Article
Chemistry, Multidisciplinary
Serhii Medvedko, Markus Stroebele, J. Philipp Wagner
Summary: Thiourea S-oxides are formal analogs of diamino-substituted Criegee intermediates, but their preparation is challenging. The oxidation of thioureas typically leads to desulfurized products. However, peracid mediated oxidation of thiourea S-oxides has a lower reaction barrier compared to thiourea itself. Bulky substituents and protic solvents can suppress overoxidation reactivity associated with strong pi-donation. Sterically encumbered thiourea S-oxides were successfully prepared in isolated yields of 35-40%. These S-oxides are stable in the solid state and alcoholic solutions, but decompose rapidly in aprotic solvents. The importance of hydrogen bonding in stabilizing the amino-substituted C=S+-O- moiety was confirmed by X-ray crystallography.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Inorganic & Nuclear
Silene Engbers, Evgeniya A. Trifonova, Kristopher M. Hess, Folkert Vries, Johannes E. M. N. Klein
Summary: This study reports a novel Au(III)-OH complex with unique steric hindrance, which shows no reactivity with phosphines. The steric encumbrance sets this example apart from known Au(III)-OH complexes, providing a new perspective for studying the OAT mechanism.
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Simon Sengupta, Philipp Schueler, Phil Liebing, Matthias Westerhausen
Summary: Magnesium and calcium are too inert to directly deprotonate amines, so alternative strategies are needed for the synthesis of bulky amides. N-bound trialkylsilyl groups have been used to facilitate metalation reactions. In situ Grignard reagent formation in THF with magnesium or calcium, hydryl halide, and imine allows the synthesis of amides with bulky silyl-free substituents. Ball milling protocols may lead to competing side reactions like aza-pinacol coupling reactions. Calcium is a better choice for in situ Grignard reagent formation and subsequent addition to imines, while heavier alkaline-earth metals strontium and barium are less selective, leading to competitive aza-pinacol coupling reactions. Solid-state molecular structures of [(Et2O)Mg(N(Ph)(CHPh2)(2)] and [(Et2O)(2)Ca(N(Ph)(CHPh2)(2)] have been determined.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Yufei Wang, Amanda A. Chen, Krista P. Balto, Yu Xie, Joshua S. Figueroa, Tod A. Pascal, Andrea R. Tao
Summary: Organic ligands play a critical role in determining the physiochemical properties of inorganic nanocrystals. A new approach based on ligand anchoring groups has been developed to achieve precise surface modification of nanocrystals.
Article
Chemistry, Multidisciplinary
Zeus A. De los Santos, Ciaran C. Lynch, Christian Wolf
Summary: A steric encumbered aminoborane sensor was introduced for quantitative stereochemical analysis, showing high accuracy and sensitivity. The sensor utilized a rigid structure and circular dichroism signals to achieve comprehensive analysis of absolute configuration, enantiomeric composition, and concentration. It was proven effective in the analysis of crude asymmetric reaction mixtures, offering advantages over traditional methods in terms of sensitivity and compatibility with high-throughput experimentation and automation.
CHEMISTRY-A EUROPEAN JOURNAL
(2022)
Article
Chemistry, Inorganic & Nuclear
Rachel L. Meyer, Pere Miro, William W. Brennessel, Ellen M. Matson
Summary: The study reveals the potential of functionalized POV-alkoxide clusters in mimicking heterogeneous metal oxide catalysts through activation and reduction of oxygen. The use of the calix motif restricts O-2 activation, enabling comparison of reactivity with nonfunctionalized POV-alkoxides.
INORGANIC CHEMISTRY
(2021)
Article
Chemistry, Organic
Francisco Garnes-Portoles, Sergio Sanz-Navarro, Jordi Ballesteros-Soberanas, Ana Collado-Perez, Jorge Sanchez-Quesada, Estela Espinos-Ferri, Antonio Leyva-Perez
Summary: In this study, two new phosphine ligands were successfully synthesized using indomuscone as a scaffold, and they showed enhanced electronic and steric properties. These new phosphine ligands exhibited excellent catalytic activities in palladium-catalyzed reactions.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Inorganic & Nuclear
Craig S. Day, Stephanie J. Ton, Ryan T. McGuire, Cina Foroutan-Nejad, Ruben Martin
Summary: Here, we report the synthesis of sterically encumbered dialkylnickel(II) complexes bearing 2,9-dimethyl-1,10phenanthroline ligands. A comparison with their unsubstituted analogues reveals significant distortions in their molecular structures, as observed through X-ray crystallography and theoretical calculations. Eyring plots, along with stoichiometric and photoexcitation studies, demonstrate that these sterically encumbered dialkylnickel(II) complexes allow for facile C(sp3)-C(sp3) reductive elimination, providing insights into Ni catalysis.
Article
Chemistry, Physical
Philipp Neigenfind, Daniel Knyszek, Jens Handelmann, Viktoria H. Gessner
Summary: This study successfully synthesized bulky, ortho-substituted triarylamines using ylide-substituted phosphines (YPhos) with high yields at low temperatures, providing a convenient and mild method for the synthesis of organic electronic materials.
CATALYSIS SCIENCE & TECHNOLOGY
(2022)
Article
Chemistry, Multidisciplinary
T. Prapakaran, S. Kuppuswamy, Ramaswamy Murugavel
Summary: A sterically encumbered 2,6-di-tert-butylphenyl phosphate has been synthesized and its supramolecular aggregation behavior, as well as the structures of resulting adducts, were investigated.
Article
Chemistry, Inorganic & Nuclear
Dooyoung Kim, Michael C. Rosko, Vinh Q. Dang, Felix N. Castellano, Thomas S. Teets
Summary: One of the main challenges in developing effective copper(I) photosensitizers is their short excited-state lifetimes. In this study, steric modifications were introduced to improve the excited-state lifetimes of these complexes, and the effects of alkyl groups on the excited-state dynamics were investigated. The results revealed that sterically encumbered complexes exhibited significantly longer excited-state lifetimes compared to the unsubstituted complex.
INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Samrat Sahu, Ganesh Karan, Lisa Roy, Modhu Sudan Maji
Summary: A diastereoselective allylation of N-tert-butane sulfinyl alpha-iminoesters using allylboronic acids has been developed for obtaining optically active non-proteinogenic alpha-amino acid precursors with high yields and diastereoselectivities. This protocol offers gram-scale synthesis, broad functional group tolerance, excellent stereodivergence, post-synthetic modifications, and easy removal of the chiral auxiliary, making it applicable to various amino acids and short peptides for incorporation of these precursors at the N-terminal position.
Article
Chemistry, Inorganic & Nuclear
Jack A. Killion, William T. Darrow, Marshall R. Brennan, Clare A. Leahy, Alison R. Fout
Summary: A highly efficient catalyst was developed for the Kumada coupling of aryl Grignard reagents to sterically encumbered alkyl halides. The catalyst showed excellent substrate scope and functional group tolerance.
Article
Chemistry, Organic
Jinshan Li, Saimei Liu, Rong Zhong, Yaqi Yang, Yuru He, Jianguo Yang, Yongmin Ma, Zhiming Wang
Summary: An efficient method has been developed for the reversal of regioselectivity in the nucleophilic introduction of difluorinated carbanion into alpha, beta-enones via silylium catalysis. The strong electron-withdrawing properties and bulky substituents of in situ-generated silyl triflic imide catalyst play a key role in the successful 1,4-addition reaction. The synthetic utility of this method is demonstrated by its further application in the one-pot synthesis of 2,4,6-triarylsubstituted 3-fluoropyridines.
Article
Chemistry, Inorganic & Nuclear
Aaron A. Ruch, Matthew C. Ellison, John K. Nguyen, Fanji Kong, Sachin Handa, Vladimir N. Nesterov, LeGrande M. Slaughter
Summary: The study synthesized sterically encumbered gold(I) acyclic diaminocarbene (ADC) complexes with different ligands and found that the bulky biaryl/terphenyl groups strongly influence product selectivity in gold-catalyzed reactions. The research also revealed how large aryl groups impact reaction mechanisms.
Article
Chemistry, Multidisciplinary
Johannes E. Erchinger, Reece Hoogesteger, Ranjini Laskar, Subhabrata Dutta, Carla Huempel, Debanjan Rana, Constantin G. Daniliuc, Frank Glorius
Summary: This article presents a new synthetic method that utilizes a photosensitizer to react sulfur fluoride compounds with alkenes, resulting in protected beta-amino sulfonyl fluorides. This method can be used to synthesize peptido sulfonyl fluorides, beta-ammonium sulfonates, and beta-sultams relevant in medicinal chemistry.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Guangying Tan, Fritz Paulus, Alessia Petti, Maxim-Aleksa Wiethoff, Anna Lauer, Constantin Daniliuc, Frank Glorius
Summary: A novel radical relay 1,4-carboimination between two distinct olefins with alkyl carboxylic acid-derived bifunctional oxime esters was achieved via energy transfer catalysis. The reaction showed high chemo- and regioselectivity, forming multiple C-C and C-N bonds in a single operation. This mild and metal-free method exhibited a broad substrate scope and excellent tolerance of sensitive functional groups, providing easy access to structurally diverse 1,4-carboiminated products. Furthermore, the obtained imines could be readily converted into valuable biologically relevant free gamma-amino acids.
Article
Chemistry, Organic
Dawod Yousif, Luca Vaghi, Constantin G. Daniliuc, Riccardo Po, Antonio Papagni, Fabio Rizzo
Summary: The regioselective nitration of 9,9'-spirobifluorene under mild conditions is reported for the first time using Menke's and Crivello's conditions. The optimized protocol yields 2-nitro and 2,2'-dinitro-9,9'-spirobifluorene in 79% and 95% yield, respectively, and for the first time, 2,2',7-trinitro-9,9'-spirobifluorene with a yield of 66%. Additionally, the role of dinitrate salt in Crivello's protocol has now been clarified, opening up new possibilities in the preparation of functional materials.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Till Drennhaus, Dirk Leifert, Jessika Lammert, Jan Philipp Drennhaus, Klaus Bergander, Constantin G. Daniliuc, Armido Studer
Summary: In this study, enantioenriched chiral indoles were synthesized through a mild and efficient radical cascade reaction using a chiral copper-bisoxazoline complex. The targeted 2-fluoroalkylated 3-(alpha-cyanobenzy-lated) indoles were accessed with excellent enantioselectivity and good yields. Mechanistic studies revealed a negative nonlinear effect which explained the stereochemical outcome. The enantioenriched 3-(alpha-cyanobenzylated) indoles demonstrated scalability and potential utility as hubs for chiral tryptamines, indole-3-acetic acid derivatives, and triarylmethanes, and a formal synthesis of a natural product analogue was disclosed.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Zhe Wang, Nick Wierich, Jingjing Zhang, Constantin G. Daniliuc, Armido Studer
Summary: In this study, a method for direct generation of alkyl radicals from alkylboronic pinacol esters (APEs) through reaction with aminyl radicals is reported. Aminyl radicals are readily generated by visible-light-induced homolytic cleavage of the N-N bond in N-nitrosamines, and C radical generation occurs through nucleohomolytic substitution at boron. As an application, the highly efficient photochemical radical alkyloximation of alkenes with APEs and N-nitrosamines under mild conditions is presented. Various primary, secondary, and tertiary APEs can be used in this scalable transformation.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Roman Kleinmans, Subhabrata Dutta, Kristers Ozols, Huiling Shao, Felix Schafer, Rebecca E. Thielemann, Hok Tsun Chan, Constantin G. Daniliuc, Kendall N. Houk, Frank Glorius
Summary: The ortho-selective intermolecular photocycloaddition of bicyclic aza-arenes is reported, utilizing a strain-release approach. This reaction enables the construction of C-(sp(3))-rich bicyclo-[2.1.1]-hexanes directly connected to N-heteroarenes. Photophysical experiments and DFT calculations reveal the mechanism of this selective intermolecular photocycloaddition.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Alena I. Siutkina, Svetlana Kalinina, Rongfang Liu, Laura H. Heitman, Anna Junker, Constantin G. Daniliuc, Dmitrii V. Kalinin
Summary: We report the microwave-assisted synthesis of previously unreported 6-methoxy-5,6-dihydro-5-azapurines, which have a promising purinelike scaffold for drug discovery. The method is simple and fast, using easily accessible reagents such as trimethyl orthoformate, acetic acid, and aminotriazole-derived N,N'-disubstituted formamidines. Preliminary biological evaluation showed that the synthesized 6-methoxy-5,6-dihydro-5-azapurines dose-dependently reduce the viability of HepG2 and A549 cancer cells with little to no influence on five tested purinergic receptors.
Article
Chemistry, Physical
Dasharath Kondhare, Xenia Heddinga, Simone Budow-Busse, Constantin Daniliuc, Frank Seela
Summary: The single-crystal X-ray structure of 5-aza-7-deaza-7-iodoguanine 2'-C-methylribonucleoside 1 is described, which was synthesized through stereoselective nucleobase anion glycosylation and subsequent deprotection. The CD-spectrum analysis of 1 revealed the significant impact of the iodo substituent on the molecule. A dye conjugate was generated by Suzuki-Miyaura cross-coupling of 1 with pyrene boronic acid, showing solvent dependent exciplex fluorescence.
JOURNAL OF MOLECULAR STRUCTURE
(2023)
Article
Chemistry, Multidisciplinary
Fritz Paulus, Colin Stein, Corinna Heusel, Tobias J. Stoffels, Constantin G. Daniliuc, Frank Glorius
Summary: In this study, a novel three-component 1,2,5-trifunctionalization reaction driven by visible light energy transfer-catalysis was reported. Selective installation of three different functional groups was achieved in one step by utilizing imine-based bifunctional reagents and two distinct alkenes. Mechanistic studies and downstream modifications demonstrated the synthetic utility of the obtained products.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Huamin Wang, Johannes E. Erchinger, Madina Lenz, Subhabrata Dutta, Constantin G. Daniliuc, Frank Glorius
Summary: This study presents a photoredox strategy that enables the high regio- and syn-selective difunctionalization of bicyclo[1.1.0]-butanes (BCBs). By cleaving C-S sigma bonds, sulfur-alkynylation, -alkenylation, and -allylation of BCBs can be achieved under mild conditions, demonstrating the generality of this approach.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Organic
Shyam Kumar Banjare, Dirk Leifert, Frauke Weidlich, Constantin G. Daniliuc, Fatmah A. Alasmary, Armido Studer
Summary: An oxidative radical cascade addition cyclization approach using eco-friendly iron catalysis and inexpensive TBHP as the oxidant has been developed for the synthesis of quinoline-based p-extended polyheterocyclic compounds. This method allows the preparation of quinolines that are p-conjugated with an additional heteroarene moiety in a single sequence.
Article
Chemistry, Multidisciplinary
Lukas Schifferer, Leon Hoppmann, Robin Groeters, Christian Mueck-Lichtenfeld, Constantin G. Daniliuc, Olga Garcia Mancheno
Summary: A solvent-dependent, divergent synthesis of highly functionalized N,S-heterocycles, containing thiazoline and isoquinuclidine or tetrahydroisoquinoline scaffolds, has been reported. This synthesis involves cyclization reactions of isoquinolinium 1,4-zwitterionic thiolates and shows robustness and applicability as demonstrated by efficient upscaling of the reaction and derivatization of the resulting products.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Till Drennhaus, Dirk Leifert, Jessika Lammert, Jan Philipp Drennhaus, Klaus Bergander, Constantin G. Daniliuc, Armido Studer
Summary: Enantioenriched chiral indoles were synthesized through a mild and efficient radical cascade reaction. The targeted indoles were accessed by stereochemical control using a chiral copper-bisoxazoline complex. The method demonstrated excellent enantioselectivity and good yields, and the mechanism was elucidated through mechanistic studies.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Angela Mesias-Salazar, Rene S. Rojas, Fernando Carrillo-Hermosilla, Javier Martinez, Antonio Antinolo, Oleksandra S. Trofymchuk, Fabiane M. Nachtigall, Leonardo S. Santos, Constantin G. Daniliuc
Summary: This study presents the synthesis and characterization of a new family of one-component catalysts based on guanidinium salts, which are used for the synthesis of cyclic carbonates. The results demonstrate that these catalysts have good conversion rates and can operate effectively at moderate pressures and temperatures.
NEW JOURNAL OF CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Timo Stuenkel, Kathrin Siebold, Daichi Okumatsu, Kazuki Murata, Louise Ruyet, Constantin G. Daniliuc, Ryan Gilmour
Summary: The regio- and enantio-selective dearomatization of phenols has been achieved using I(i)/I(iii) catalysis enabled fluorination. The reaction is highly selective and efficient, offering great potential in the field of hydroxylation chemistry.
