Synthesis of 2-Substituted 3,5-Dibromothiophenes via a Rearrangement Reaction: A New Example of a Base-Catalyzed Halogen Dance Reaction

Sauter, F.; Fröhlich, Hannes; Kalt, Wolfram

doi:10.1055/s-1989-27391

Cited by 29 publications

(7 citation statements)

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“…14 The same substitution pattern can also be obtained starting from 2,3-dibromothiophene 31, which upon lithiation with LDA rearranges to 35, as well (Scheme 8). 16 Taylor then showed that the modalities of reagent addition can determine whether an HD reaction takes place or is prevented. 17 5-Bromo-4-(methylthio)thiophene-2-carboxylic acid 42 was formed exclusively when 2-bromo-3-(methylthio)thiophene 41 was added slowly to an excess of LDA at 278 uC (followed by addition of CO 2 ).…”

Section: 21mentioning

confidence: 99%

Halogen dance reactions—A review

et al. 2007

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Halogen Dance (HD) reactions are a useful tool for synthetic chemists as they enable access to positions in aromatic and heteroaromatic systems for subsequent functionalization which are often difficult to address by other methods, hence, allowing entry to versatile scaffolds. While the method can be extremely useful, this transformation is often neglected upon designing synthetic sequences. This may be largely attributed to the lack of comprehensive reference works covering the general principles and outlining the versatility and limitations of the technique. The following review tries to present HD reactions in a clear and concise manner in order to convince more chemists of its advantages. It covers the field of HD reactions from their first observation in 1951 until the present. The important contributions leading to the elucidation of the mechanism are briefly outlined followed by a detailed mechanistic section and a discussion of factors which influence HD reactions. Finally, an overview of HD reactions on various carbocyclic and heterocyclic ring systems and its applications in the synthesis of complex compounds is given.

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Section: 21mentioning

confidence: 99%

Halogen dance reactions—A review

et al. 2007

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“…The driving force for this reaction is the formation of a more stable organolithium, and typically, the added stability is derived from having the lithium flanked by the halogen and an additional carbanion stabilizing group. However, this is not a required component of the reaction; if a substrate contains sites that differ in acidity, there exists a thermodynamic driving force for the rearrangement of a lithio species to the more acidic site …”

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confidence: 99%

Use of Thiazoles in the Halogen Dance Reaction: Application to the Total Synthesis of WS75624 B

Stangeland

Sammakia

2004

J. Org. Chem.

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The total synthesis of the pyridine-thiazole-containing natural product WS75624 B (1) is described. This synthesis proceeds via the Stille coupling of appropriately functionalized pyridine and thiazole components, and this paper details our studies on the use of the halogen dance reaction to prepare the desired thiazole. Various halogen dance reactions on thizoles are described, including a novel one-pot multistep reaction in which 2-bromothiazole is treated with LDA in the presence of a silyl chloride at -78 degrees C and quenched with an electrophile to provide the highly functionalized thiazole derivatives 27.

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“…[19] Finally, Li/I exchange at low temperatures and the subsequent nucleophilic substitution onto the perfluorocyclopentene eventually afforded precursor 3 in excellent yields. [20] In the meantime, a "halogen dance" reaction [21] on 2,5-dibromothiophene afforded 4 in excellent yield. Li/Br exchange followed by a substitution onto TMSCl or TiPSCl resulted in obtaining derivatives 5a or 5b in 72 % yields.…”

Section: Synthesesmentioning

confidence: 99%

Enhanced Photochemical Sensitivity in Photochromic Diarylethenes Based on a Benzothiophene/Thiophene Nonsymmetrical Structure

et al. 2014

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Photosensitivity of molecules is one of the central subjects of organic photochemistry. In this article, we present how and why a benzothiophene moiety impacts the photochromic quantum yield for the photochemical pericyclic ring closing of the hexatriene moiety. Two compounds were prepared: a symmetrical one incorporating two fluorenylthiophene units, and its corresponding nonsymmetrical partner, where one of the thiophene units was replaced by a benzothiophene group. Interestingly, the latter presents relatively high cyclization quantum yield (0.74), a value close to the largest one so far reported. Based on crystal structures, VT‐NMR data and DFT calculations, we demonstrate that introducing a benzothiophene in the molecular scaffold induces skeleton stiffening by means of CH–π interactions and steric repulsions, and leads to increased population of the reactive conformer in the ambient conditions.

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Synthesis of 2-Substituted 3,5-Dibromothiophenes via a Rearrangement Reaction: A New Example of a Base-Catalyzed Halogen Dance Reaction

Cited by 29 publications

References 0 publications

Halogen dance reactions—A review

Halogen dance reactions—A review

Use of Thiazoles in the Halogen Dance Reaction: Application to the Total Synthesis of WS75624 B

Enhanced Photochemical Sensitivity in Photochromic Diarylethenes Based on a Benzothiophene/Thiophene Nonsymmetrical Structure

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