Article
Chemistry, Organic
Jian-Xiang Zhu, Fu Pi, Teng Sun, Wen-Yu Huang, Lu Gao, Zhi-Chao Chen, Wei Du, Ying-Chun Chen
Summary: This article introduces a palladium-catalyzed tandem reaction that proceeds through sequential 2,4-dienylation/Michael addition/pi-sigma-pi isomerization/allylic alkylation. Using ortho-functionalized aryl enones and 2,4-dienyl carbonates as substrates, enantioenriched architectures with fused and spirocyclic frameworks are constructed in moderate to excellent yields and stereoselectivity. Importantly, the intrinsic intramolecular Diels-Alder reaction pattern of the dienylated intermediates is effectively reversed via Pd(0)-pi-Lewis base catalysis.
Article
Chemistry, Multidisciplinary
Kyu-Hyun Sim, Thameem ul Ansari, Yong-Gyu Park, Yeolib Jeong, Sang-Ha Oh, Hye-Won Min, Da-Yoon Jeon, Hyunwoo Kim, Cheon-Gyu Cho
Summary: This study reports the intramolecular Diels-Alder reactions of 2-pyrones with a chiral branched allylic silyl ether substituent, showing remarkably high pi-facial- and endo-selectivities. The resulting diastereomerically and enantiomerically pure cycloadducts were transformed into the natural products (+)-lycopladine A and (-)-lycoposerramine R.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Guang-Chao Feng, Jun-Chi Li, Xiang Huang, Ji-Kai Liu, Bin Wu, Jin-Ming Yang
Summary: A novel cascade gold(I)-catalyzed hydroarylation of alkynylindoles and subsequent Diels-Alder cycloaddition with electron-deficient alkynes and alkenes is reported herein. The method features low catalyst loadings, high regioselectivity, broad functional group tolerances, access to important heterocycles, and 100% atom economy.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Organic
Hongling Wang, Qiangqiang Zhang, Shuai Xiao, Guanjie Wang, Xuan Huang, Xingkuan Chen, Junmin Zhang
Summary: We have developed a N-heterocyclic carbene (NHC) and base-mediated [3 + 3] annulation reaction for the synthesis of enantioselective dihydropyrano[3,2-b]indoles. Easily prepared sulfonium salts were used as precursors and reacted with unsaturated acyl azolium to achieve this transformation. The reaction conditions are mild and result in privileged indole-fused dihydropyranones with moderate to good yields and excellent enantioselectivities.
ORGANIC CHEMISTRY FRONTIERS
(2023)
Article
Chemistry, Multidisciplinary
Min Zhu, Hao Xu, Xiao Zhang, Chao Zheng, Shu-Li You
Summary: Herein, we report visible-light-induced intramolecular double dearomative cycloaddition of arenes, which provides a wide substrate scope for the synthesis of structurally diverse polycyclic indoline derivatives in high yields and with exclusive diastereoselectivity.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Huy Tran, Guillaume Revol, Alyson Poyser, Louis Barriault
Summary: In this study, a novel Lewis acid gold catalyst was used to generate synthetically challenging polycyclic scaffolds through a one-pot cascade sequence. By controlling the ligand and reaction conditions, both 6,6,5-tricyclic and 6,6,6,5-tetracyclic cores were selectively synthesized in one operation.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Razvan C. Cioc, Marc Crockatt, Jan C. van Der Waal, Pieter C. A. Bruijnincx
Summary: A hydrazine-mediated approach was used to produce renewable aromatics by Diels-Alder aromatization of biobased furfurals. The synthesis of aromatics using this method was selective, simple, and mild.
Article
Chemistry, Organic
Ruyu Xie, Zhiqiang Zhao, Yongxing Zhao, Rui Li, Jinzhong Yao, Maozhong Miao
Summary: Via Cu(I)-catalyzed cycloisomerization, readily available allenyl ketones bearing a cyclopropyl moiety can form in situ furan-fused cyclobutenes, which are highly reactive and powerful species that can undergo annulative fragmentation with terminal ynones to produce a wide variety of functional furans in moderate to high yields. This ring-distortion protocol features an unprecedented strain-controlled cycloisomerization/Diels-Alder/retro-Diels-Alder (CDRD) sequence under mild conditions.
Article
Chemistry, Applied
Sloan Ayers, Gregory L. Beutner, Wei Ding, Carolyn Higman, Charles Pathirana, Robert Wethman
Summary: Having reliable methods to monitor catalyst activation processes is crucial for ensuring the reproducibility of catalytic reactions. For asymmetric Diels-Alder reactions, chiral oxazaborolidine or oxazaborolidinium catalysts are powerful reagents that promote these reactions with high yield and selectivity. By investigating the mechanism, several modern analytical methods are compared to quantitate the formation of oxazaborolidine catalyst from amino alcohol and boroxine, leading to useful monitoring methods for this important transformation.
ORGANIC PROCESS RESEARCH & DEVELOPMENT
(2022)
Article
Chemistry, Multidisciplinary
Jan Faehrmann, Gerhard Hilt
Summary: The study presents the acyl nitroso Diels-Alder reaction of 1,3-dienes with electrochemically oxidised hydroxamic acids. By utilizing alternating current electrolysis and optimizing the reaction conditions through Design of Experiments, high purity products were obtained with yields up to 96%, without the need for further purification.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Organic
Casper Larsen Barlose, Jonas Faghtmann, Rene Slot Bitsch, Joseph Daniel Gbubele, Karl Anker Jorgensen
Summary: The combination of asymmetric organocatalysis with the (pseudo)-halogen effect allows for the efficient formation of chiral norcarane scaffolds. These scaffolds can easily undergo rearrangements or lactonization to form intricate chiral ring structures.
Article
Chemistry, Multidisciplinary
Nicole Houszka, Hannes Mikula, Dennis Svatunek
Summary: 1,2,4,5-Tetrazines are widely used in bioorthogonal chemistry for their high reactivity in Diels-Alder reactions. The substituents in the 3- and 6-positions of the tetrazine scaffold significantly affect the rate of cycloadditions, but this is not explained by frontier molecular orbital interactions. Instead, the high reactivity of mono-substituted tetrazines is due to decreased Pauli repulsion, leading to a more asynchronous approach and reduced distortion energy. Additionally, ethylene is not a good model compound for other alkenes in Diels-Alder reactions.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Zhimei Mao, Aimin Huang, Lin Ma, Min Zhang
Summary: A facile visible light-promoted approach has been developed for the synthesis of anthracenone-furans from readily available 2,3-dibromonaphthoquinones and phenylbenzofurans via a formal Diels Alder reaction. This reaction involves wavelength-selective agitation of 4CzIPN, energy transfer to quinones, recombination of 1,6-biradicals, and elimination to give anthracenone-furans in good to excellent yields in one pot.
Article
Polymer Science
Jie Yan, Marta Krasowska, Wei Ge, Kirsten Platts, Paula Facal Marina, Anton Blencowe
Summary: Injectable hydrogels with tuneable properties were developed for sustained drug delivery. These hydrogels can be easily processed at ambient temperature, and rapidly gel at physiological temperature to limit burst release of their payload.
EUROPEAN POLYMER JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Casper L. Barlose, Niklas L. ostergaard, Rene S. Bitsch, Marc V. Iversen, Karl Anker Jorgensen
Summary: An enantioselective methodology for constructing trans-Diels-Alder scaffolds with up to five contiguous stereocenters is presented, utilizing a halogen effect and a novel discovered pseudo-halogen effect. The reaction involves an endo-selective, secondary-amine catalyzed Diels-Alder reaction followed by a subsequent S(N)2-like reaction at a tertiary center to obtain the trans-Diels-Alder scaffold. The mechanism was supported by experimental results and computational studies.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Christopher S. Gravatt, Luis Melecio-Zambrano, Tehshik P. Yoon
Summary: The sole method available for the photocycloaddition of unconjugated aliphatic alkenes is the Cu-catalyzed Salomon-Kochi reaction. A new catalyst system with superior reactivity and photostability has been designed, offering significantly expanded substrate scope and highlighted through the preparation of the natural products sulcatine G and perforatol.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Nicholas L. Reed, Grace A. Lutovsky, Tehshik P. Yoon
Summary: This study demonstrates that Cu(II)-mediated radical-polar crossover enables efficient photocatalytic oxidative heterofunctionalization reactions between bulky alkenes and various nucleophilic partners. It shows that Cu(II) salts are ideal terminal oxidants for photoredox applications, and the combination of photocatalytic substrate activation and Cu(II)-mediated radical oxidation can address challenges in catalytic oxidation chemistry.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Chemistry, Organic
Spencer O. Scholz, Jesse B. Kidd, Luca Capaldo, Niecia E. Flikweert, Rowan M. Littlefield, Tehshik P. Yoon
Summary: This study presents a photosensitized [2 + 2] cycloaddition reaction for the straightforward access to complex cyclobutane scaffolds. Mechanistic studies suggest an activation mode involving energy transfer to the styrenyl alkene rather than the vinyl boronate ester.
Article
Chemistry, Organic
Xiao Dong, Qi Yukki Li, Tehshik P. Yoon
Summary: The research shows that in designing photochemical reactions, not only the excited-state oxidation potential is important, but also the oxidation and reduction potentials of the photocatalyst are crucial for the reaction outcome. This highlights the importance of holistic considerations in designing photochemical reactions.
Review
Chemistry, Multidisciplinary
Matthew J. Genzink, Jesse B. Kidd, Wesley B. Swords, Tehshik P. Yoon
Summary: Asymmetric photocatalysis is a major research topic in contemporary synthetic organic chemistry. However, the discovery of general strategies for highly enantioselective photochemical reactions has been a recent development, leading to a somewhat limited variety of stereocontrolled photoreactions. This review summarizes the chiral catalyst structures that have been studied for solution-phase asymmetric photochemistry, providing insight into the logic required for highly effective stereocontrolled photocatalysis.
Article
Chemistry, Multidisciplinary
Steven J. Chapman, Wesley B. Swords, Christine M. Le, Ilia A. Guzei, F. Dean Toste, Tehshik P. Yoon
Summary: Stereoinduction in complex organic reactions often involves the interaction of multiple stereocontrol elements, with the potential for significant cooperative effects. This study presents a strategy for enantioselective photocycloaddition reactions using a tandem chiral photocatalyst/Bronsted acid approach. The matched and mismatched chiral catalyst pairs show different reaction rates and enantioselectivities, suggesting the importance of similar matched/mismatched effects in other types of enantioselective dual-catalytic photochemical reactions.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Multidisciplinary
Qi Yukki Li, Samuel N. Gockel, Grace A. Lutovsky, Kimberly S. DeGlopper, Neil J. Baldwin, Mark W. Bundesmann, Joseph W. Tucker, Scott W. Bagley, Tehshik P. Yoon
Summary: Reactions that allow for the formation of carbon-nitrogen, carbon-oxygen, and carbon-carbon bonds are crucial in synthetic chemistry. This study presents a copper-mediated, net-oxidative decarboxylative coupling reaction under visible-light irradiation, which enables the conversion of substrates without requiring harsh reaction conditions.
Article
Chemistry, Organic
Wesley B. Swords, Steven J. Chapman, Heike Hofstetter, Anna L. Dunn, Tehshik P. Yoon
Summary: LED-NMR is a rapid and convenient method for directly monitoring the in-situ photocatalytic reaction. The study using LED-NMR reveals a change in mechanism between reactions conducted at different temperatures. These results highlight the sensitivity of photocatalytic reaction mechanisms to precise reaction conditions.
JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Andrew Whyte, Tehshik P. P. Yoon
Summary: Carboxylic acids are attractive building blocks in synthetic chemistry due to their stability, abundance, and structural diversity. The ketonization reaction, which combines two carboxylic acids to produce a ketone, has been underutilized due to harsh reaction conditions and lack of selectivity. We report a new strategy that utilizes metallaphotoredox to selectively generate unsymmetrical ketones by cross-ketonization of structurally dissimilar carboxylic acids.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Zebediah C. Girvin, Laura F. Cotter, Hyung Yoon, Steven J. Chapman, James M. Mayer, Tehshik P. Yoon, Scott J. Miller
Summary: High selectivity in photochemical reactions can be achieved by controlling the transition state.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Organic
Grace A. Lutovsky, Ellie F. Plachinski, Nicholas L. Reed, Tehshik P. Yoon
Summary: A method for allylic amination using photoredox activation and Cu(II)-mediated radical-polar crossover is described. This strategy allows the synthesis of a range of structurally varied allylic amines. The regioselectivity of this process complements that of conventional methods for allylic amination.
Article
Chemistry, Organic
Riley M. Kelch, Andrew Whyte, Eunji Lee, Tehshik P. Yoon
Summary: Here, it is demonstrated that the addition of Lewis acid co-catalysts can greatly expand the range of alkenes that can participate in the photosensitized visible-light De Mayo reaction. Mechanistic studies indicate that the primary advantage of Lewis acid is not on substrate sensitization, but rather on bond-forming steps after energy transfer, illustrating the versatile effects Lewis acids can have on sensitized photoreactions.
Article
Chemistry, Multidisciplinary
Grace A. Lutovsky, Samuel N. Gockel, Mark W. Bundesmann, Scott W. Bagley, Tehshik P. Yoon
Summary: In this study, a direct decarboxylative cross-coupling of native carboxylic acids with nucleophilic coupling partners mediated by inexpensive and non-toxic Fe(III) salts was reported. This method involves an initial photochemical decarboxylation followed by radical-polar crossover, enabling the construction of diverse carbon-carbon, carbon-oxygen, and carbon-nitrogen bonds with remarkable generality.
Article
Chemistry, Multidisciplinary
Matthew J. J. Genzink, Matthew D. D. Rossler, Herman Recendiz, Tehshik P. P. Yoon
Summary: Chiral acid catalysts are shown to promote highly selective visible-light photocycloadditions, leading to the synthesis of truxinate natural products. This general approach allows for the efficient synthesis of dimeric and pseudodimeric cyclobutane natural products with excellent enantioselectivity.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Review
Chemistry, Organic
Grace A. Lutovsky, Tehshik P. Yoon
Summary: Photochemistry provides a crucial platform for the discovery of useful synthetic transformations, but developing new oxidative photoreactions has proven to be challenging. This review highlights recent reaction methods that utilize Cu(II) oxidation in combination with photochemical activation of substrates or use Cu(II) salts as both the active chromophore and terminal oxidant.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2023)
Article
Chemistry, Organic
Geeta Devi Yadav, Pooja Chaudhary, Balaram Pani, Surendra Singh
Summary: Chiral transition metal complexes with privileged ligands are efficient catalysts for various asymmetric organic transformations. Transition metal complexes of C1-symmetric pyrrolidine-based ligands have been widely used in asymmetric organic reactions. However, a comprehensive review article on the transition metal complexes of chiral C1-symmetric pyrrolidine-based ligands derived from (L)-proline has not been published.
TETRAHEDRON LETTERS
(2024)