Article
Chemistry, Physical
Maxwell G. Holl, Tristan H. Lambert
Summary: The ring-opening carbonyl-olefin metathesis of cyclobutenes can be used to synthesize a variety of aldehydes, and the bistrifluoroacetic acid salt of 2,3-diazabicyclo[2.2.2]octane is an efficient catalyst for promoting these reactions.
Article
Chemistry, Multidisciplinary
Huai-Ri Sun, Lan Yang, Yu Li, Le Yu, Bo-Bo Gou, Atif Sharif, Qing-Song Jian, Jie Chen, Ling Zhou
Summary: A chiral phosphoric acid was used as a catalyst for the enantioselective [2 + 2] cycloaddition reaction between alkynylindols or alkynylnaphthols and quinones. The reaction produced a class of functionalized cyclobutenes with high yields and excellent diastereo- and enantioselectivities. Mechanistic studies revealed the involvement of dearomatization of indole or naphthol and intramolecular Michael addition in the reaction, while preventing competitive [2 + 3] cycloaddition. During the transformation of the product, an interesting conversion from central to axial chirality was achieved through a rearrangement process.
SCIENCE CHINA-CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Wanlong Xiao, Lichao Ning, Shuang Xin, Shunxi Dong, Xiaohua Liu, Xiaoming Feng
Summary: An efficient catalytic asymmetric [2+2] cycloaddition of allenyl imide and mono- or disubstituted alkenes has been developed. The use of chiral magnesium(II) complex of N,N'-dioxide allows for high yield and excellent enantioselectivity of axially chiral cyclobutenes and four-membered ring-containing spirocycles. This methodology can also be applied for the late-stage modification of biologically active molecules.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Jia-Yin Wang, Chen-Long Li, Ting Xu, Meng-Fan Li, Wen-Juan Hao, Shu-Jiang Tu, Jianyi Wang, Guigen Li, Zhi-Xiang Yu, Bo Jiang
Summary: The synthesis of 6-6-4 and 6-4 carbocyclic scaffolds with a chiral quaternary center at the bridgehead position was successfully achieved through Pd(II)/chiral N,N'-disulfonyl bisimidazoline (Bim) ligand-catalyzed reactions, with high chemo-, regio- and enantio-selectivities. The design of a chiral Bim ligand, utilized for catalyzing asymmetric 1,4-conjugate addition reaction, showed promising catalytic performance.
CHINESE JOURNAL OF CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Jianfeng Jiang, Xia Wang, Shengping Liu, Sichen Zhang, Binmiao Yang, Yu Zhao, Shenci Lu
Summary: We report an unprecedented gold and oxidative NHC relay catalysis for highly enantioselective cascade annulation between readily available alpha-amino-ynones with enals. This method utilizes in situ-generated pyrrolin-4-ones as a novel and versatile synthon, reacting with alpha,beta-unsaturated acylazolium intermediates generated from enals by oxidative NHC catalysis to produce pyrrole-fused lactones in high yield and excellent enantioselectivity. The utility of the lactone products is demonstrated by their facile conversion to densely functionalized pyrroles and pyrrolin-4-ones with high yields and excellent stereopurity.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Christopher J. Smedley, Marie-Claire Giel, Thomas Fallon, John E. Moses
Summary: In this study, we present a method for synthesizing a stable precursor to ethene-1,1-disulfonyl difluoride (EDSF) and demonstrate its use in the preparation of various functionalized 4-membered ring carbocycles. These carbocycles are important structural motifs found in bioactive natural products and pharmaceutically relevant small molecules. We also show that the novel cyclobutene cores can be diversified through selective click chemistry, yielding high-efficiency sulfonate ester products. DFT calculations provide mechanistic insights into the reaction pathway.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Guoqiang Yang, Ya-Ming Ke, Yu Zhao
Summary: A gold and palladium sequential catalysis system has been reported for efficient and enantioselective access to furan-fused nine-membered heterocycles. In this one-pot procedure, easily accessible enynamides undergo cyclization to generate azadienes in situ, which then participate in enantioselective formal [5+4] cycloaddition with vinyl ethylene carbonates. Furthermore, conformation-controlled highly diastereoselective derivatizations of these medium-sized rings, coupled with oxidative furan cleavage, have enabled the access to diverse densely-functionalized nine-membered lactams.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Tatiana Suarez-Rodriguez, angel L. Suarez-Sobrino, Alfredo Ballesteros
Summary: The Gold(I)-catalyzed formal [4+2] cycloaddition of O-aryl ynol ethers 1 and enol ethers 2 results in chromene derivatives with good yields under mild conditions. The reaction is completely regio- and stereoselective, and versatile for different reactants, including silyl enol ethers. Experimental results support a proposed mechanism involving the selective addition of the enol ether to the alkyne gold activated complex followed by an intramolecular aromatic electrophilic substitution, leading to the formation of a cationic oxonium intermediate prior to the aromatic substitution. This reaction introduces a new route to the chromene core.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
Article
Chemistry, Multidisciplinary
Jing Liu, Yusheng Yang, Weiming Shi, Zhi-Xiang Yu
Summary: We present computational evidence for a metalla-Claisen rearrangement (MCR) in the gold-catalyzed [4+2] cycloaddition reaction of yne-dienes. The reaction proceeds through exo cyclopropanation, followed by MCR and reductive elimination. The presence of a cyclopropane moiety formed in the initial step greatly facilitates the MCR process. Additionally, we explore the significance of the combination of tether group and terminal substituent on alkyne in the yne-diene substrates. We also investigate whether an MCR mechanism is involved in the rhodium-catalyzed [4+2] reaction of yne-dienes. These findings and insights represent a significant advancement in the field of catalysis.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Xufei Yan, Yulei Zhu, Ying Xia
Summary: We report a nickel catalyst system using a modified SPINOL ligand which enables the coupling of tertiary cyclobutenols and arylboroxines in an enantioconvergent manner, resulting in cyclobutenes with an all-carbon quaternary stereocenter in good yields (up to 84% yield) and excellent enantioselectivities (up to > 99% ee). The catalytic system can also be used in the kinetic resolution of cyclobutenols, producing enantioenriched tertiary cyclobutenols with an s factor of up to >200. The reaction utilizes free hydroxyl groups as leaving groups without additional activation, while preserving the strained ring structure. Preliminary mechanistic studies reveal that the different reactivities of the two enantiomers are key to the controllable enantioconvergent and kinetic resolution processes.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Organic
Hailing Yin, Yunjun Wu, Yifan Jiang, Meifang Wang, Shaoyin Wang
Summary: A metal-free and environmentally friendly approach to cyclohepta[b]indole and furo[3,4-b]carbazole frameworks via a three-component reaction from indoles, tertiary propargylic alcohols, and activated alkynes is described. The probable mechanism was proposed based on the isolation and characterization of a key intermediate. Gram-scale reaction and product derivatizations were performed to demonstrate the practicality of the developed methodology.
Review
Chemistry, Organic
Shashank P. Sancheti, Nitin T. Patil
Summary: The unique nature of gold carbene and its synchronous counterpart gold-stabilized carbocation result in a non-canonical reactivity profile distinct from other transition metal carbenes. Reactions of gold carbene with alkyne sponsor products exhibit diverse and unexpected outcomes, with multiple proposed pathways due to the difficulty in distinguishing between vinyl gold carbene and beta-gold vinyl cation reactivities.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Inorganic & Nuclear
Qing Sun, Tian-Yu Deng, Jia-Jie Chen, Jia-Yi Liu, Xin Lu, Zhi-Xia Zhang, Jin-Heng Li
Summary: The mechanism of Au(i)-catalyzed intermolecular annulation of 2-(1-alkynyl)-2-alken-1-one with N-allenamide has been elucidated using DFT. The key intermediate, a gold all-carbon 1,3-dipole species, is more reactive than the gold allylic carbocation. The influence of ligands and substituents has been analyzed.
DALTON TRANSACTIONS
(2022)
Article
Chemistry, Multidisciplinary
Morgane de Robichon, Thilo Kratz, Frederike Beyer, Julian Zuber, Christian Merten, Thorsten Bach
Summary: Substituted bicyclo[1.1.0]butanes add enantioselectively to 2(1H)-quinolones upon irradiation, leading to the formation of products with a chiral bicyclo[2.1.1]hexane skeleton. A two-point hydrogen bond between the quinolone and the template is responsible for stereocontrol in the photocycloaddition reaction. The chiral template can be recovered and reused, and sensitization is a suitable tool for performing the reaction with visible light.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Organic
Malgorzata Z. Makos, Marek Freindorf, Yunwen Tao, Elfi Kraka
Summary: This study investigates the mechanism of [NHC]Au(I)-catalyzed hydroalkoxylation of allene, revealing that the catalyst facilitates the reaction through a two-step mechanism. Results show that the π-Au C=C interactions in the products are stronger than those in the reactants, contributing to the exothermic nature of the reaction.
JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Chenxiao Qi, Guillaume Force, Vincent Gandon, David Leboeuf
Summary: A novel method for haloamidation is introduced in this paper, providing new building blocks for drug discovery. This method overcomes some limitations of traditional reactions and the reaction mechanism is deeply studied, which is expected to promote the development of more complex transformations in this field.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Organic
Shengdong Wang, Guillaume Force, Jean-Francois Carpentier, Yann Sarazin, Christophe Bour, Vincent Gandon, David Leboeuf
Summary: A modular one-pot synthesis of 9,10-dihydroacridine frameworks was achieved through a reaction sequence involving selective ortho-C alkenylation of diarylamines with aryl alkynes followed by intramolecular hydroarylation. The combination of hexafluoroisopropanol and triflimide as catalysts played a crucial role in triggering the whole process.
Article
Chemistry, Applied
Lucile Marin, Soufyan Jerhaoui, Emilie Kolodziej, Regis Guillot, Vincent Gandon, Francoise Colobert, Emmanuelle Schulz, Joanna Wencel-Delord, David Leboeuf
Summary: A stereoselective aza-Piancatelli reaction has been developed for the synthesis of 4-aminocyclopentenones, using chiral o-sulfinyl anilines as chiral inductors. The targeted products can be obtained in good to excellent yields, with high drs up to >95:5 depending on the furan substitution pattern.
ADVANCED SYNTHESIS & CATALYSIS
(2021)
Article
Chemistry, Multidisciplinary
Guillaume Force, Anna Perfetto, Robert J. Mayer, Ilaria Ciofini, David Leboeuf
Summary: A new strategy employing a mixed anhydride with a pentafluorophenyl group is described for the convenient synthesis of macrolactones and other products. Kinetic studies and DFT computations were used to rationalize the reactivity of the pentafluorophenyl group in the reactions.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Allegra Franchino, Alex Marti, Antonio M. Echavarren
Summary: A new strategy for enantioselective transition-metal catalysis is presented, where precise positioning of chiral counteranions responsible for asymmetric induction is achieved by placing a H-bond donor on the ligand of a cationic complex. This paradigm was successfully implemented in 5-exo-dig and 6-endo-dig cyclizations of 1,6-enynes, allowing the use of chiral anions in Au(I)-catalyzed reactions of challenging alkyne substrates. Experimental evidence confirmed the crucial H-bonding interaction at the heart of the catalytic system.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Physical
Ulysse Caniparoli, Imma Escofet, Antonio M. Echavarren
Summary: Planar chiral monodentate 1,3-disubstituted ferrocene phosphines inspired by JohnPhos-type ligands have been synthesized and applied for the enantioselective gold(I) catalyzed [4 + 2] cycloaddition of 1,6-arylenynes. Computational studies elucidated the working mode of the catalyst, involving attractive noncovalent interactions that induce the folding of the substrate in the chiral environment of the ligand.
Article
Chemistry, Physical
Marie Vayer, Shaofei Zhang, Joseph Moran, David Lebaeuf
Summary: This article describes a general method for the reduction of styrene oxides, which is both linear-selective and compatible with strongly electronically deactivated substrates. The reaction is user-friendly and does not require special reagents or atmosphere conditions.
Article
Chemistry, Physical
Marie Vayer, Robert J. Mayer, Joseph Moran, David Leboeuf
Summary: We demonstrate a promoter system featuring triflic acid and hexafluoroisopropanol that enables the direct construction of trifluoromethylated all-carbon quaternary centers, significantly expanding the scope of hydroarylation of unactivated styrenes and providing a straightforward approach to trifluoromethylated diarylalkanes of interest.
Article
Chemistry, Multidisciplinary
Valentyn Pozhydaiev, Marie Vayer, Claire Fave, Joseph Moran, David Leboeuf
Summary: We report a new one-pot protocol for the synthesis of beta-arylethylamines, which allows the direct entry to unprotected compounds with remarkable functional group tolerance. This method involves the 1,2-aminoarylation of alkenes using hydroxylammonium triflate salts and (hetero)arenes. The combination of hexafluoroisopropanol as a solvent and an iron(II) catalyst is crucial for the synthesis of nitrogen-containing molecules.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Tommaso Bortolato, Gianluca Simionato, Marie Vayer, Cristian Rosso, Lorenzo Paoloni, Edmondo M. Benetti, Andrea Sartorel, David Leboeuf, Luca Dell'Amico
Summary: This study reports the design and characterization of 9-aryl dihydroacridines (9ADA) and 12-aryl dihydrobenzoacridines (12ADBA) as strong reducing organic photocatalysts. These photocatalysts exhibit locally excited or charge-transfer excited states, and can perform photoredox defunctionalization processes and atom transfer radical polymerization under visible light. They also feature a catalytic multisite proton-coupled electron transfer (MS-PCET) mechanism, enabling the reduction of redox-inert substrates under single-photon excitation. These new photocatalysts are expected to open new mechanistic pathways in the field of photocatalysis.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Andrea Cataffo, Miguel Pena-Lopez, Riccardo Pedrazzani, Antonio M. Echavarren
Summary: This study presents two classes of stereoselective cyclizations using a chiral auxiliary approach. The first class involves the stereoselective cascade cyclization of 1,5-enynes using Oppolzer camphorsultam as chiral auxiliary, leading to the synthesis of enantioenriched spirocyclic ketones. The second class focuses on the stereoselective alkoxycyclization of 1,6-enynes mediated by Evans-type oxazolidinone, resulting in the formation of enantioenriched beta-tetralones after removal of the auxiliary.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Physical
Alex Marti, Gala Ogalla, Antonio M. Echavarren
Summary: The enantioselective reaction of 1,6-enynes with O-, N-, and C-nucleophiles has been achieved through matched ion pair gold(I) catalysis. The chiral gold(I) cation and anion are H-bonded through a urea group, leading to very high levels of enantiocontrol (>99:1 er) for a wide range of substrates. DFT studies highlight the importance of the H-bond donor group in anchoring the matched chiral cation- and anion-favoring additional noncovalent interactions.
Article
Chemistry, Multidisciplinary
Cyprien Muller, Filip Horky, Marie Vayer, Andrei Golushko, David Leboeuf, Joseph Moran
Summary: This paper describes a new variant of the oxa-Pictet-Spengler reaction using epoxide as a starting material, which greatly expands the scope and rate of the reaction. By using hexafluoroisopropanol as a solvent, the electrophile scope of the reaction includes ketone analogues, aliphatic aldehydes, and phenylacetyl aldehydes, and the nucleophile scope includes moderately electronically deactivated and highly substituted beta-phenylethanols. In addition, the products can be further modified in the same system by subsequent ring-opening, reductions, and intra- and intermolecular Friedel-Crafts reactions. Finally, the synthesis of drug analogues demonstrates the pharmacological relevance of the isochroman motif.
Article
Chemistry, Multidisciplinary
Eduardo Garcia-Padilla, Imma Escofet, Feliu Maseras, Antonio M. Echavarren
Summary: Through computational analysis, we have identified the dominant structures of the intermediates of gold(I)-catalyzed cyclizations of 1,5-enynes and 1,5-allenenes, including gold(I) cyclopropylcarbenes, endocyclic vinylgold complexes and previously unreported non-classical carbocationic minima. Cyclopropylcarbene structures are consistently favored as the most stable intermediates for all studied substitution patterns.
Article
Chemistry, Multidisciplinary
Nicolas Zeidan, Sergiu Bicic, Robert J. Mayer, David Leboeuf, Joseph Moran
Summary: This study demonstrates that HFIP greatly expands the scope of the Bronsted acid-catalyzed hydroarylation of enamides, and acts as a slow-release reservoir for the key cationic intermediate. The reaction is fast and practical, and can prevent the oligomerization of the substrate.
