Synthesis of Cycloheptatrienes, Oxepines, Thiepines, and Silepines: A Comparison between Brønsted Acid and Au‐Catalysis

Sprenger, Kristin; Golz, Christopher; Alcarazo, Manuel

doi:10.1002/ejoc.202001072

Cited by 21 publications

(18 citation statements)

References 52 publications

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“…Finally, the cyclizations of 1-benzyl-2-ethynylbenzenes were investigated by the group of Alcarazo. 68 Brønsted acid-catalysis by 50 mol% of HNTf2 gave the carbocyclization products resulting from the most stable vinyl cations via 6-exo-dig or 7-endo-dig processes depending on the structure of the starting material (Scheme 53). With terminal or alkyl-substituted alkynes, such as 215, the 6-exo cyclization produced the carbocycle 217, which further isomerized under acidic conditions to give the anthracene 216 in 72% yield.…”

Section: Reactions Using Sub-stoichiometric Amounts Of Bamentioning

confidence: 99%

Brønsted Acid Catalyzed Carbocyclizations Involving Electrophilic Activation of Alkynes

et al. 2022

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This review focuses on the carbocyclization reactions of alkyne-containing substrates catalyzed by Brønsted acids. The electrophilic activation occurs either by direct protonation of the alkyne or by formation of an intermediate cation that further reacts with the alkyne to give the vinyl cation key intermediate. A specific highlight will be put on the selectivity of the various methodologies described herein and on the mechanistic rationale.

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Section: Reactions Using Sub-stoichiometric Amounts Of Bamentioning

confidence: 99%

Brønsted Acid Catalyzed Carbocyclizations Involving Electrophilic Activation of Alkynes

et al. 2022

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“…The Au-catalyst activates the carbon of alkyne 124, which attacks the β-position of arene to afford the desired products 125 in good to excellent yields (Scheme 51). [50] Scheme 51 Synthesis of Dibenzo[b,f]oxepines via Au-catalyzed C-H Annulation…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Recent Advances on the Development of Synthetic Strategies to Access Dibenzoxepine Derivatives

2022

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Dibenzoxepines have gained privileged status in medicinal chemistry and drug discovery due to their appearance in various natural products and life-saving drug molecules. Dibenzoxepine based molecules such as artocarpols, asenapine and pacharin possess a wide range of biological activities including anti-inflammatory, antidepressant, antihypertensive, antiestrogenic and insecticidal activities. Therefore, designing and developing new methodologies to access dibenzoxepine core becomes a paramount research topic for organic/medicinal chemists. Herein, we reviewed various synthetic methods to access dibenzoxepine derivatives. The total syntheses of dibenzoxepine-based natural products and biologically/medicinally important molecules have also been reviewed.

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“…29 The easy synthesis of Au complexes 41a-e, their easy handling, robustness, and exceptional catalytic performance have made these pre-catalysts the standard ones used in our laboratory for explorative assays focused on the discovery of new reactivities. 30 Ongoing research targets the application of N-arylpyridiniophosphines in processes catalyzed by metals other than Au.…”

Section: Account Synlettmentioning

confidence: 99%

α-Cationic Phosphines: from Curiosities to Powerful Ancillary Ligands

Rugen¹,

Alcarazo²

2021

Synlett

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The distinguishing feature of α-cationic phosphines is the presence of at least one substituent, normally (hetero)cyclic and positively charged, which is directly attached to the phosphorus atom. As result from this unique substitution pattern, the thus designed ligands depict significantly diminished donor properties if compared with their neutral counterparts. Thus, if in a hypothetical catalytic cycle, the step that determines the rate is facilitated by an increase of the electrophilicity at the metal center; then, the use of α-cationic ancillary phosphines can be highly beneficial. This fact, combined with their easy syntheses and stability, which allows an easy handling, make α-cationic phosphines a useful tool for the synthetic practitioner. Our research on the topic demonstrates that generally a remarkable ligand acceleration effect is observed when α-cationic phosphines are employed in Au(I)- and Pt(II)-promoted cycloisomerizations; moreover, in some cases even otherwise not operative transformations can be promoted. This Account describes how we entered into the topic, our efforts, and those of others to understand the coordination behavior of α-cationic phosphines and further develop their range of applications in catalysis; but it also identifies the drawbacks associated with their use, which limit their range of application.1 Introduction2 Polycationic Phosphines: Stronger Acceptors than Phosphites3 Inconveniences Derived from the Use of (Poly)cationic phosphines4 A Second Generation of Cationic Ligands: α-Pyridiniophosphines5 Chiral α-Cationic Phosphines6 α-Radical Phosphines and (Poly)cationic Phosphine Oxides7 Conclusions and Outlook

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Synthesis of Cycloheptatrienes, Oxepines, Thiepines, and Silepines: A Comparison between Brønsted Acid and Au‐Catalysis

Cited by 21 publications

References 52 publications

Brønsted Acid Catalyzed Carbocyclizations Involving Electrophilic Activation of Alkynes

Brønsted Acid Catalyzed Carbocyclizations Involving Electrophilic Activation of Alkynes

Recent Advances on the Development of Synthetic Strategies to Access Dibenzoxepine Derivatives

α-Cationic Phosphines: from Curiosities to Powerful Ancillary Ligands

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