Short Approach toward the Nonracemic A,B,E Tricyclic Core of Calyciphylline B-Type Alkaloids

Boissarie, Patrick; Bélanger, Guillaume

doi:10.1021/acs.orglett.7b01566

Cited by 27 publications

(16 citation statements)

References 35 publications

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“…At this stage, we drew inspiration from the Bélanger lab's work targeting the core ring structure of calyciphylline B type alkaloids. 21 They trap an aldehyde aldol as the 1,3-dioxa-2-silacyclohexene, and use this motif to template a Vilsmeier-Haack cyclization. A similar silacycle should template our proposed IMDA reaction.…”

Section: Figure 2 Retrosynthetic Analysis and Calculations Of Ring Strain Energiesmentioning

confidence: 99%

Total Synthesis of (±)-Illisimonin A, a Neuroprotective Sesquiterpenoid from the Fruits of Illicium simonsii

Burns¹,

Rychnovsky

2019

Preprint

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<p>Illisimonin A was isolated from Illicium simonsii and has a previously unreported tricyclic carbon framework. It displayed neuroprotective effects against oxygen-glucose deprivation-induced cell injury in SH-SY5Y cells. It incorporates a highly strained trans-pentalene ring system. We report the first synthesis of illisimonin A. Notable steps in the route include a 1,3-dioxa-2-silacyclohexenetemplated Diels-Alder cycloaddition and type-3 semipinacol rearrangement to generate the trans-pentalene. The final step is an iron-catalyzed C-H oxidation. The synthetic route is robust, with 94 mg prepared in a single pass.</p>

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Section: Figure 2 Retrosynthetic Analysis and Calculations Of Ring Strain Energiesmentioning

confidence: 99%

Total Synthesis of (±)-Illisimonin A, a Neuroprotective Sesquiterpenoid from the Fruits of Illicium simonsii

Burns¹,

Rychnovsky

2019

Preprint

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show abstract

“…At this stage, we drew inspiration from the Beĺanger lab's work targeting the core ring structure of calyciphylline B type alkaloids. 23 They trap an aldehyde aldol as the 1,3-dioxa-2-silacyclohexene, and use this motif to template a Vilsmeier−Haack cyclization. A similar silacycle should template our proposed IMDA reaction.…”

mentioning

confidence: 99%

“…Next, an aldol reaction united vinylogous ester with known ketone 7 (available in 3 or 5 steps from commercial material), to afford tertiary alcohol 11 as a mixture of diastereomers. At this stage, we drew inspiration from the Bélanger lab’s work targeting the core ring structure of calyciphylline B type alkaloids . They trap an aldehyde aldol as the 1,3-dioxa-2-silacyclohexene, and use this motif to template a Vilsmeier–Haack cyclization.…”

mentioning

confidence: 99%

Total Synthesis and Structure Revision of (−)-Illisimonin A, a Neuroprotective Sesquiterpenoid from the Fruits of Illicium simonsii

Burns

Rychnovsky

2019

J. Am. Chem. Soc.

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Illisimonin A was isolated from Illicium simonsii and has a previously unreported tricyclic carbon framework. It displayed neuroprotective effects against oxygen-glucose deprivation-induced cell injury in SH-SY5Y cells. It incorporates a highly strained trans-pentalene ring system. We report the first synthesis of (±)-illisimonin A. Notable steps in the route include a 1,3-dioxa-2-silacyclohexene templated Diels–Alder cycloaddition and type-3 semipinacol rearrangement to generate the trans-pentalene. The final step is an iron-catalyzed C–H oxidation. The synthetic route is robust, with 94 mg of racemic material prepared in a single pass. Resolving an intermediate enabled the synthesis of natural (−)-illisimonin A. The absolute configuration of (−)-illisimonin A was revised to 1S,4S,5S,6S,7R,9R,10R based on the X-ray structure of a heavy-atom analogue.

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“…Given the limited synthetic studies focusing on the calyciphylline B-type subfamily, 17 and their fascinating architectures, we embarked on a synthesis of these compounds. Herein, we detail studies which have culminated in total syntheses of (−)-daphlongamine H ( 4 ) and (−)-isodaphlongamine H ( 5 ).…”

mentioning

confidence: 99%

Calyciphylline B-Type Alkaloids: Total Syntheses of (−)-Daphlongamine H and (−)-Isodaphlongamine H

2019

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The first total synthesis of the complex hexacylic Daphniphyllum alkaloid (−)-daphlongamine H has been accomplished. Key to the success of the strategy are a complexity-building Mannich reaction, efficient cyclizations, and a highly diastereoselective hydrogenation to assemble multigram quantities of the tricyclic core bearing four contiguous stereocenters. Following construction of the hydro-indene substructure by means of a Pauson–Khand reaction, endgame redox manipulations delivered the natural product. Importantly, the synthetic studies have also given access to (−)-isodaphlongamine H and led to a revision of the reported structure of deoxyisocalyciphylline B.

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Short Approach toward the Nonracemic A,B,E Tricyclic Core of Calyciphylline B-Type Alkaloids

Cited by 27 publications

References 35 publications

Total Synthesis of (±)-Illisimonin A, a Neuroprotective Sesquiterpenoid from the Fruits of Illicium simonsii

Total Synthesis of (±)-Illisimonin A, a Neuroprotective Sesquiterpenoid from the Fruits of Illicium simonsii

Total Synthesis and Structure Revision of (−)-Illisimonin A, a Neuroprotective Sesquiterpenoid from the Fruits of Illicium simonsii

Calyciphylline B-Type Alkaloids: Total Syntheses of (−)-Daphlongamine H and (−)-Isodaphlongamine H

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