Echten-Deckert, G.6
Mangoni, A.7
Piel, J.8
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