scholarly journals Brønsted acid catalysis of photosensitized cycloadditions

2020 ◽  
Vol 11 (3) ◽  
pp. 856-861 ◽  
Author(s):  
Evan M. Sherbrook ◽  
Hoimin Jung ◽  
Dasol Cho ◽  
My-Hyun Baik ◽  
Tehshik P. Yoon
Keyword(s):  
Energy Transfer ◽  
Acid Catalysis ◽  
Reorganization Energy ◽  
Transfer Reactions ◽  
Bronsted Acids ◽  
Bronsted Acid ◽  
Triplet Energy ◽  
Dft Computations ◽  
Brönsted Acid ◽  
Triplet Energy Transfer

Brønsted acids can catalyze triplet energy transfer reactions, and DFT computations suggest the unexpected importance of reorganization energy for catalysis.

Brønsted acids of anionic chiral Co(iii) complexes as catalysts for the stereoselective synthesis of cis-4-aminofuranobenzopyrans

2017 ◽  
Vol 15 (43) ◽  
pp. 9077-9080 ◽  
Author(s):  
Hua-Jie Jiang ◽  
Kun Liu ◽  
Jing Wang ◽  
Na Li ◽  
Jie Yu
Keyword(s):  
Acid Catalysis ◽  
Stereoselective Synthesis ◽  
Bronsted Acids ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brönsted Acid ◽  
Povarov Reaction ◽  
Bronsted Acid Catalysis

A highly enantioselective interrupted Povarov reaction of salicylaldimines was developed, through the elegant Brønsted acid catalysis of anionic chiral Co(iii) complexes.

scholarly journals Enantioselective [2+2] Cycloadditions of Cinnamate Esters: Generalizing Lewis Acid Catalysis of Triplet Energy Transfer

2019 ◽  
Vol 141 (24) ◽  
pp. 9543-9547 ◽  
Author(s):  
Mary Elisabeth Daub ◽  
Hoimin Jung ◽  
Byung Joo Lee ◽  
Joonghee Won ◽  
Mu-Hyun Baik ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Lewis Acid ◽  
Acid Catalysis ◽  
Lewis Acid Catalysis ◽  
Triplet Energy ◽  
Triplet Energy Transfer

Thymine Dimerization Induced by Oxidative DNA Lesions and Epigenetic Intermediates via Triplet-Triplet Energy Transfer

2020 ◽  
Author(s):  
Mauricio Lineros-Rosa ◽  
Antonio Francés-Monerris ◽  
Antonio Monari ◽  
Miguel Angél Miranda ◽  
Virginie Lhiaubet-Vallet
Keyword(s):  
Energy Transfer ◽  
Excitation Energy ◽  
Transient Absorption ◽  
Theoretical Calculations ◽  
Dna Lesions ◽  
Transient Absorption Spectroscopy ◽  
Triplet Energy ◽  
Pyrimidine Dimers ◽  
Triplet Energy Transfer ◽  
Dna Nucleobases

Interaction of nucleic acids with light is a scientific question of paramount relevance not only in the understanding of life functioning and evolution, but also in the insurgence of diseases such as malignant skin cancer and in the development of biomarkers and novel light-assisted therapeutic tools. This work shows that the UVA portion of sunlight, not absorbed by canonical DNA nucleobases, can be absorbed by 5-formyluracil (ForU) and 5-formylcytosine (ForC), two ubiquitous oxidative lesions and epigenetic intermediates present in living beings in natural conditions. We measure the strong propensity of these molecules to populate triplet excited states able to transfer the excitation energy to thymine-thymine dyads, inducing the formation of the highly toxic and mutagenic cyclobutane pyrimidine dimers (CPDs). By using steady-state and transient absorption spectroscopy, NMR, HPLC, and theoretical calculations, we quantify the differences in the triplet-triplet energy transfer mediated by ForU and ForC, revealing that the former is much more efficient in delivering the excitation energy and producing the CPD photoproduct. Although significantly slower than ForU, ForC is also able to harm DNA nucleobases and therefore this process has to be taken into account as a viable photosensitization mechanism. The present findings evidence a rich photochemistry crucial to understand DNA photodamage and of potential use in the development of biomarkers and non-conventional photodynamic therapy agents.

Sulfur-Mediated Reactions through Sulfonium Salts and Ylides

Synlett ◽  
2021 ◽  
Author(s):  
Pingfan Li
Keyword(s):  
Transition Metal ◽  
Rational Design ◽  
Acid Catalysis ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Bronsted Acid ◽  
Proof Of Concept ◽  
Sulfonium Salts ◽  
Brönsted Acid ◽  
Sulfonium Ylides

AbstractThis Account discusses several new reaction methods developed in our group that utilize sulfur-mediated reactions through sulfonium salts and ylides, highlighting the interplay of rational design and serendipity. Our initial goal was to convert aliphatic C–H bonds into C–C bonds site-selectively, and without the use of transition-metal catalysts. While a proof-of-concept has been achieved, this target is far from being ideally realized. The unexpected discovery of an anti-Markovnikov rearrangement and subsequent studies on difunctionalization of alkynes were much more straightforward, and eventually led to the new possibility of asymmetric N–H insertion of sulfonium ylides through Brønsted acid catalysis.1 Introduction2 Allylic/Propargylic C–H Functionalization3 Anti-Markovnikov Rearrangement4 Difunctionalization of Alkynes5 Asymmetric N–H Insertion of Sulfonium Ylides6 Conclusion

Practical catalytic enantioselective synthesis of 2,3-dihydroquin-azolinones by chiral brønsted acid catalysis

2021 ◽  
Author(s):  
Yongbiao Guo ◽  
Zhenhua Gao ◽  
Junchen Li ◽  
Xiaojing Bi ◽  
Enxue Shi ◽  
...  
Keyword(s):  
Phosphoric Acid ◽  
Acid Catalysis ◽  
Enantioselective Synthesis ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brönsted Acid ◽  
Chiral Bronsted Acid ◽  
Bronsted Acid Catalysis

An efficient, practical and scalable protocol to prepare chiral 2,3-dihydroquinazolinones was developed under catalysis of spirocyclic SPINOL-phosphoric acid.

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