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Exohedral Diels‐Alder Reactivity of Endohedral Metallofullerene C₃₆

Athul Santha Bhaskaran, Dani Romero del Blanco, Adrià Romero‐Rivera, Sílvia Osuna, more

Chemistry – A European Journal > 30 > 58 > n/a - n/a

Understanding the exohedral reactivity of metallofullerenes is crucial for its application in various fields. By systematically controlling the trapped species inside the fullerene its reactivity can be tamed. In this work we report the preferential position of 3d metal atoms inside the C₃₆ cage and their effect on exohedral reactivity in comparison with the neutral and the dianionic cage. The Diels‐Alder...

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Unexpectedly Regioselective Diels‐Alder Reactions of New Unsymmetrical Benzoquinones: A Convenient Synthetic Entry to Uniquely Substituted Decalins

Lukáš Maier, Dana Němečková, Naresh Akavaram, Erik Kalla, more

Chemistry – A European Journal > 30 > 55 > n/a - n/a

We report flexible synthesis of new unsymmetrically 2,6‐disubstituted benzoquinones (33 examples) and a systematic study of their reactivity in the Diels‐Alder reaction. The Diels‐Alder reactions of selected unsymmetrical benzoquinones with seemingly similar substituents were found to proceed with high regioselectivity and the formation of selected experimentally observed main products was rationalized...

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HFIP‐Promoted Short Total Synthesis of Gochnatiolide D and Ainsliadimer A from Dehydrozaluzanin C

Antonis Kelesidis, Kyriaki Gennaiou, Alexandros L. Zografos

European Journal of Organic Chemistry > 27 > 33 > n/a - n/a

The total syntheses of gochnatiolide D and ainsliadimer A were achieved through a streamlined one‐pot sequence starting from their biogenetic precursor dehydrozaluzanin C. These biomimetic, protecting group‐free syntheses involve the elegant orchestration of the highly diastereoselective hetero‐Diels‐Alder reaction of dehydrozaluzanin C, its subsequent hydrolysis to gochnatiolide D and finally an...

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Bowl‐Shaped Kekulene Analogues: Cycloarenes with two Five‐Membered Rings

Hideyuki Murakami, Hiroki Iwabuchi, Miki Asari, Hiroko Yamada, more

Chemistry – A European Journal > 30 > 45 > n/a - n/a

Kekulene, a cycloarene composed of 12 fused benzene rings in a circular arrangement, exhibits a highly planar and robust structure. Kekulene has been the subject of investigation into its aromaticity and electronic structure, particularly in relation to the cyclic benzenoid. We have successfully synthesized novel bowl‐shaped kekulene analogues with five‐membered rings incorporated into the kekulene...

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Direct Diels‐Alder Reaction of Biomass‐Derived Furfurol with Maleimides in a Bio‐Based Green Solvent

Elpida Skolia, Christoforos G. Kokotos

European Journal of Organic Chemistry > 27 > 15 > n/a - n/a

Environmental concern has motivated an inclination to exploit waste and upgrade it into high‐added‐value chemicals. Biomass is an excellent carbon source that provides a variety of raw materials as building blocks, such as furans. Herein, we report the upcycling of furfurol, a known biomass by‐product, through a Diels‐Alder cycloaddition with maleimides that is performed in a green bio‐derived solvent,...

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Synergistic topological and supramolecular control of Diels‐Alder reactivity based on a tunable self‐complexing host‐guest molecular switch

Cédric Ribeiro, Michele Cariello, Aurélie Malfait, Marc Bria, more

Chemistry – A European Journal > 30 > 11 > n/a - n/a

Compartmentalization and binding‐triggered conformational change regulate many metabolic processes in living matter. Here, we have synergistically combined these two biorelevant processes to tune the Diels‐Alder (DA) reactivity of a synthetic self‐complexing host‐guest molecular switch CBPQT⁴⁺‐Fu, consisting of an electron‐rich furan unit covalently attached to the electron‐deficient cyclobis(paraquat‐p‐phenylene)...

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Cover Feature: Mechanistic Studies on the Bidentate Lewis Acid Catalyzed Domino Inverse Electron‐Demand Diels‐Alder/Thiol Transfer Reaction (Eur. J. Org. Chem. 8/2023)

Sebastian Beeck, Hermann A. Wegner

European Journal of Organic Chemistry > 26 > 8 > n/a - n/a

The Cover Feature shows a shot pendulum symbolizing the group transfer reaction studied in our paper. The balls of the pendulum represent the functional groups participating in the GTR, which are the thiol group and the ortho‐quinodimethane intermediate. The latter is represented on two balls as it consists of two separate groups: the naphthalene framework and the chiral amine. The “thiol‐ball” swings...

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Mechanistic Studies on the Bidentate Lewis Acid Catalyzed Domino Inverse Electron‐Demand Diels‐Alder/Thiol Transfer Reaction

Sebastian Beeck, Hermann A. Wegner

European Journal of Organic Chemistry > 26 > 8 > n/a - n/a

Recently, we presented a novel enantioselective multicomponent reaction of phthalazines, aldehydes and thiols accessing thioether‐substituted 1,2‐dihydronaphthalenes. Herein, a comprehensive investigation on the mechanism of this domino inverse electron‐demand (IEDDA)/thiol transfer reaction is disclosed. In particular, the origin of the stereochemical outcome has been rationalized, as well as structural...

article

Two‐Factor Fluorogenicity of Tetrazine‐Modified Cyanine‐Styryl Dyes for Bioorthogonal Labelling of DNA

Philipp Geng, Eileen List, Franziska Rönicke, Hans‐Achim Wagenknecht

Chemistry – A European Journal > 29 > 8 > n/a - n/a

Two green fluorescent tetrazine‐modified cyanine‐styryl dyes were synthesized for bioorthogonal labelling of DNA by means of the Diels‐Alder reaction with inverse electron demand. With DNA as target biopolymer the fluorescence of these dyes is released by two factors: (i) sterically by their interaction with DNA, and (ii) structurally via the conjugated tetrazine as quencher moiety. As a result, the...

article

Front Cover: Light‐Driven Catalyst‐Free Access to Phthalazines: Entry to Antiviral Model Drugs by Merging Domino Reactions (Eur. J. Org. Chem. 5/2023)

Anton Guryev, Florian Schuster, Lars Herrmann, Friedrich Hahn, more

European Journal of Organic Chemistry > 26 > 5 > n/a - n/a

The Front Cover shows a light‐induced enolization of o‐methyl benzophenones/Diels–Alder reaction, combined with deprotection/aromatization steps in one pot toward new antiviral phthalazines. The Temple of Jupiter in the background is a colossal Roman temple in sunny Baalbek (Lebanon), that was dedicated to Jupiter Heliopolitanus, known as a SUN God. The columns of the temple on this cover picture...

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Light‐Driven Catalyst‐Free Access to Phthalazines: Entry to Antiviral Model Drugs by Merging Domino Reactions**

Anton Guryev, Florian Schuster, Lars Herrmann, Friedrich Hahn, more

European Journal of Organic Chemistry > 26 > 5 > n/a - n/a

We report the development of a metal‐free four‐step one‐pot synthetic strategy to access high‐value functionalized phthalazines using o‐methyl benzophenones as starting compounds. Combining a light‐mediated enolization of o‐methyl benzophenones/Diels‐Alder reaction domino process with a subsequent deprotection/aromatization domino reaction in one‐pot leads to sustainable and efficient organic synthesis...

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Theoretical Study on Chiral Boron Complex‐Promoted Asymmetric Diels‐Alder Cycloadditions

Miglena K. Georgieva, A. Gil Santos

European Journal of Organic Chemistry > 2022 > 45 > n/a - n/a

The Diels‐Alder reaction is a very interesting process that has been deeply studied in its achiral version. More recently, in its chiral version, it has also been the focus of many experimental and theoretical reports. Here, we study the Diels‐Alder reaction of 2′‐hydroxychalcones, as dienophiles, with two dienes, catalyzed by chiral organo‐boron Lewis acid complexes. We theoretically evaluate the...

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BF₃ ⋅ Et₂O Promoted Inverse‐Electron‐Demand Oxa‐Diels‐Alder Reaction of Alkylidene Isoxazol‐5‐ones with Unactivated Alkenes

Yu Zheng, Shencheng Qian, Pengcheng Xu, Tianting Ma, more

Advanced Synthesis & Catalysis > 364 > 22 > 3800 - 3804

The synthesis of fused dihydropyran isoxazole derivatives has been developed by employing an intermolecular inverse‐electron‐demand Diels‐Alder reaction of readily available alkylidene isoxazol‐5‐ones with unactivated alkenes. The reaction was promoted by inexpensive and commercially available BF₃ ⋅ Et₂O without the use of metal Lewis acids. This cycloaddition transformation could proceed under mild...

article

Benzo[c][1,2]thiazine‐Based Analogs in the Inverse Electron Demand [4+2] Hetero Diels‐Alder Reaction with Glycals: Access to Tetracyclic Fused Galactose and Fucose Derivatives

Giacomo Biagiotti, Laura Legnani, Giusi Aresta, Maria A. Chiacchio, more

European Journal of Organic Chemistry > 2022 > 43 > n/a - n/a

The synthesis and reactivity in an [4+2] inverse electron demand hetero Diels‐Alder reaction (ihDA) of an original class of electron‐poor heterodienes, the N‐substituted‐1H‐benzo[c][1,2]thiazin‐4‐one‐2,2‐dioxides, are described. These are highly reactive electrophiles that allow easy access to unprecedented benzo‐thiazine glyco‐fused derivatives in a remarkably selective way, even when using acetylated...

article

Asymmetric Cycloaddition/Annulation Reactions by Chiral Phosphoric Acid Catalysis: Recent Advances

Alemayehu Gashaw Woldegiorgis, Muhammad Suleman, Xufeng Lin

European Journal of Organic Chemistry > 2022 > 34 > n/a - n/a

Asymmetric cycloaddition/annulation reactions have contributed greatly to the synthesis of a variety of novel cyclic compounds used in organic synthesis, natural product synthesis, material science, and chemical biology. Thus, chiral phosphoric acid‐catalyzed asymmetric cycloaddition reactions have received the attention of the synthetic community to design new vital asymmetric reactions and synthesize...

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Studies towards the Total Synthesis of Amycolamicin: A Chiral Auxiliary‐Based Diels‐Alder Approach towards the Decalin Core

Thomas M. Frossard, Nils Trapp, Karl‐Heinz Altmann

European Journal of Organic Chemistry > 2022 > 30 > n/a - n/a

The stereoselective synthesis of (1S,2S,5R)‐5‐((4‐methoxybenzyl)oxy)‐2‐methyl‐8‐methylene‐1,2,4a,5,6,7,8,8a‐octahy‐dronaphthalene‐1‐carboxylic acid (2) is described, which comprises the bicyclic core structure of the natural product amycolamicin (1). The bicyclic ring‐system was established via an intramolecular Diels‐Alder reaction of a triene carrying a SuperQuat chiral auxiliary. The latter could...

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Front Cover: How Ionization Catalyzes Diels‐Alder Reactions (Chem. Eur. J. 40/2022)

Pascal Vermeeren, Trevor A. Hamlin, F. Matthias Bickelhaupt

Chemistry – A European Journal > 28 > 40 > n/a - n/a

Ionization of the dienophile is an effective method to enhance the Diels–Alder reaction between buta‐1,3‐diene and acrylaldehyde. The origin of this ionization catalysis is both a reduction in steric Pauli repulsion and simultaneous enhancement of the orbital interactions between the reactants. Our work demonstrates the similarities and differences between radical–cation and Lewis acid‐catalyzed Diels–Alder...

article

How Ionization Catalyzes Diels‐Alder Reactions

Pascal Vermeeren, Trevor A. Hamlin, F. Matthias Bickelhaupt

Chemistry – A European Journal > 28 > 40 > n/a - n/a

The catalytic effect of ionization on the Diels‐Alder reaction between 1,3‐butadiene and acrylaldehyde has been studied using relativistic density functional theory (DFT). Removal of an electron from the dienophile, acrylaldehyde, significantly accelerates the Diels‐Alder reaction and shifts the reaction mechanism from concerted asynchronous for the neutral Diels‐Alder reaction to stepwise for the...

article

Chasing Polycyclic Natural Products: 5/6/5‐ or 5/6/6‐Carbotricyclic Scaffold Construction via Stereodivergent Diels‐Alder Reaction of Chiral Hydrindanes and Their Boron Complexes

Yannick Stöckl, Thomas Fellmeth, Florian Bauer, Bianca Wank, more

European Journal of Organic Chemistry > 2022 > 26 > n/a - n/a

Chiral trans‐hydrindanes (bicyclo[4.3.0]nonanes) are important building blocks of polycyclic natural products. In order to access 5/6/5‐ and 5/6/6‐carbotricyclic scaffolds scope and limitation of [4+2] cycloadditions of tetrahydroindanones with various dienes were studied. Cyclopentadiene gave a tetracylic endo‐(R,R)‐diastereomer under acid‐catalysis, whereas thermal conditions provided the endo‐(...

article

Knoevenagel‐Cyclization Cascade Reactions of Substituted 5,6‐Dihydro‐2H‐Pyran Derivatives

Sándor Balázs Király, Attila Bényei, Erika Lisztes, Tamás Bíró, more

European Journal of Organic Chemistry > 2021 > 45 > 6161 - 6170

The diastereoselective domino‐Knoevenagel‐IMHDA reactions of 5,6‐dihydro‐2H‐pyran derivatives containing an o‐formylaryl amine or ether moiety were performed with active methylene reagents. In the spiro heterocyclic products representing a novel skeleton, a tetrahydroquinoline or chroman unit is fused with two pyran rings and the bridgehead carbon atoms are chirality centers formed diastereoselectively...

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Search results

Exohedral Diels‐Alder Reactivity of Endohedral Metallofullerene C₃₆

Unexpectedly Regioselective Diels‐Alder Reactions of New Unsymmetrical Benzoquinones: A Convenient Synthetic Entry to Uniquely Substituted Decalins

HFIP‐Promoted Short Total Synthesis of Gochnatiolide D and Ainsliadimer A from Dehydrozaluzanin C

Bowl‐Shaped Kekulene Analogues: Cycloarenes with two Five‐Membered Rings

Direct Diels‐Alder Reaction of Biomass‐Derived Furfurol with Maleimides in a Bio‐Based Green Solvent

Synergistic topological and supramolecular control of Diels‐Alder reactivity based on a tunable self‐complexing host‐guest molecular switch

Cover Feature: Mechanistic Studies on the Bidentate Lewis Acid Catalyzed Domino Inverse Electron‐Demand Diels‐Alder/Thiol Transfer Reaction (Eur. J. Org. Chem. 8/2023)

Mechanistic Studies on the Bidentate Lewis Acid Catalyzed Domino Inverse Electron‐Demand Diels‐Alder/Thiol Transfer Reaction

Two‐Factor Fluorogenicity of Tetrazine‐Modified Cyanine‐Styryl Dyes for Bioorthogonal Labelling of DNA

Front Cover: Light‐Driven Catalyst‐Free Access to Phthalazines: Entry to Antiviral Model Drugs by Merging Domino Reactions (Eur. J. Org. Chem. 5/2023)

Light‐Driven Catalyst‐Free Access to Phthalazines: Entry to Antiviral Model Drugs by Merging Domino Reactions**

Theoretical Study on Chiral Boron Complex‐Promoted Asymmetric Diels‐Alder Cycloadditions

BF₃ ⋅ Et₂O Promoted Inverse‐Electron‐Demand Oxa‐Diels‐Alder Reaction of Alkylidene Isoxazol‐5‐ones with Unactivated Alkenes

Benzo[c][1,2]thiazine‐Based Analogs in the Inverse Electron Demand [4+2] Hetero Diels‐Alder Reaction with Glycals: Access to Tetracyclic Fused Galactose and Fucose Derivatives

Asymmetric Cycloaddition/Annulation Reactions by Chiral Phosphoric Acid Catalysis: Recent Advances

Studies towards the Total Synthesis of Amycolamicin: A Chiral Auxiliary‐Based Diels‐Alder Approach towards the Decalin Core

Front Cover: How Ionization Catalyzes Diels‐Alder Reactions (Chem. Eur. J. 40/2022)

How Ionization Catalyzes Diels‐Alder Reactions

Chasing Polycyclic Natural Products: 5/6/5‐ or 5/6/6‐Carbotricyclic Scaffold Construction via Stereodivergent Diels‐Alder Reaction of Chiral Hydrindanes and Their Boron Complexes

Knoevenagel‐Cyclization Cascade Reactions of Substituted 5,6‐Dihydro‐2H‐Pyran Derivatives

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