The Mislow–Evans Rearrangement

Rojas, Christian M.

doi:10.1002/9781118939901.ch18

Cited by 50 publications

(50 citation statements)

References 101 publications

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“…Firstly, vinyl halide 17 was synthesized from 20 via Mislow-Evans [2,3] rearrangement: bisguanidine 20 was converted to N,S-acetal 21 by reaction with benzenethiol in the presence of BF 3 •Et 2 O with 84% yield. Upon treatment of 21 with urea-hydrogen peroxide (UHP), the Mislow-Evans [2,3] rearrangement reaction [88,89] took place under heating in the presence of sodium benzenthiolate, and allylic alcohol 23 was obtained with 81% yield in two steps. After oxidation of the alcohol with Dess-Martin periodinate, the resulting enone 24 was reacted with iodine in the presence of pyridine to give vinyl iodide 17 [90,91], which was further elaborated to 19 by Stille coupling reaction with 25 with 60% yield.…”

Section: Carbon-carbon Bond Formation At C11 By Stille Coupling Reactmentioning

confidence: 99%

“…This issue was successfully overcome by switching from CuI to copper(I) thiophene-2-carboxylate (CuTC), and 19 was obtained with 60% yield and with good reproducibility (entry 6) [87]. [88,89] took place under heating in the presence of sodium benzenthiolate, and allylic alcohol 23 was obtained with 81% yield in two steps. After oxidation of the alcohol with Dess-Martin periodinate, the resulting enone 24 was reacted with iodine in the presence of pyridine to give vinyl iodide 17 [90,91], which was further elaborated to 19 by Stille coupling reaction with 25 with 60% yield.…”

Section: Carbon-carbon Bond Formation At C11 By C-alkylation As Applmentioning

confidence: 99%

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Synthetic Approaches to Zetekitoxin AB, a Potent Voltage-Gated Sodium Channel Inhibitor

et al. 2019

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Voltage-gated sodium channels (NaVs) are membrane proteins that are involved in the generation and propagation of action potentials in neurons. Recently, the structure of a complex made of a tetrodotoxin-sensitive (TTX-s) NaV subtype with saxitoxin (STX), a shellfish toxin, was determined. STX potently inhibits TTX-s NaV, and is used as a biological tool to investigate the function of NaVs. More than 50 analogs of STX have been isolated from nature. Among them, zetekitoxin AB (ZTX) has a distinctive chemical structure, and is the most potent inhibitor of NaVs, including tetrodotoxin-resistant (TTX-r) NaV. Despite intensive synthetic studies, total synthesis of ZTX has not yet been achieved. Here, we review recent efforts directed toward the total synthesis of ZTX, including syntheses of 11-saxitoxinethanoic acid (SEA), which is considered a useful synthetic model for ZTX, since it contains a key carbon–carbon bond at the C11 position.

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Section: Carbon-carbon Bond Formation At C11 By Stille Coupling Reactmentioning

confidence: 99%

Section: Carbon-carbon Bond Formation At C11 By C-alkylation As Applmentioning

confidence: 99%

Synthetic Approaches to Zetekitoxin AB, a Potent Voltage-Gated Sodium Channel Inhibitor

et al. 2019

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“…Similar to the aesthetically pleasing Kekulé’s dream of a snake biting its tail, molecular rearrangements have been appealing to chemists for a long time by virtue of their inherent elegance and unique glamour . Many synthetically useful applications enabled by rearrangements through chemical bond reorganization, including ring expansions (e.g., Beckmann rearrangement), ring contractions (e.g., the quasi-Favorskii rearrangement), functional group migrations (e.g., Smiles rearrangement), etc., manifest good atom- and step-economies.…”

Section: Introductionmentioning

confidence: 99%

Radical-Mediated Remote Functional Group Migration

Zhu

2020

Acc. Chem. Res.

242

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Metrics & MoreArticle Recommendations CONSPECTUS: Alkenes are ubiquitous in natural products and are extensively used as synthetic feedstocks in multiple fields including organic synthesis, medicinal chemistry, and materials science. Radical-mediated difunctionalization of alkenes provides a powerful tactic for alkene utilization. Despite the considerable progress made in the past several decades, state-of-the-art methods are highly dependent upon activated alkenes in which a proximal group with a π-electron system (e.g., aryl, carbonyl, and heteroatom) is requisite to stabilize the nascent alkyl radical intermediate via p−π conjugation or p orbitals of the heteroatom. In contrast, the transformation of unactivated alkenes, such as aliphatic alkenes, remains challenging.To overcome this obstacle, we have recently disclosed the strategy of intramolecular distal functional group migration (FGM), which has been efficiently applied in radical difunctionalization of unactivated alkenes. A portfolio of functional groups, such as cyano, heteroaryl, oximino, formyl, and alkynyl groups, showcase the excellent migratory aptitude. Mechanistically, after the addition of an extrinsic radical to the alkene, the newly formed active alkyl radical is rapidly captured by the intramolecular migratory group to generate a cyclic intermediate. Subsequent cleavage of the cyclic C−C bond of the intermediate leads to the functionalized product through the FGM process. Based on the strategy of FGM, a set of elusive difunctionalizations of unactivated alkenes have been accomplished (Part A). Alongside this research, an upgraded highly efficient synthetic strategy, "dock-migration," is created for intermolecular difunctionalization of alkenes. A diversity of sulfone-based dual-function reagents are developed. The intermolecular transformation is initiated by docking the dual-function reagent to the alkene, followed by intramolecular migration of the functional group.Compared to the original FGM protocol, the scope of alkenes is significantly extended from the strategically placed tertiary alcoholsubstituted alkenes to general alkenes. Both activated and unactivated alkenes are well tolerated. By this approach, radical-mediated fluoroalkylheteroarylation, fluoroalkylalkynylation, and alkylation of alkenes have been achieved (Part B). Direct elaboration of C−H bonds into the targeted functional groups represents one of the most ideal and straightforward methods for molecular functionalization. The FGM strategy proves to be an ingenious tool for radical-mediated functionalization of remote unactivated C(sp 3 )−H bonds. Based on the FGM process, we have accomplished: (a) remote C(sp 3 )−H heteroarylation and cyanation of unprotected alcohols via the cascade of alkoxy radical-enabled hydrogen atom transfer (HAT) and intramolecular functional group (e.g., heteroaryl, cyano) migration, and (b) distal C(sp 3 )−H vinylation of propargylic alcohols through consecutive alkenyl radical-promoted HAT process and subsequent alkenyl migration (Part C).

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“…Rearrangement reactions have attracted considerable interest over the past decades due to their high bond-forming efficiency and atom economy in the construction of complex organic architectures 20,21 . In contrast to the well-established [3,3]-rearrangement 22–25 , which generally proceeds via the chair-like transition state and thus is stereospecific (Figs.…”

Section: Introductionmentioning

confidence: 99%

Stereoselective synthesis of medium lactams enabled by metal-free hydroalkoxylation/stereospecific [1,3]-rearrangement

et al. 2019

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Rearrangement reactions have attracted considerable interest over the past decades due to their high bond-forming efficiency and atom economy in the construction of complex organic architectures. In contrast to the well-established [3,3]-rearrangement, [1,3] O-to-C rearrangement has been far less vigorously investigated, and stereospecific [1,3]-rearrangement is extremely rare. Here, we report a metal-free intramolecular hydroalkoxylation/[1,3]-rearrangement, leading to the practical and atom-economical assembly of various valuable medium-sized lactams with wide substrate scope and excellent diastereoselectivity. Moreover, such an asymmetric cascade cyclization has also been realized by chiral Brønsted acid-catalyzed kinetic resolution. In addition, biological tests reveal that some of these medium-sized lactams displayed their bioactivity as antitumor agents against melanoma cells, esophageal cancer cells and breast cancer cells. A mechanistic rationale for the reaction is further supported by control experiments and theoretical calculations.

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The Mislow–Evans Rearrangement

Cited by 50 publications

References 101 publications

Synthetic Approaches to Zetekitoxin AB, a Potent Voltage-Gated Sodium Channel Inhibitor

Synthetic Approaches to Zetekitoxin AB, a Potent Voltage-Gated Sodium Channel Inhibitor

Radical-Mediated Remote Functional Group Migration

Stereoselective synthesis of medium lactams enabled by metal-free hydroalkoxylation/stereospecific [1,3]-rearrangement

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