The Truce–Smiles rearrangement and related reactions: a review

The use of TiCl3-HCl as promotor in the radical Truce-Smiles reactions of 2-(((3,5dimethylisoxazol-4-yl)sulfonyl)oxy)benzenediazonium salts has been investigated in detail. During these reactions the desired Truce-Smiles rearrangement (via an ipso-substitution reaction) is accompanied by the formation of a number of by-products including dihydrobenzo[5,6][1,2]oxathiino[3,4-d]isoxazole 4,4-dioxides, dioxidobenzo[e][1,2]oxathiin-3yl)ethan-1-ones, anilines and chloroaromatics. Replacing TiCl3-HCl by Cu(NO3)2-Cu2O as reductant in these reactions was found to afford broadly comparable product distributions. Competition and radical clock experiments also provide an indication of the relative susceptibility of the isoxazole nucleus towards attack by aryl radicals.

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“…Off-white crystalline solid. Yield (3aR*,11cR*)-3,11c-Dimethyl-3a,11cdihydronaphtho [1',2':5,6] [1,2]oxathiino [3,4-d]…”

Section: -(35-dimethylisoxazol-4-yl)naphthalen-2-ol 8cmentioning

confidence: 99%

“…1 The versatility of this reaction is due, in part, to the broad range of substrates that are found to participate in this transformation, which leads to the generation of new aryl C-C, C-O and C-N bonds (Scheme 1). 2…”

Section: Introductionmentioning

confidence: 99%

Radical Truce-Smiles reactions on an isoxazole template: Scope and limitations

et al. 2019

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“…In the Truce–Smiles rearrangement reaction ( Scheme 1 b), this is solved by generating a carbon nucleophile from the coupling group. 2 The original method involves deprotonation with strong bases like BuLi or KO t Bu, but in recent contributions, several alternative approaches have been presented that exploit carbanion equivalents, 3 carbenes, 4 or aryl/acyl radicals. 5 Among these approaches, Zeng et al present a remarkably convenient photoinduced reaction ( Scheme 1 a) that employs ultraviolet (UV) light without additional photocatalysts or the involvement of transition metals.…”

Section: Introductionmentioning

confidence: 99%

Density Functional Theory Evaluation of a Photoinduced Intramolecular Aryl Ether Rearrangement

Fehér

2021

J. Org. Chem.

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Recently, a new approach of converting (hetero)aryl ethers to C–C coupled products via a photoinduced intramolecular rearrangement has been reported. Although this reaction is photocatalyst-free, it requires excitation in the ultraviolet (UV) range. To help refine this process, three different 2-(hetero)aryloxybenzaldehydes are selected from the available substrate scope in which the general mechanism based on experimental results is evaluated using density functional theory calculations. The reaction takes place in the triplet state after photoexcitation and includes three main steps: the addition of carbonyl carbon to the ipso carbon of the aryl ether followed by the C–O cleavage of the resulting spirocyclic intermediates and then the transfer of the formyl proton to afford 2-hydroxybenzophenone-type products. This agrees with the experiments, but the calculated pathways show considerable differences between the three substrates. Above all, either the first or the second step can be rate-determining but not the C–H activation. The important factor behind the differences is the spin-density rearrangement, which is mainly responsible for the barrier of the ether cleavage. Based on the obtained insights, the strategy to improve the ∼250 nm excitation has been briefly discussed, and promising molecules are proposed to improve the scope of this process.

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“…A review of the literature indicates that the substrate scope of the Truce‐Smiles rearrangement is versatile, and not entirely defined . There has been renewed interest in further defining this reaction and transforming it into a synthetically reliable method .…”

Section: Introductionmentioning

confidence: 99%

Effect of the tether length upon Truce‐Smiles rearrangement reactions

Fuss

Grossi

et al. 2017

J of Physical Organic Chem

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This report examines the effect of substrate design upon the Truce-Smiles rearrangement, an intramolecular nucleophilic aromatic substitution reaction. The length of the molecular spacer that tethers the carbanion nucleophile to the substituted benzene ring was found to have a strong influence on the ability of the substrate to undergo the reaction successfully. Our experimental results show highest yield of desired aryl migration product for substrates designed with a 3-atom tether, which proceed through a 5-membered spirocyclic intermediate. The results are interpreted in comparison with a survey of Truce-Smiles rearrangements described in the literature and found to be consistent. Computational studies support the observed reactivity trend and suggest an explanation of a favorable combination of ring strain and electrostatic repulsion leading to optimal reactivity of the substrate designed with a 3-atom tether. Comparison of our results with trends for related ring-closing reactions illustrate the unique electrostatic features of the system studied herein.

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The Truce–Smiles rearrangement and related reactions: a review

Cited by 70 publications

References 110 publications

Radical Truce-Smiles reactions on an isoxazole template: Scope and limitations

Radical Truce-Smiles reactions on an isoxazole template: Scope and limitations

Density Functional Theory Evaluation of a Photoinduced Intramolecular Aryl Ether Rearrangement

Effect of the tether length upon Truce‐Smiles rearrangement reactions

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