Article
Chemistry, Organic
Shuangwei Liu, Xiaojiao Su, Dan Jiang, Hongbing Xiong, Dingyin Miao, Lin Fu, Hanyue Qiu, Ling He, Min Zhang
Summary: A Fe(NO3)(3)-mediated ring-opening arylation of cyclopropanol with pyrrole has been developed, enabling direct arylation without prefunctionalization and providing a rapid access to chiral 5,6,7,8-tetrahydroindolizines. The utility of this method has been demonstrated by the asymmetric synthesis of alkaloids (-)-indolizidine 167B, (+)-indolizidine 209D, (+)-monomorine I, and a natural product analogue.
Article
Chemistry, Multidisciplinary
Bao-Gui Cai, Claire Empel, Wei-Zhong Yao, Rene M. Koenigs, Jun Xuan
Summary: The azoxy functional group is an important structural motif, and its synthesis, especially unsymmetric azoxy compounds, remains underdeveloped. In this study, we designed a method using readily accessible nitroso compounds and iminoiodinanes to synthesize sulfonyl-protected azoxy compounds. Visible light irradiation was used to generate a triplet nitrene from iminoiodinanes, which then reacted with nitroso arenes. The resulting sulfonyl-protected azoxy compounds showed good substrate scope and functional group tolerance. We also demonstrated the use of these compounds as radical precursors in two synthesis applications without the need for photoredox catalysts and additives.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Organic
Sensheng Liu, Martin Klussmann
Summary: Transition metals are the main catalysts for redox reactions involving peroxides and organic substrates. However, triarylamines can also act as organic redox catalysts, facilitating oxidative difunctionalization reactions of alkenes and oxidative Ritter reactions. Mechanistic studies have shown that triarylamines act as catalysts, mediating the reactions through electron transfer processes.
ORGANIC CHEMISTRY FRONTIERS
(2021)
Article
Chemistry, Multidisciplinary
Anirudra Paul, Jae Hyun Kim, Scott D. Daniel, Daniel Seidel
Summary: Despite efforts by practitioners, direct alpha-C-H bond functionalization of unprotected alicyclic amines is rare. A new method utilizing N-lithiated alicyclic amines has been developed, providing a convenient approach to achieve functionalization reactions under mild conditions. This method offers a new pathway for the synthesis of beta-amino ketones with regioselective alpha'-alkylation, and potential for one-pot synthesis of polycyclic dihydroquinolones.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Organic
Alexandria N. Leveille, Radell Echemendia, Anita E. Mattson, Antonio C. B. Burtoloso
Summary: The study reported the first example of organocatalytic enantioselective C-H insertion reactions of indoles and sulfoxonium ylides, achieving levels of enantiocontrol in the range of 20-93% ee and moderate yields (up to 50%) under phosphoric acid catalysis. It was found that no nitrogen protection on the indole is necessary for these reactions.
Article
Chemistry, Organic
Zhiqiang Deng, Zhenxiang Zhao, Gang He, Gong Chen
Summary: A new method has been developed for the photoredox-mediated delta-C(sp(3))-H fluorination of sulfonyl-protected primary alkylamines with Selectfluor. This reaction shows excellent monofluorination selectivity for amine substrates without substituents, and slightly modified reaction conditions allow for the synthesis of delta,delta-difluorination products in good yield for alpha-substituted substrates. Mechanistic studies indicate that SET oxidation of the sulfonamide group generates the key sulfonamide N radical intermediate, triggering a 1,5-HAT process to form the delta alkyl radical.
Review
Chemistry, Organic
Weijie Chen, Daniel Seidel
Summary: This review provides a comprehensive overview of condensation-based methods for C-H bond functionalization of amines using azomethine ylides as key intermediates, which allow rapid transformation of simple starting materials into complex amines.
SYNTHESIS-STUTTGART
(2021)
Article
Chemistry, Inorganic & Nuclear
Gayathri B. Gange, Amanda L. Humphries, Mark D. Smith, Dmitry V. Peryshkov
Summary: In this study, we report the reactivity of carboranyl diphosphine with terminal alkynes, resulting in the formation of boron-containing phosphacycles. The reaction combines the activation of electron-deficient alkynes by phosphine groups and the redox behavior of carborane clusters, leading to the formation of a fused product of alkenylphosphonium cycle and reduced carborane cluster.
INORGANIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Jesus Rodrigalvarez, Luke A. Reeve, Javier Miro, Matthew J. Gaunt
Summary: This article reports a simple and efficient method for introducing aryl groups into aminomethyl-cyclopropanes and -cyclobutanes through enantioselective C-H arylation, which simplifies the construction of functionalized strained aminomethyl-cycloalkanes.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Multidisciplinary
Jacob W. Greenwood, Benjamin T. Boyle, Andrew McNally
Summary: Radical couplings of cyanopyridine radical anions offer a valuable technology for functionalizing pyridines in pharmaceuticals, agrochemicals, and materials. This study demonstrates that pyridylphosphonium salts can be useful alternatives to cyanopyridines in radical-radical coupling reactions, expanding the scope of complex pyridines. Additionally, late-stage functionalization of pharmaceuticals is highlighted as an advantage of pyridylphosphonium salts over cyanopyridines.
Article
Chemistry, Multidisciplinary
Jun-Jie Tian, Wei Sun, Rui-Rui Li, Gui-Xiu Tian, Xiao-Chen Wang
Summary: A borane/gold(I) co-catalytic system was designed and applied in C-H functionalization reactions and cycloaddition reactions between tertiary amines and alpha-alkynylenones, efficiently introducing a furan ring into the amine molecule.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Organic
Pratiksha Bhorali, Jyotshna Phukon, Sanjib Gogoi
Summary: An unprecedented (5 + 2)-cycloaddition reaction between ortho-hydroxyethyl phenol and internal alkyne was developed using rhodium(iii) catalysis. This reaction provided benzoxepine derivatives with high biological significance. A wide range of ortho-hydroxyethyl phenols and internal alkynes were effectively used to obtain high yields of benzoxepines.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2023)
Article
Multidisciplinary Sciences
Guowei Kang, Daniel A. Strassfeld, Tao Sheng, Chia-Yu Chen, Jin-Quan Yu
Summary: Cyclic organic molecules are common in natural products and pharmaceuticals. This study presents two classes of ligands that enable site-selective C-H arylation of small- to medium-sized cycloalkane carboxylic acids, overcoming the challenge of strain encountered in transannular C-H palladation. This advance is a major step towards achieving molecular editing of saturated carbocycles, with demonstrated utility in the synthesis of biologically active small molecules.
Article
Chemistry, Organic
Feifei He, Rene M. Koenigs
Summary: In this study, the tris(pentafluorophenyl)borane-catalyzed reaction of carbazole heterocycles with aryldiazoacetates was reported. It was demonstrated that selective N-H or C-H functionalization could be achieved with good yields under different substrate conditions. The method showed promising application potential in 41 examples.
Article
Chemistry, Multidisciplinary
Chaolumen Bai, Bao Chao, Tegshi Muschin, Agula Bao, Menghe Baiyin, Dan Liu, Yong-Sheng Bao
Summary: This study reports the regioselective cross-coupling reactions in the o-methyl benzaldehyde frameworks using palladium catalysis, K2S2O8 or [F+] reagents as oxidants, and unactivated arenes as substrates/solvents. The regiospecificity is controlled by [5,6]-fused or [6,5]-fused palladacycle intermediates formed from Pd-chelation with specific transient directing groups and C-H activations.
CHEMICAL COMMUNICATIONS
(2021)
Article
Chemistry, Multidisciplinary
Che-Sheng Hsu, Carlos R. Goncalves, Veronica Tona, Amandine Pons, Marcel Kaiser, Nuno Maulide
Summary: The article presents a method of synthesizing amine compounds using highly electron-deficient iminium ions and highlights its broad applicability through a specific case study.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Miran Lemmerer, Margaux Riomet, Ricardo Meyrelles, Boris Maryasin, Leticia Gonzalez, Nuno Maulide
Summary: This study presents a novel direct C-C coupling process that combines Michael acceptors and Eschenmoser's salt without the need for Lewis acid catalyst. The underlying mechanism was revealed through a combination of kinetic, isotopic labeling experiments, and computational investigations, highlighting the significant role of HFIP as a superior mediator for proton-transfer events and the decisive role of the halide counterion.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Organic
Miryam Pastor, Marie Vayer, Harald Weinstabl, Nuno Maulide
Summary: The study introduces a general electrochemical method for accessing unsymmetrical 3,3-disubstituted oxindoles by direct C-H functionalization, with the oxindole fragment acting as an electrophile. This Umpolung approach eliminates the need for stoichiometric oxidants and operates under mild, environmentally friendly conditions. Importantly, it enables functionalization of these scaffolds via C-O bonds, and can be extended to C-C or C-N bond formation.
JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Organic
Marie Vayer, Miryam Pastor, Christiane Kofink, Nuno Maulide
Summary: An unexpected rearrangement of 3-hydroxyoxindoles into benzoxazinones using electrochemistry was reported in this study. The reaction proceeds under mild and environmentally friendly conditions, with the benzoxazinone products obtained in moderate to excellent yields. Mechanistic experiments suggest the involvement of a peroxide intermediate.
Article
Chemistry, Multidisciplinary
Miran Lemmerer, Haoqi Zhang, Anthony J. Fernandes, Tobias Fischer, Marianne Miesskes, Yi Xiao, Nuno Maulide
Summary: Herein, we present a method for the synthesis of alpha-aryl acrylamides through polar S-to-C aryl migrations induced by a Lewis basic organocatalyst. This polar process allows subsequent elimination reactions, leading to a formal aryl/hydrogen exchange, including SO2 extrusion. The reaction is selective for electron-deficient aromatic groups and can tolerate a variety of substituents on nitrogen and in the beta-position, providing useful building blocks for further transformations.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Nuno Maulide, Boris Maryasin, Phillip S. Grant, Jeremy Merad, Tobias Stopka, Juliette Sabbatani, Ricardo Meyrelles, Alexander Preinfalk, Leticia Gonzalez
Summary: This paper reports a novel stereodivergent carbonyl olefination method using thiouronium ylides as olefination reagents. It can selectively convert aldehydes into Z-alkenes with high stereoselectivity and broad substrate scope. Additionally, it was discovered that N-tosylimines can also efficiently produce E-alkenes.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Multidisciplinary
Minghao Feng, Roberto Tinelli, Ricardo Meyrelles, Leticia Gonzalez, Boris Maryasin, Nuno Maulide
Summary: This study reports a practical method for the synthesis of alpha-amino acid derivatives via direct hydrative amination of activated alkynes using sulfinamides as the nitrogen source under mild conditions. Computational studies suggest that the reaction is enabled by a new type of sulfonium [2,3]-sigmatropic rearrangement.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Minghao Feng, Anthony J. J. Fernandes, Ana Sirvent, Eleonora Spinozzi, Saad Shaaban, Nuno Maulide
Summary: We present a simple method for the direct amination of unfunctionalized, native carbonyls (amides and ketones) by transferring a free amino group (NH2) from a commercially available nitrogen source. Mild conditions enable the production of primary a-amino carbonyls, allowing for diverse in situ functionalization reactions, such as peptide coupling and Pictet-Spengler cyclization, that take advantage of the presence of the unprotected primary amine.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Organic
Nuno Maulide, Irmgard Tiefenbrunner, Bogdan R. Brutiu, Tobias Stopka
Summary: We have developed an isothiouronium salt reagent for the straightforward synthesis of cyanomethyl thioesters with excellent functional group tolerance and without the need for thiols. Furthermore, we demonstrate that the obtained products can be used for amide synthesis in either a two-step or one-pot approach.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Phillip S. Grant, Ricardo Meyrelles, Oliver Gajsek, Gerhard Niederacher, Boris Maryasin, Nuno Maulide
Summary: Cationic cyclopropanation is a rare but important biosynthetic pathway involving the formation of a new sigma-C-C bond through the elimination of carbocations. Despite the historical influence of bioinspired synthetic chemistry, cationic cyclopropanation has not been widely used due to the preference of carbocations for competing elimination pathways. In this study, we conducted a synthetic and computational investigation of cationic cyclopropanation using 6,8-cycloeudesmanes as a platform, and successfully applied it to the synthesis of complex cyclopropanes.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Minghao Feng, Anthony J. Fernandes, Ricardo Meyrelles, Nuno Maulide
Summary: We report a new method for preparing chiral α-amino amides by directly aminating amides using chiral sulfinamides. This method involves a [2,3]-sigmatropic rearrangement of a crucial sulfonium intermediate. Quantum chemical calculations provide predictive insights into the important E/Z selectivity of the amino-vinyloxy-sulfonium species.
Article
Chemistry, Multidisciplinary
Miran Lemmerer, Nuno Maulide
Summary: The combination of Lewis bases with alpha, beta-unsaturated carbonyls enables the in-situ generation of enolates, eliminating the need for strong Bronsted bases. This approach has been widely employed in arylation reactions in various contexts. This conceptual article provides an overview of the developed strategies, highlighting their features.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Organic
Alexander Garay-Talero, Tales A. C. Goulart, Rafael D. C. Gallo, Roberto do C. Pinheiro, Catalina Hoyos-Orozco, Igor D. Jurberg, Diego Gamba-Sanchez
Summary: An aza-Robinson annulation strategy involving NaOEt-catalyzed conjugate addition of cyclic imides onto vinyl ketones and TfOH-mediated intramolecular aldol condensation has been developed for the synthesis of densely functionalized fused bicyclic amides. The potential use of these amides in the synthesis of alkaloids has been demonstrated by the conversion of appropriate precursors to (+/-)-coniceine and quinolizidine in two additional steps, achieving overall yields of 40% and 44%, respectively.
Article
Chemistry, Multidisciplinary
David Just, Carlos R. Goncalves, Uros Vezonik, Daniel Kaiser, Nuno Maulide
Summary: A simple method for the direct formation of aminolactones from unactivated alkenes has been reported in this study, filling the gap in this field. The method utilizes cheap and readily available reactants, and exhibits excellent functional group tolerance and chemoselectivity. The synthetic versatility of the products has been demonstrated through a range of transformations.
Article
Education, Scientific Disciplines
Anja Lembens, Gerda Heinzle, Alexandra Tepla, Nuno Maulide, Alexander Preinfalk, Daniel Kaiser, Philipp Spitzer
Summary: This paper introduces the SpottingScience project, which uses digital learning environments to educate passers-by and secondary school students about green chemistry. These learning environments can be accessed through QR codes in public spaces at the University of Vienna campus, providing a more interactive way to understand the importance of green chemistry in everyday life.
CHEMISTRY TEACHER INTERNATIONAL
(2022)