- Chemo-enzymatic synthesis of equisetin
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We here report that the biosynthesis of equisetin, a fungal tetramate natural product with potent anti-infectious activity, relies on Fsa2, a Diels-Alderase that constructs the trans-decalin system of the molecule in a stereo-selective manner. This finding led to the development of a concise chemo-enzymatic route toward the synthesis of equisetin, which involves facile preparation of a linear polyene precursor via 7-steps and Fsa2 activity for equisetin maturation through an intramolecular Diels-Alder reaction, thus exemplifying the significance of the combination of chemical and biological methods to achieve structurally complex cyclic natural products and their derivatives.
- Li, Xiaojun,Zheng, Qingfei,Yin, Jun,Liu, Wen,Gao, Shuanhu
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- Total synthesis of the Fusarium toxin equisetin: Proof of the stereochemical relationship of the tetramate and terpenoid sectors
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A total synthesis of the Fusarium mycotoxin equisetin, in a manner that establishes its stereochemistry, is described. The key steps involve a lactonic variation of the ester enolate Claisen rearrangement and a novel construction of a 1-acyltetramic acid from an L-N-methylserine derivative and a β-keto ester.
- Turos,Audia,Danishefsky
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- Biomimetic synthesis of equisetin and (+)-fusarisetin A
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(+)-FusarisetinA belongs to a group of acyl tetramic acid natural products that show potential anticancer activity. Equisetin, a biogenetically related acyl tetramic acid, contains the basic skeleton of (+)-fusarisetinA. We proposed that equisetin and (+)-fusarisetinA share a biosynthetic pathway that starts with naturally occurring (S)-serine and an unsaturated fatty acid. In support of this hypothesis, we have demonstrated that a cyclization sequence involving an intramolecular Diels-Alder reaction followed by a Dieckmann cyclization of polyenoylamino acid yielded equisetin. The aerobic oxidation of equisetin, promoted by either MnIII/O2 or a reactive oxygen species (ROS) produced by visible-light chemistry, gave peroxyfusarisetin, which could be easily reduced to (+)-fusarisetinA. We report herein detailed information on the biogenetic synthesis of equisetin and (+)-fusarisetinA. Make the change to bio! Biomimetic synthesis of equisetin and (+)-fusarisetinA was achieved based on a biosynthetic hypothesis. An intramolecular Diels-Alder reaction followed by a Dieckmann cyclization of polyenoylamino ester furnished equisetin. The aerobic oxidation of equisetin to give (+)-fusarisetinA was mediated by a MnIII/O2 system or reactive oxygen species (ROS) (see scheme). Copyright
- Yin, Jun,Kong, Lili,Wang, Cheng,Shi, Yingbo,Cai, Shujun,Gao, Shuanhu
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supporting information
p. 13040 - 13046
(2013/10/01)
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- Enantioselective total synthesis of (-)-equisetin using a Me3Al-mediated intramolecular Diels-Alder reaction
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An efficient and enantioselective total synthesis of (-)-equisetin 1 has been accomplished using a diastereoselective Me3Al-mediated intramolecular Diels-Alder (IMDA) reaction as a key reaction step.
- Yuki, Kumiko,Shindo, Mitsuru,Shishido, Kozo
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p. 2517 - 2519
(2007/10/03)
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