Asymmetric Synthesis of All Stereoisomers of Isofagomine Using [2,3]-Wittig Rearrangement

Takahata, Hiroki; Mihara, Yukiko; Ojima, Hidetomo; Imahori, Tatsushi; Yoshimura, Yuichi; Ouchi, Hidekazu

doi:10.3987/com-07-s(k)58

Cited by 22 publications

(13 citation statements)

References 47 publications

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“…The use of hexanes enhanced the overall conversion, but the distribution of products was not improved compared to THF (Scheme B, entry 11 vs. entry 4). A positive effect of hexane on the selectivity profile was reported in several cases of the Wittig–Still rearrangement used in the synthesis of natural products; such examples will be discussed in Section 7.1 …”

Section: General Considerationsmentioning

confidence: 99%

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Applications of the Wittig–Still Rearrangement in Organic Synthesis

Rýček

Hudlický

2017

Angew Chem Int Ed

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This Review traces the discovery of the Wittig-Still rearrangement and its applications in organic synthesis. Its relationship to Wittig rearrangements is discussed along with detailed analysis of E/Z- and diastereoselectivity. Modifications of the products arising from the Wittig-Still rearrangement are reviewed in the context of increased complexity in intermediates potentially useful in target-oriented synthesis. Early applications of the Wittig-Still rearrangement to modifications of steroids are reviewed as are applications to various terpene and alkaloid natural product targets and miscellaneous compounds. To the best of our knowledge, the literature is covered through December 2016.

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Section: General Considerationsmentioning

confidence: 99%

“… Takahata's synthesis of four stereoisomers of an azasugar isofagomine ( 409 ) from the common intermediate 413 …”

Section: Miscellaneous Compoundsmentioning

confidence: 99%

Applications of the Wittig–Still Rearrangement in Organic Synthesis

Rýček

Hudlický

2017

Angew Chem Int Ed

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“… Takahatas Synthese von vier Stereoisomeren des Azazuckers Isofagomin ( 409 ) aus einem gemeinsamen Intermediat 413 …”

Section: Sonstige Verbindungenunclassified

“…Ein positiver Einfluss von Hexan auf das Selektivitätsprofil wurde für einige Anwendungen der Wittig-Still-Umlagerung in der Synthese von Naturstoffen berichtet;solche Beispiele werden in Abschnitt 7.1 diskutiert. [28][29][30][31][32] Brückner verglich Cohens Methode zur Erzeugung der anionischen Vorstufen fürdie Wittig-Umlagerung mit dem in der Wittig-Still-Version verwendeten Vorgehen.…”

Section: Allgemeine üBerlegungenunclassified

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Anwendungen der Wittig‐Still‐Umlagerung in der organischen Synthese

Rýček

Hudlický

2017

Angewandte Chemie

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Dieser Aufsatz zeichnet die Entstehung der Wittig‐Still‐Umlagerung und deren Anwendung in der organischen Synthese nach. Ihre Beziehung zur Wittig‐Umlagerung wird diskutiert, einhergehend mit einer detaillierten Analyse der E/Z‐Selektivität und Diastereoselektivität. Modifikationen der in Wittig‐Still‐Umlagerungen gebildeten Produkte werden im Zusammenhang der gesteigerten Komplexität von Intermediaten mit potenziellem Nutzen für die zielorientierte Synthese erläutert. Frühe Anwendungen der Wittig‐Still‐Umlagerung zur Modifizierung von Steroiden werden ebenso besprochen wie Anwendungen in der Naturstoffsynthesen von Alkaloiden und Terpenen sowie der Synthese sonstiger Verbindungen. Nach unserem besten Wissen ist die Literatur bis Dezember 2016 abgedeckt.

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[2,3]‐Wittig Rearrangement

2010

Comprehensive Organic Name Reactions and Reagents

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This reaction is a highly regioselective [2,3]‐sigmatropic rearrangement of the conjugate bases of allylic ethers (or benzylic ethers) to alcohols with concomitant C‐C bond formation. Therefore, this type of anionic [2,3]‐sigmatropic rearrangement is generally known as the [2,3]‐Wittig rearrangement. This rearrangement has been extended to α‐alkoxystannes and is referred to as the Still–Wittig [2,3]‐sigmatropic rearrangement. Analogously, the rearrangement of silyl anion from a silyl allylic ether is termed as the siloxy ‐[2,3] Wittig rearrangement and the rearrangement of an allylic amine in the presence of a strong base is called the aza ‐2,3‐Wittig rearrangement. The driving force for this rearrangement is probably the conversion of a moderately stabilized carbanion to a more stable alkoxide. It has been proposed that the breaking C‐O bond and the forming C‐C bond in the transition state are almost eclipsed, and the steric effect and electronic interaction at this point result in a high stereoselectivity. All the mechanistic features of the reaction have been discussed and it has been found that the tertiary bis ‐allyl ethers do not undergo the [2,3]‐Wittig rearrangement when treated with butyl lithium, but proceeds readily when treated with the combination of t ‐BuOK and t ‐BuLi. For the tertiary bis ‐allyl ether derived from (+)‐camphor, the rearrangement occurs via an endo ‐transition state to afford products of R ‐configuration. On the other hand, the substituent at either α‐ or γ‐position of the allylic moiety will depress the lithiation. In the case of 3‐furylmethyl ethers, the [2,3]‐Wittig rearrangement is indeed competed with [1,2]‐Wittig rearrangement, and the actual outcome depends on the bases applied. Overall, the [2,3]‐Wittig rearrangement is very common and widely used in organic synthesis.

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Asymmetric Synthesis of All Stereoisomers of Isofagomine Using [2,3]-Wittig Rearrangement

Cited by 22 publications

References 47 publications

Applications of the Wittig–Still Rearrangement in Organic Synthesis

Applications of the Wittig–Still Rearrangement in Organic Synthesis

Anwendungen der Wittig‐Still‐Umlagerung in der organischen Synthese

[2,3]‐Wittig Rearrangement

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