An Enantioselective Synthesis of the ABD Tricycle for (−)‐Phomactin A Featuring Rawal’s Asymmetric Diels–Alder Cycloaddition

You, Lingfeng; Hsung, Richard P.; Bedermann, Aaron A.; Kurdyumov, Aleksey V.; Tang, Yu; Buchanan, Grant; Cole, Kevin P.

doi:10.1002/adsc.200800552

Cited by 29 publications

(13 citation statements)

References 80 publications

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“…Scheme ) as a racemate. As indicated, a Diels–Alder reaction between tiglic aldehyde ( 16 ) and Rawal diene 17 , in THF at 50 °C for 16 h, followed by treatment with aq. HCl, smoothly afforded the desired enone.…”

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confidence: 99%

Total Syntheses of Scaparvins B, C, and D Enabled by a Key C–H Functionalization

Snyder

2017

J. Am. Chem. Soc.

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The clerodane diterpene family possesses an impressive range of bioactivities and high synthetic challenge due to their unique amalgamation of rings, stereocenters, and oxygenation. Herein, we disclose the first total syntheses of three members, scaparvins B, C, and D, through a route fueled by several chemoselective and carefully orchestrated steps. One such operation is a tailored late-stage C-H functionalization converting a carboxylic acid into a lactone through the oxidation of a tertiary C-H bond under conditions that minimize epoxidation of an alkene. This step, among others, afforded critical functionality to complete the targets. In addition, use of an appropriate chiral catalyst with a Rawal diene renders the sequence enantioselective.

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confidence: 99%

Total Syntheses of Scaparvins B, C, and D Enabled by a Key C–H Functionalization

Snyder

2017

J. Am. Chem. Soc.

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“…Amino silyloxy butadienes are a class of highly reactive compounds that have demonstrated tremendous utility in natural product synthesis 1 2 3 4 5 6 7 8 and asymmetric catalysis 9 10 11 12 13 . In 1997, Rawal and colleagues 14 15 reported the first general synthesis of 1-amino-3-silyloxybutadienes from vinylogous amides.…”

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confidence: 99%

Synthesis of tetrasubstituted 1-silyloxy-3-aminobutadienes and chemistry beyond Diels–Alder reactions

Peng

et al. 2015

Nat Commun

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Electron-rich dienes have revolutionized the synthesis of complex compounds since the discovery of the legendary Diels–Alder cycloaddition reaction. This highly efficient bond-forming process has served as a fundamental strategy to assemble many structurally formidable molecules. Amino silyloxy butadienes are arguably the most reactive diene species that are isolable and bottleable. Since the pioneering discovery by Rawal, 1-amino-3-silyloxybutadienes have been found to undergo cycloaddition reactions with unparalleled mildness, leading to significant advances in both asymmetric catalysis and total synthesis of biologically active natural products. In sharp contrast, this class of highly electron-rich conjugated olefins has not been studied in non-cycloaddition reactions. Here we report a simple synthesis of tetrasubstituted 1-silyloxy-3-aminobutadienes, a complementarily substituted Rawal's diene. This family of molecules is found to undergo a series of intriguing chemical transformations orthogonal to cycloaddition reactions. Structurally diverse polysubstituted ring architectures are established in one step from these dienes.

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“…Our synthesis commenced with a-allylation of isobutyraldehyde with known reagent (E)-1,3-dibromobut-2-ene (7), [18] followed by Wittig homologation to afford alkenyl bromide 9 (Scheme 4). Subsequent addition of the lithium salt of 9 to cyclobutanone delivers allylic alcohol 10.…”

Section: Methodsmentioning

confidence: 99%

Enantioselective Catalytic Aldehyde α‐Alkylation/Semipinacol Rearrangement: Construction of α‐Quaternary‐δ‐Carbonyl Cycloketones and Total Synthesis of (+)‐Cerapicol

Yang

Zhang

et al. 2020

Angew Chem Int Ed

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An enantioselective aldehyde α‐alkylation/semipinacol rearrangement was achieved through organo‐SOMO catalysis. The catalytically generated enamine radical cation serves as a carbon radical electrophile that can stereoselectively add to the alkene of an allylic alcohol and initiate ensuing ring‐expansion of cyclopropanol or cyclobutanol. This tandem reaction enables the production of a wide range of nonracemic functionalizable α‐quaternary‐δ‐carbonyl cycloketones in high yields and excellent enantioselectivity from simple aldehydes and allylic alcohols. As a key step, the intramolecular reaction was also successfully applied in the asymmetric total synthesis of (+)‐cerapicol.

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An Enantioselective Synthesis of the ABD Tricycle for (−)‐Phomactin A Featuring Rawal’s Asymmetric Diels–Alder Cycloaddition

Abstract: An enantioselective synthesis of the ABD-ring of (−)-phomactin A is described here. The sequence features Rawal’s asymmetric Diels-Alder cycloaddition. The overall length is significantly reduced from our previous attempt.

Cited by 29 publications

References 80 publications

Total Syntheses of Scaparvins B, C, and D Enabled by a Key C–H Functionalization

Total Syntheses of Scaparvins B, C, and D Enabled by a Key C–H Functionalization

Synthesis of tetrasubstituted 1-silyloxy-3-aminobutadienes and chemistry beyond Diels–Alder reactions

Enantioselective Catalytic Aldehyde α‐Alkylation/Semipinacol Rearrangement: Construction of α‐Quaternary‐δ‐Carbonyl Cycloketones and Total Synthesis of (+)‐Cerapicol

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