A Stereoselective Cyclization to Carbafuranose Derivatives Starting from 1,4-Bis-epoxides

Leung, Leo; Boydell, A. James; Gibson, Vicky; Light, Mark E.; Linclau, Bruno

doi:10.1021/ol052009h

Cited by 15 publications

(6 citation statements)

References 38 publications

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“…Interestingly, 18 was obtained as a single diastereomer, but we were unable to determine its relative configuration. The relative configuration of 12b was proven by X-ray crystallographic analysis of its trityl derivative 17b . The same linchpin cyclization process starting from the C 2 -symmetric bis-epoxide 14 led to the desired carbafuranose derivative 11 .…”

Section: Resultsmentioning

confidence: 96%

“…The relative configuration of 12b was proven by X-ray crystallographic analysis of its trityl derivative 17b. 18 The same linchpin cyclization process starting from the C 2 -symmetric bis-epoxide 14 led to the desired carbafuranose derivative 11. Whereas on small scale only 11 was isolated (in 83%), a larger scale experiment permitted isolation of a very small amount of six-membered ring isomer 19 and of a protonated acyclic intermediate 20.…”

Section: Resultsmentioning

confidence: 99%

“…A summary of our results for the linchpin cyclization process is given in Scheme 2. 18 When the bis-epoxide 15 was used as a substrate, reaction with deprotonated 16 led to the desired 6′-benzyloxy epimers 12b and 12a in excellent combined yield (80%), together with a six-membered isomer 18. Interestingly, 18 was obtained as a single diastereomer, but we were unable to determine its relative configuration.…”

Section: Resultsmentioning

confidence: 99%

“…We have reported a short synthesis of carbafuranose derivatives 11 and 12 via a dithiane-based linchpin cyclization process starting from homochiral bis-epoxides such as 14 and 15 (Scheme ), of which both enantiomeric forms are equally available. It was envisioned that carbafuranose derivatives 11 / 12 , due to the relative anti -configuration of the 1′-OTBDMS and the 4′-hydroxymethyl group, would be suitable precursors for a convergent synthesis of carbanucleosides 9 , and that this would be a very convenient way to access 6′-substituted carbanucleosides which are interesting and topical targets .…”

Section: Introductionmentioning

confidence: 99%

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A Linchpin Carbacyclization Approach for the Synthesis of Carbanucleosides

2008

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A convenient synthesis of carbanucleosides, with both enantiomers equally accessible, is reported. The key step is a tandem linchpin cyclization process to give access to substituted carbafuranose derivatives having the correct relative stereochemistry for subsequent nucleobase introduction with inversion of configuration at C1. This was illustrated by the synthesis of 2',3'-dideoxycarbathymidine via a convergent nucleobase introduction and of 2',3'-dideoxy-6'-hydroxycarbauridine via a linear nucleobase introduction. Both methods relied on Mitsunobu chemistry, and the first example of the Mukaiyama modification of the Mitsunobu reaction involving nucleobases as nucleophiles is reported.

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Linchpin Carbacyclization Approach for the Synthesis of Carbanucleosides

2008

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“…65 Very recently, further successful applications of the reaction principle using bisepoxy-1,3-pentadienes were reported; the resulting cyclopentane derivatives are promising building blocks for carbanucleosides (Scheme 21). 67…”

Section: Scheme 19 a Bisepoxide As C 4 Building Blockmentioning

confidence: 99%

Domino Synthesis of Carbo- and Heterocycles Involving a 1,3 or 1,4 C→O Silyl Migration

Schaumann¹,

Kirschning²

2007

Synlett

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This account shows that a silyl-substituted carbanion may be looked upon as a latent dianion which, in the reaction with biselectrophiles, yields ring-closure products. The biselectrophile is normally an epoxide carrying a remote leaving group. The carbanion will open the epoxide and allow for a C→O silyl shift thus generating the new carbanion. This then reacts with the second functional group of the biselectrophile. The flexibility of the approach is demonstrated by using various acceptor groups on the initial carbanion 1 (SR, SiR 3 , CN) while the range of biselectrophiles includes epoxyalkyl tosylates, bisepoxides, epoxy-aziridines, vinylepoxides, and, for heterocyclic synthesis, bromoalkyl isocyanates. Instead of the epoxide, an ester group may act as electrophile. 7Bromoalkyl Isocyanates as Biselectrophiles 8Divertimento! 9 Conclusion

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The Brook Rearrangement

Yang

et al. 2020

Organic Reactions

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The Brook rearrangement describes the intramolecular silyl group migration from a carbon to an oxygen atom in a “through‐space” fashion. This feature has been extensively applied to develop numerous useful transformations of diverse organosilanes. Some representative examples include formal [3 + 2] and [4 + 3] annulations to construct diverse ring systems, syntheses of configurationally defined silyl enol ethers, multi‐component reactions by Brook rearrangement‐based ARC (anion relay chemistry), and various umpolung processes such as silyl benzoin condensations and sila‐Stetter reactions. This chapter presents a thorough overview of the Brook rearrangement. The scope and limitations are categorized according to the organosilane type. The mechanism and stereochemical course of this process are discussed, as is its application in the synthesis of complex natural products. The literature is covered up to the end of 2019.

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A Stereoselective Cyclization to Carbafuranose Derivatives Starting from 1,4-Bis-epoxides

Abstract: [reactions: see text] A concise synthesis of highly functionalized cyclopentane derivatives via a Brook rearrangement mediated stereoselective linchpin cyclization reaction involving tert-butyldimethylsilyl-1,3-dithianyllithium and homochiral 1,4-bis-epoxides is described.

Cited by 15 publications

References 38 publications

A Linchpin Carbacyclization Approach for the Synthesis of Carbanucleosides

A Linchpin Carbacyclization Approach for the Synthesis of Carbanucleosides

Domino Synthesis of Carbo- and Heterocycles Involving a 1,3 or 1,4 C→O Silyl Migration

The Brook Rearrangement

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