Divergent Approach to Gabosines and Anhydrogabosines: Enantioselective Syntheses of (+)‐Epiepoformin, (+)‐EpoKformin, (+)‐Gabosine A, and Gabosines B and F

Toribio, Gladis; Marjanet, Georgina; Alibés, Ramón; March, Pedro de; Font, Josep; Bayón, Pau; Figueredo, Marta

doi:10.1002/ejoc.201001527

Cited by 29 publications

(30 citation statements)

References 59 publications

(35 reference statements)

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“…Using tert ‐butyl hydrogen peroxide, the epoxidation exclusively took place (dr > 10:1) on the opposite face with respect to the OTBS group. Observations for similar substrates with comparable stereochemical outcome have already been described in the literature . Although the obtained selectivities cannot be fully explained based on steric or stereoelectronic effects or both, it might be reasonable to argue that the attack for the sterically more demanding tert ‐butyl hydrogen peroxide preferably takes place from the less shielded face of the six‐membered ring at C(2) of 4 with the OTBS group in a pseudoequatorial position.…”

Section: Resultssupporting

confidence: 55%

Total Synthesis of the Polyoxygenated Sesquiterpenes Guignarderemophilanes C and D

Ilazi

Liffert

Gademann

2018

Helvetica Chimica Acta

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The total syntheses of the neural anti‐inflammatory agents guignarderemophilanes C and D have been accomplished for the first time starting from γ‐hydroxy carvone in 15 and 14 steps, respectively. The presented synthetic route proceeds via a known intermediate, whose synthesis has been elaborated in our group in the course of the total synthesis of the sesquiterpenoid periconianone A. Key for the successful conversion of this intermediate into both targets was finding a suitable strategy to install the 1,2,3‐trihydroxylated A‐ring scaffold. For this purpose, we effectively employed a Mitsunobu inversion, epoxidation, and regioselective epoxide opening sequence, before the bicyclic ring system was constructed by an aldol condensation reaction on a sterically demanding substrate. Our reported synthesis set the stage for SAR studies to prepare even more potent compounds by modification and derivatization of the natural product's scaffold.

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Section: Resultssupporting

confidence: 55%

Total Synthesis of the Polyoxygenated Sesquiterpenes Guignarderemophilanes C and D

Ilazi

Liffert

Gademann

2018

Helvetica Chimica Acta

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“…Finally, C–S bonds are relatively weak, and a variety of mild, operationally facile methods for their cleavage have been utilized in the synthesis of complex molecules. 12 We imagined that successful development of this sequence would enable the preparation of formal cycloaddition products of simple alkenes that are not amenable to direct activation by photoredox catalysis and would also be challenging to engage in classical thermal cycloaddition methods.…”

mentioning

confidence: 99%

Radical Cation Cycloadditions Using Cleavable Redox Auxiliaries

et al. 2016

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The incorporation of an easily oxidized arylsulfide moiety facilitates the photocatalytic generation of alkene radical cations that undergo a variety of cycloaddition reactions with electron-rich reaction partners. The sulfide moiety can subsequently be reductively cleaved in a traceless fashion, affording products that are not otherwise directly accessible using photoredox catalysis. This approach constitutes a novel oxidative “redox auxiliary” strategy that offers a practical means to circumvent a fundamental thermodynamic limitation facing photoredox reactions.

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“…Removal of the protective groups permitted to achieve the total synthesis of (+)-theobroxide (ent-21 (+)-Epiepoformin (2) and (+)-epoformin (1) have been synthesized [90] using chiral hydroxyenones obtained by lipase resolution in a previous work of the authors [91]. Double elimination of bromide, followed by photosensitized oxidation and reduction of the non-isolated endoperoxide yielded the racemic 21.…”

Section: Use Of Lipase-mediated Kinetic Resolutionsmentioning

confidence: 99%

Enantioselective Synthesis of Natural Epoxyquinoids

Pandolfi

Schapiro²,

Heguaburu³

et al. 2013

COS

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Natural products play an important role as a source not only of potential therapeutic drugs but also of starting materials for semisynthetic new medicines. The epoxyquinoid family, composed by cyclohexane epoxides and related structures, exhibit these characteristics without doubt.Since 2004, significant efforts have been devoted to the stereocontrolled synthesis of these molecules with different and interesting strategies. More than 50 works on this field have been published during this period of time. In addition, many of these polyoxygenated cyclohexenoids exhibit diverse and impressive bioactive shapes. This review aims to analyze the recent advances in the enantioselective processes that have been performed for the total syntheses of these target molecules. It includes a wide range of methodologies for the introduction of chirality either enzymatic or chemical ones. This summarizes microbial preparation of starting materials, lipase kinetic resolutions, use of compounds from the chiral pool, use of chiral auxiliaries and asymmetric catalysis. In a special section, syntheses of scyphostatin are also included.

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Divergent Approach to Gabosines and Anhydrogabosines: Enantioselective Syntheses of (+)‐Epiepoformin, (+)‐EpoKformin, (+)‐Gabosine A, and Gabosines B and F

Cited by 29 publications

References 59 publications

Total Synthesis of the Polyoxygenated Sesquiterpenes Guignarderemophilanes C and D

Total Synthesis of the Polyoxygenated Sesquiterpenes Guignarderemophilanes C and D

Radical Cation Cycloadditions Using Cleavable Redox Auxiliaries

Enantioselective Synthesis of Natural Epoxyquinoids

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