Synthesis of the ABC Fragment of the Pectenotoxins

Halim, Rosliana; Brimble, Margaret A.; Merten, Jörn

doi:10.1021/ol0507975

Cited by 43 publications

(8 citation statements)

References 27 publications

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“…The solution of the latter two challenges employed a common reaction sequence including a coupling reaction between sulfone and aldehyde segments, oxidation of the resulting β‐hydroxy sulfone to an α‐sulfonylketone, reductive desulfonylation, and spirocyclic/bicyclic acetal formation. The reliability of the sequence to form the anomeric spiroacetal was previously demonstrated by Brimble and co‐workers in the synthetic studies of PTXs 12e. Therefore, we employed the sequence for the assembly of 3 from aldehyde 4 13c and sulfone 5 .…”

Section: Methodsmentioning

confidence: 86%

Total Synthesis of Pectenotoxin‐2

et al. 2013

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Pectenotoxin‐2 (PTX2) is a shellfish toxin and has a non‐anomeric spiroacetal, which is not stabilized by an anomeric effect. The selective construction of the non‐anomeric spiroacetal has been a major problem in the synthesis of PTX2. Described herein is the stereoselective total synthesis of PTX2 via the isomerization of anomeric spiroacetal pectenotoxin‐2b (PTX2b). The synthesis of PTX2b was achieved by a simple process including sulfone‐mediated assembly of spirocyclic and bicyclic acetals and subsequent macrocyclization by ring‐closing olefin metathesis. Finally, the selective construction of PTX2 was accomplished by the early termination of a dynamic transition process to equilibrium in the acid‐catalyzed isomerization of anomeric PTX2b. [6,6]‐Spiroacetal pectenotoxin‐2c (PTX2c) was also synthesized from PTX2b. The cytotoxicity assay of the synthetic compounds against HepG2 and Caco2 cancer cells showed a potency of the order: PTX2≫PTX2b>PTX2c.

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Section: Methodsmentioning

confidence: 86%

Total Synthesis of Pectenotoxin‐2

et al. 2013

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“…Brimble and co-workers demonstrated the epoxidation of a mixture of (Z)-and (E)-enynes (204 + 205) during the synthesis of the ABC tricyclic part of pectenotoxins (Scheme 58). [240,241] The mixture upon treatment with m-CPBA and DMDO (ACD-3) led to syn-and anti-epoxides, i. e., 206 and 207, in 1.2 : 1 and 1.8 : 1 ratio, respectively. When the oxidation was performed with chiral ketones derived from D-and L-fructose, the syn-and antiepoxides were produced in 1 : 8 and 5.5 : 1 ratios, respectively.…”

Section: Peptide-derived Ketone Precatalysts For Epoxidationsmentioning

confidence: 99%

Dioxirane‐Based Stereoselective and Oxidative Transformations

Neogi,

Parida

2024

ChemistrySelect

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The synthesis of chiral organic molecules is a purity‐driven research that has become an essential part of our lives due to their applications in pharmaceuticals. Contemporary research focuses on the exploration of synthetic protocols that obviate the use/generation of hazardous chemicals. In this regard, dioxiranes are readily accessed as a reagent solution or catalyst (in situ) from the reaction of ketone with a co‐oxidant like Oxone® or H2O2; the latter makes the protocol very green and inexpensive. It has shown the potential to replace transition metal‐based oxygenation protocols. The dioxirane‐mediated asymmetric reactions include oxidations, epoxidations, C−H hydroxylations, etc. Both stoichiometric and catalytic protocols of dioxiranes are been explored for the oxyfunctionalization of chiral natural product derivatives such as Penicillin, nucleosides, amino acids, carbohydrates, etc. In addition, these are employed as key oxygenation agents during the synthesis of natural products like (+)‐Plagiogyrin A, Portimine, Taxol, Bryostatin, dafachronic acid, majucinoids, eldecalcitol, Spirochensilide A, etc. The review consolidates the development of both achiral and chiral dioxiranes in application to asymmetric synthesis and oxygenation of chiral molecules.

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“…Shortly after Paquette and co-workers published their synthesis of the C1-C26 fragment of PTX2 in 2005, 37 we disclosed our approach towards the C1-C16 ABC spiroacetal containing subunit 105. 47,48 Our strategy hinged on initial formation of the C1-C11 AB spiroacetal fragment 100. In a similar manner to that observed by Paquette, we also formed the 7S-spiroacetal centre as opposed to the required 7R in natural PTX2 (Scheme 12).…”

Section: Brimble's Approach To Ptx2mentioning

confidence: 99%

Synthetic studies towards the pectenotoxins: a review

Halim

Brimble

2006

Org. Biomol. Chem.

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In this article we provide an overview of synthetic studies towards pectenotoxins (PTXs) that have been reported by several research groups. The difficulties encountered in the synthesis of these series of polyketides are highlighted by the fact that only one total synthesis of PTX4 and PTX8 has been completed to date. The strategies used in the critical bond forming steps and the introduction of key stereogenic centres are compared and contrasted.

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Synthesis of the ABC Fragment of the Pectenotoxins

Cited by 43 publications

References 27 publications

Total Synthesis of Pectenotoxin‐2

Total Synthesis of Pectenotoxin‐2

Dioxirane‐Based Stereoselective and Oxidative Transformations

Synthetic studies towards the pectenotoxins: a review

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