- Asymmetric total synthesis of onoseriolide, bolivianine, and isobolivianine
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In this article, we describe our efforts on the total synthesis of bolivianine (1) and isobolivianine (2), involving the synthesis of onoseriolide (3). The first generation synthesis of bolivianine was completed in 21 steps by following a chiral resolution strategy. Based on the potential biogenetic relationship between bolivianine (1), onoseriolide (3), and β-(E)-ocimene (8), the second generation synthesis of bolivianine was biomimetically achieved from commercially available (+)-verbenone in 14 steps. The improved total synthesis features an unprecedented palladium-catalyzed intramolecular cyclopropanation through an allylic metal carbene, for the construction of the ABC tricyclic system, and a Diels-Alder/intramolecular hetero-Diels-Alder (DA/IMHDA) cascade for installation of the EFG tricyclic skeleton with the correct stereochemistry. Transformation from bolivianine to isobolivianine was facilitated in the presence of acid. The biosynthetic mechanism and the excellent regio- and endo selectivities in the cascade are well supported by theoretical chemistry based on the DFT calculations. From terpenes to terpenes: Two strategies toward the synthesis of bolivianine are described. Based on the modified biogenetic hypothesis, biomimetic total synthesis was evolved and accomplished, involving onoseriolide, bolivianine, and isobolivianine (see figure). Experimental results and DFT calculations support a Diels-Alder/intramolecular hetero-Diels-Alder (DA/IMHDA) cascade leading to bolivianine. In addition, the synthesis features a new Pd-catalyzed intramolecular cyclopropanation. Copyright
- Du, Biao,Yuan, Changchun,Yu, Tianzi,Yang, Li,Yang, Yang,Liu, Bo,Qin, Song
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p. 2613 - 2622
(2014/03/21)
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- Bioinspired total synthesis of bolivianine: A diels-alder/intramolecular hetero-Diels-Alder cascade approach
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We report the first total synthesis of bolivanine in a 14-step pathway involving the synthesis of onoseriolide. Our synthesis features a palladium-catalyzed intramolecular cyclopropanation involving an allylic metal carbene and a Diels-Alder/intramolecular hetero-Diels-Alder cascade, allowing the single-step assembly of a tricyclic system with proper configuration. The synthetic efforts validate our modified biogenetic hypothesis and allow us to confirm the absolute configuration of bolivianine.
- Yuan, Changchun,Du, Biao,Yang, Li,Liu, Bo
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p. 9291 - 9294
(2013/07/26)
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