- Formal Total Synthesis of Diazonamide A by Indole Oxidative Rearrangement
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A short formal total synthesis of the marine natural product diazonamide A is described. The route is based on indole oxidative rearrangement, and a number of options were investigated involving migration of tyrosine or oxazole fragments upon oxidation of open chain or macrocyclic precursors. The final route proceeds from 7-bromoindole by sequential palladium-catalysed couplings of an oxazole fragment at C-2, followed by a tyrosine fragment at C-3. With the key 2,3-disubstituted indole readily in hand, formation of a macrocyclic lactam set the stage for the crucial oxidative rearrangement to a 3,3-disubstituted oxindole. Notwithstanding the concomitant formation of the unwanted indoxyl isomer, the synthesis successfully delivered, after deprotection, the key oxindole intermediate, thereby completing a formal total synthesis of diazonamide A.
- David, Nadège,Pasceri, Raffaele,Kitson, Russell R. A.,Pradal, Alexandre,Moody, Christopher J.
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supporting information
p. 10867 - 10876
(2016/07/27)
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- Total synthesis of TMC-95A and -B via a new reaction leading to Z-enamides. Some preliminary findings as to SAR
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A full account of the total syntheses of proteasome inhibitors TMC-95A and -B is provided. A key feature of the syntheses involved installation of a cis-propenylamide moiety by a thermal rearrangement of an α-silylallyl amide. The scope and mechanism of the enamide-forming reaction are discussed. Also provided are some preliminary results from SAR studies. It was found that simplified analogues can retain the full potency of proteasome inhibition.
- Lin, Songnian,Yang, Zhi-Qiang,Kwok, Benjamin H. B.,Koldobskiy, Michael,Crews, Craig M.,Danishefsky, Samuel J.
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p. 6347 - 6355
(2007/10/03)
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- Preparation of selectively protected L-dopa derivatives: Oxidation of tyrosine-3-boronates
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Conversion of 3-iodo-L-tyrosine to protected tyrosine-3-boronate esters, followed by oxidation with hydrogen peroxide, provides a mild and efficient method for the preparation of selectively protected L-dopa derivatives.
- Hunter, Luke,Hutton, Craig A.
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p. 1095 - 1098
(2007/10/03)
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- The total synthesis of proteasome inhibitors TMC-95A and TMC-95B: Discovery of a new method to generate cis-propenyl amides
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Silatropic and ene-like bond reorganizations (see scheme, left) were the key steps in the first total synthesis of the title compounds, which only differ in stereochemistry at the remote C36 stereocenter. Other key steps include a Suzuki biaryl construction, a diastereofacial dihydroxylation reaction, and a macrolactamization.
- Lin, Songnian,Danishefsky, Samuel J.
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p. 512 - 515
(2007/10/03)
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