Enantioselective Total Synthesis of Shahamin K

Lebsack, Alec D.; Overman, Larry E.; Valentekovich, Robert J.

doi:10.1021/ja015802o

Cited by 85 publications

(38 citation statements)

References 19 publications

(12 reference statements)

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“…Representative examples of carbocyclic ring systems that can be prepared in this fashion, typically with high stereoselectivity, are shown in Scheme 18. One useful expression of this chemistry couples carbocyclic ring formation with expansion of a starting ring by one-carbon (e.g., formation of 89 – 91, 93 and 94 ) 100–104. Although we have generally employed an acetal as the precursor to an oxocarbenium ion intermediate, the initial cationic cyclization is brought about more selectively with a thiocarbenium ion (e.g., formation of 94 ) 104,105.…”

Section: Pinacol-terminated Cationic Cyclization Reactionsmentioning

confidence: 99%

Molecular rearrangements in the construction of complex molecules

Overman

2009

Tetrahedron

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Section: Pinacol-terminated Cationic Cyclization Reactionsmentioning

confidence: 99%

Molecular rearrangements in the construction of complex molecules

Overman

2009

Tetrahedron

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“…1 In 2001 we disclosed the first total synthesis of a rearranged spongian diterpene, shahamin K ( 3 ), which possesses a cis -hydroazulene and a relatively simple monocyclic lactone subunit. 4 We recently demonstrated the first construction of the sensitive bicyclic lactone fragment of diterpenes 1 and 2 by the synthesis of simplified congeners 4 and 5 . 5 We report herein the enantioselective total synthesis of aplyviolene ( 1 ); the first total synthesis of a natural product containing a 6-acetoxy-2,7-dioxabicyclo[3.2.1]octan-3-one ring system.…”

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confidence: 99%

“…α-Bromoketone 7 was seen as a potential precursor of enoxysilane 6 . Compound 7 is recognizably the Michael-addition product of the thermodynamic enolate of hydroazulenone 8 4 and α-bromocyclopentenone 9 , with the proper relative configuration of the C8–C14 σ-bond expected to arise from the facial bias of the two enantioenriched coupling partners. Unknown at the onset was the compatibility of the exo -methylene functionality of the hydroazulene fragment with the oxidative and acidic steps that would be required to elaborate the bicyclic lactone subunit from precursor 6 .…”

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Enantioselective Total Synthesis of Aplyviolene

Schnermann

Overman

2011

J. Am. Chem. Soc.

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The enantioselective total synthesis of the rearranged spongian diterpene aplyviolene has been completed in 14 steps from the known hydroazulenone 8. The key junction of the hydrocarbon and oxygenated fragments to form the critical C8 quaternary carbon stereocenter and set the stage for elaborating the delicate bicyclic lactone functionality was accomplished in high yield and exquisite stereoselectivity by Michael addition of an enantioenriched hydroazulenone enolate to an enantiopure α-bromocyclopentenone.

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“…Shahamin K (6), which has an identical hydroazulene fragment, but a structurally simpler oxygenated fragment, was the initial rearranged spongian diterpene to be prepared by total synthesis (25).…”

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Golgi-modifying properties of macfarlandin E and the synthesis and evaluation of its 2,7-dioxabicyclo[3.2.1]octan-3-one core

Schnermann

Beaudry

Egorova

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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Golgi-modifying properties of the spongian diterpene macfarlandin E (MacE) and a synthetic analog, t-Bu-MacE, containing its 2,7-dioxabicyclo[3.2.1]octan-3-one moiety are reported. Natural product screening efforts identified MacE as inducing a novel morphological change in Golgi structure defined by ribbon fragmentation with maintenance of the resulting Golgi fragments in the pericentriolar region. t-Bu-MacE, which possesses the substituted 2,7-dioxabicyclo[3.2.1]octan-3-one but contains a tert-butyl group in place of the hydroazulene subunit of MacE, was prepared by chemical synthesis. Examination of the Golgi-modifying properties of MacE, t-Bu-MacE, and several related structures revealed that the entire oxygen-rich bridged-bicyclic fragment is required for induction of this unique Golgi organization phenotype. Further characterization of MacE-induced Golgi modification showed that protein secretion is inhibited, with no effect on the actin or microtubule cytoskeleton being observed. The conversion of t-Bu-MacE and a structurally related des-acetoxy congener to substituted pyrroles in the presence of primary amines in protic solvent at ambient temperatures suggests that covalent modification might be involved in the Golgi-altering activity of MacE.organelle organization | chemical biology | natural product | reactivity

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Enantioselective Total Synthesis of Shahamin K

Cited by 85 publications

References 19 publications

Molecular rearrangements in the construction of complex molecules

Molecular rearrangements in the construction of complex molecules

Enantioselective Total Synthesis of Aplyviolene

Golgi-modifying properties of macfarlandin E and the synthesis and evaluation of its 2,7-dioxabicyclo[3.2.1]octan-3-one core

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