An Unexpected 2,3-Dihydrofuran Derivative Ring Opening Initiated by Electrophilic Bromination: Scope and Mechanistic Study

Zhao, Yi; Wong, Ying‐Chieh; Yeung, Ying‐Yeung

doi:10.1021/jo502453f

Cited by 12 publications

(4 citation statements)

References 40 publications

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“…The moisture present in the solvent plays an important role in opening the ring. 1940 NBS has been suitably treated in HF/pyridine to synthesize difluoroalkyl ethers from S,S,O-orthoesters. 1941 12.…”

Section: Ring-opening Reactionsmentioning

confidence: 99%

“…Recently, Yeung reported the ring opening of 2,3-dihydrofuran at the C-4–C-5 bond in the presence of the DABCO catalyst and NBS as the electrophilic halogen source. The moisture present in the solvent plays an important role in opening the ring . NBS has been suitably treated in HF/pyridine to synthesize difluoroalkyl ethers from S , S , O -orthoesters …”

Section: Ring-opening Reactionsmentioning

confidence: 99%

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Use of Bromine and Bromo-Organic Compounds in Organic Synthesis

2016

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Bromination is one of the most important transformations in organic synthesis and can be carried out using bromine and many other bromo compounds. Use of molecular bromine in organic synthesis is well-known. However, due to the hazardous nature of bromine, enormous growth has been witnessed in the past several decades for the development of solid bromine carriers. This review outlines the use of bromine and different bromo-organic compounds in organic synthesis. The applications of bromine, a total of 107 bromo-organic compounds, 11 other brominating agents, and a few natural bromine sources were incorporated. The scope of these reagents for various organic transformations such as bromination, cohalogenation, oxidation, cyclization, ring-opening reactions, substitution, rearrangement, hydrolysis, catalysis, etc. has been described briefly to highlight important aspects of the bromo-organic compounds in organic synthesis.

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Section: Ring-opening Reactionsmentioning

confidence: 99%

Section: Ring-opening Reactionsmentioning

confidence: 99%

Use of Bromine and Bromo-Organic Compounds in Organic Synthesis

2016

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“…To better understand the difference in reactivities of ketones 4 and esters 5 we carried out DFT calculations of energy barriers for C–C bond cleavage in hypothetical species I3 and I3′ (Scheme ) . These species can result from I2a (Scheme ) or 10a (Scheme ) by hydration of their dihydrofuran rings under acidic conditions.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Functionalized Quinolines from 4‐(o‐Nitroaryl)‐Substituted 3‐Acyl‐4,5‐Dihydrofurans: Reductive Cyclization and C=C Bond Cleavage

et al. 2017

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A new synthetic approach to functionalized quinolines was developed based on the application of Zn–AcOH system as a simple and efficient reductive agent towards 4‐(o‐nitroaryl)‐3‐acyl‐substituted 4,5‐dihydrofurans. Reduction of 3‐carbonyl‐substituted dihydrofurans is accomplished by C=C double‐bond cleavage in the dihydrofuran ring and 1,6‐cyclization, which leads to 3,4‐dihydroquinolines. The latter can be easily oxidized to quinolines or reduced to tetrahydroquinolines. For dihydrofuran‐3‐carboxylates, reduction proceeds with retention of the dihydrofuran ring and affords a tricyclic dihydrofuroquinoline core under harsher conditions. The proposed general reaction pattern was supported by results of DFT calculations. Moreover, a similar reductive system can be successfully applied in the conversion of dihydrofuran acyclic precursors, γ‐(o‐nitroaryl) α,β‐unsaturated carbonyl compounds, into quinoline derivatives.

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“…α-Allylation of 3b led to 7 in 78% yield with an extended chain, while selective mono- and dibromination of 3b gave 3d and 8 under different conditions. Reduction of 3b by DIBAL-H provided a pair of 4-acetyl THF diastereomers 9a (56%) and 9b (18%) as confirmed by XRD analysis, whereas reduction of 3b with HSiEt 3 in TFA gave the third diastereomer 9c in 61% yield …”

mentioning

confidence: 78%

Regio- and Stereospecific Hydrative Cloke–Wilson Rearrangement

Wang,

Wang

2023

Org. Lett.

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The Cloke−Wilson rearrangement of unsymmetrical βdiketone-derived cyclopropanes inevitably yields a mixture of two 4acylated 2,3-dihydrofuran regiomers. By using alkynes as masked acyls, Tf 2 NH-promoted Cloke−Wilson rearrangement of polysubstituted 1-(1alkynyl)cyclopropyl ketones followed by alkyne hydration is described, regioselectively affording 2,3-dihydrofurans bearing 4-acyls nonequivalent to that involved in the Cloke−Wilson rearrangement. The 2,3dihydrofuran rings with cis 2,3-diaryls are unexpectedly more stable than their trans diastereomers under the reaction conditions, guaranteeing the regiospecificity of this hydrative Cloke−Wilson rearrangement with high fidelity.

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An Unexpected 2,3-Dihydrofuran Derivative Ring Opening Initiated by Electrophilic Bromination: Scope and Mechanistic Study

Cited by 12 publications

References 40 publications

Use of Bromine and Bromo-Organic Compounds in Organic Synthesis

Use of Bromine and Bromo-Organic Compounds in Organic Synthesis

Synthesis of Functionalized Quinolines from 4‐(o‐Nitroaryl)‐Substituted 3‐Acyl‐4,5‐Dihydrofurans: Reductive Cyclization and C=C Bond Cleavage

Regio- and Stereospecific Hydrative Cloke–Wilson Rearrangement

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