Formal Halo‐Meyer–Schuster Rearrangement of Propargylic Acetates through a Novel Intermediate and an Unexampled Mechanistic Pathway

Most of this review article has been prepared during Covid 19 pandemy. Therefore, we dedicate it,-first to all persons who unfortunately died from this disease and,-second to all people (medical doctors and many others) who helped their congeners to survive to this pandemy. The Meyer-Schuster rearrangement is an efficient method to prepare α,β-unsatured carbonyl compounds starting from propargylic alcohols and this review presents the remarkable progress made during the last decade in this reaction. New efficient catalytic systems have been discovered and many elegant applications have been reported for this rearrangement. To be noticed in particular are the new and efficient cascade processes affording a wide range of carbo-and heterocyclic molecules. Moreover, brilliant applications of this rearrangement have been described as well, in the total synthesis of complex natural products and their analogues. Finally, the first examples of aza-Meyer-Schuster rearrangements have been recently described as well.

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“…Another possibility to prepare α‐halo enones has been reported starting from propargylic acetates 50 (Scheme 11). [50a] …”

Section: New Catalytic Systems Leading To αβ‐Unsaturated Carbonyl Dementioning

confidence: 99%

Recent Developments in the Meyer‐Schuster Rearrangement

Justaud¹,

Hachem

Grée³

2021

Eur J Org Chem

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“…On the other hand, α‐I‐chalcone was allowed to react with phenylacetylene performing Sonogashira coupling; the product was treated with AgNO 3 and N ‐Me‐aniline at room temperature to give a trisubstituted furan derivative (reaction 3, Figure 51). [176] Reaction 4, Figure 51 shows that α‐I‐chalcone can be prepared from α‐unsubstituted chalcone using ICl and triethylamine. The produced α‐I‐chalcone was converted to 11 H ‐indeno[1,2‐b]quinolin‐11‐ones using sun lamp and hexamethylditin (Me 3 Sn) 2 at 80 °C [204]…”

Section: Different α‐Substituted Chalconesmentioning

confidence: 99%

“…The prepared chalcones were allowed to react with p ‐methoxyphenol to afford the α‐aryloxychalcone as a mixture of E and Z isomers. Recently, a highly stereoselective halo‐Meyer‐Schuster rearrangement of inactivated propargylic acetates to ( Z )‐α‐haloenones, including chalcones, has been reported [176] . This method uses N ‐halosuccinimide (NXS) reagents (reaction 4, Figure 46).…”

Section: Different α‐Substituted Chalconesmentioning

confidence: 99%

α‐Substituted Chalcones: A Key Review

Al-Rifai

Mubarak

2021

ChemistrySelect

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Chalcones are attractive chemical motifs with various biological activities. Aryl substituted chalcones have been extensively studied and reviewed through the years. However, α‐substituted chalcones have rarely been investigated. Hence, this review highlights the α‐substituted chalcones: their synthetic routes, reported biological activities, and transformations to other organic compounds. To the best of our knowledge, this would be the first comprehensive review about α‐substituted chalcones. α‐Substitution of chalcones represents a promising approach to tune their reactivity since it has a direct influence on their activity as Michael acceptors. Additionally, α‐substitution has its effect on the structure and conformation of chalcones. Altering the reactivity of chalcones by α‐substitution has a great impact on their biological activity.

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“…In this context, in 2017 our research group, also developed a metal‐free strategy for the synthesis of α,α‐dihalo‐α′‐acetoxyketones 26 from propargylic acetates 27 (Table , entry 2) and NXS reagents . Recently, we have also reported the regioselective synthesis of α,α‐dihalo‐β‐acetoxyketones 28 from internal propargylic acetates 29 upon treatment with N ‐halosuccinimide in hot acetonitrile and water (1:1) …”

Section: Synthetic Approaches To αα‐Dihaloketonesmentioning

confidence: 99%

“…Recently, our research group has synthesized another new class of gem ‐dihaloketones, that is,α,α‐dihalo‐β‐acetoxyketones 202 a starting from inactivated internal propargylic acetates 202 using NXS and CH 3 CN, water as solvents. This in situ generated α,α‐dihaloketones 202 a upon treatment with Lewis basic water (continuous heating of reaction mixture) generated α‐haloenones 203 via an E1cB mechanism (Scheme ).…”

Section: In Situ Generation and Further Reactivity Of Gem‐dihalocarbomentioning

confidence: 99%

The α,α‐Dihalocarbonyl Building Blocks: An Avenue for New Reaction Development in Organic Synthesis

Sadhukhan

Santhi

Baire

2020

Chemistry A European J

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The α,α‐dihalocarbonyl moiety is a bifunctional system with a gem‐dihalocarbon and a carbonyl carbon in 1,2‐fashion. This is one of the privileged scaffolds in medicinal chemistry due to its chemical and metabolic stability and lipophilicity. They have also been found in numerous structurally divergent natural products and most of their fabricated structures have already been in medicinal use. Apart from their important use in medicinal chemistry, the α,α‐dihalocarbonyl groups have been employed as key building blocks for the development of novel synthetic strategies and utilized as intermediates in total synthesis. In addition to the traditional transformations such as oxidations, reductions, and C−C bond formations, recently several new and non‐classical reactions have also been developed. This review provides short description of existing methods for their synthesis and detailed discussion on the efforts for the discovery and development of new reactions by employing α,α‐dihaloketones as synthetic building blocks. We have presented their use as key functional groups for the synthesis of polycyclic systems of medicinal and material importance and natural products.

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Formal Halo‐Meyer–Schuster Rearrangement of Propargylic Acetates through a Novel Intermediate and an Unexampled Mechanistic Pathway

Cited by 18 publications

References 54 publications

Recent Developments in the Meyer‐Schuster Rearrangement

Recent Developments in the Meyer‐Schuster Rearrangement

α‐Substituted Chalcones: A Key Review

The α,α‐Dihalocarbonyl Building Blocks: An Avenue for New Reaction Development in Organic Synthesis

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