Article
Chemistry, Multidisciplinary
Martin Berger, Davide Carboni, Paolo Melchiorre
Summary: The study presents the first catalytic enantioselective conjugate addition of allyl groups to alpha, beta-unsaturated aldehydes, utilizing the visible-light-excitation of chiral iminium ions to activate allyl silanes toward the formation of allylic radicals. This radical mechanism overcomes issues seen in traditional conjugate allylation processes and selectively installs prenyl fragments at the beta-carbon of enals.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Organic
Chuncheng Zou, Yanting Lv, Min Lu, Xin Li, Lei Zhang, Lei Yang, Zhen Liu, Yanxiong Ke, Gonghua Song, Jinxing Ye
Summary: This study reported regioselective and diastereodivergent asymmetric vinylogous Michael addition between beta-substituted-cyclohexenones and nitroalkenes using complementary chiral aminocatalysts. The reactions showed high enantio- and diastereoselectivities, with DFT calculations explaining the stereochemistry control through hydrogen-bonding interaction and steric hindrance effects. Additionally, the diverse configurations of the adducts led to enantioenriched spirocyclic ketones and cis-2-decalones with multiple chiral centers.
ORGANIC CHEMISTRY FRONTIERS
(2021)
Article
Chemistry, Applied
Jen-Yu Kuan, I-Ting Chen, Hsuan Lin, Jeng-Liang Han
Summary: We have developed a substrate-dependent, regio- and stereocontrolled diversity-oriented organocatalytic vinylogous Michael addition/cyclization cascade of 2-alkylidene indane-1,3-diones with enals, using secondary amines as the catalyst. This method allows for the selective synthesis of spiroindane-1,3-diones, tetrahydrofluoren-9-one derivatives, and benzofused oxabicyclo[3.3.1]nonanes. Plausible catalytic pathways have been proposed, and DFT calculations have clarified the mechanisms involved.
ADVANCED SYNTHESIS & CATALYSIS
(2023)
Article
Chemistry, Organic
Naruhiro Gondo, Koki Fujimura, Ryuichi Hyakutake, Yoshihiro Ueda, Takeo Kawabata
Summary: Asymmetric regioselective vinylogous aza-Morita-Baylis-Hillman reactions were conducted using organocatalysis. The reactions between 3-vinylcyclopentenone and various aldimines, in the presence of chiral pyrrolidinopyridine catalysts, yielded 7-adducts with high regioselectivity and moderate enantioselectivity.
TETRAHEDRON LETTERS
(2023)
Article
Chemistry, Organic
Jiahang Yan, Wenting Zhang, Qiaoqiao He, Jun Hou, Hongxin Zeng, Hongbo Wei, Weiqing Xie
Summary: This study presents a nickel-catalyzed asymmetric direct vinylogous Michael addition and a tandem catalytic asymmetric vinylogous Michael addition/intramolecular Michael addition, which provide efficient and selective routes to synthesize diverse organic compounds.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2022)
Article
Chemistry, Organic
Arijit Hazra, Raghunath Dey, Apoorv Kushwaha, T. J. Dhilip Kumar, Prabal Banerjee
Summary: For the first time, an organocatalytic enantioselective (3+3)-cycloaddition reaction of racemic cyclopropane carbaldehydes and aryl hydrazones has been demonstrated. Enantioenriched tetrahydropyridazines with an exocyclic double bond were obtained in moderate to good yields and with good to excellent enantiomeric excesses. Mechanistic investigations suggested a matched/mismatched kinetic resolution, and control experiments and DFT calculations revealed that 1,3-aryl migration is concerted and intramolecular, proceeding through a four-membered transition state.
Article
Chemistry, Multidisciplinary
Hui-Chun Wu, Chen Wang, Ying-Han Chen, Yan-Kai Liu
Summary: An organocatalytic vinylogous Michael addition triggered triple-cascade reaction has been developed, resulting in the formation of benzofused oxabicyclo[3.3.1]nonanes with one quaternary stereocenter with excellent stereoselectivities.
CHEMICAL COMMUNICATIONS
(2021)
Article
Chemistry, Organic
Chaitanya Ittamalla, Saikrishna Chintha, Nagaraju Medishetti, Jagadeesh Babu Nanubolu, Krishnaiah Atmakur
Summary: The title compounds were synthesized through a reaction between vinyl malononitriles and arylidene pyrazolones catalyzed by base. The reaction involves Michael addition followed by intramolecular cyclization, resulting in the formation of two new C-C bonds. Furthermore, the same reaction with alpha,alpha-dicyano olefins and vinyl malononitriles produces 1,6-dihydro biphenyl compounds. The advantages of this protocol include simple reaction conditions, high yields, and compatibility.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Arijit Hazra, Asit Ghosh, Neeraj Yadav, Prabal Banerjee
Summary: The first asymmetric (3+3)-cycloaddition of ortho-substituted phenyl nitrones with aryl cyclopropane carbaldehydes has been achieved using secondary amine catalysts. While other ortho-substituents gave 1,2-oxazinanes, ortho-hydroxy compounds provided a novel class of tetrahydrochromeno-1,2-oxazine cores through rare 1,3-aryl migration followed by cyclization. An unusual type of asymmetric approach was also discovered.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Arijit Hazra, Asit Ghosh, Neeraj Yadav, Prabal Banerjee
Summary: The first asymmetric (3+3)-cycloaddition of ortho-substituted phenyl nitrones with aryl cyclopropane carbaldehydes has been successfully demonstrated using secondary amine catalysts. While other ortho-substituents led to 1,2-oxazinanes, ortho-hydroxy groups provided a novel class of tetrahydrochromeno-1,2-oxazine cores via rare 1,3-aryl migration followed by cyclization. An unusual type of asymmetric approach was also recognized.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Mateusz Dyguda, Anna Skrzynska, Leslaw Sieron, Lukasz Albrecht
Summary: This manuscript describes the first enantioselective dearomative Michael addition between alpha,beta-unsaturated aldehydes and 2-nitrobenzofurans realized under N-heterocyclic carbene activation. The reaction can efficiently form biologically important heterocycles with high yields and stereoselectivities.
CHEMICAL COMMUNICATIONS
(2022)
Article
Chemistry, Organic
Yan Li, Mingchao Zhang, Zhiqiang Zhang
Summary: A systematic computational study was performed to disclose the reaction mechanism and selectivity in the NHC-catalyzed reaction of 2-bromoenal and 6-methyluracil-5-carbaldehyde. The catalytic cycle was found to consist of eight elementary steps, with the Bronsted acid playing a crucial role in proton transfer and decarboxylation. Addition to 6-methyluracil-5-carbaldehyde was identified as the determining factor for chemo- and stereoselectivity, with CH...N, CH...p, and LP...p interactions influencing the stereoselectivity.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Zhibing Weng, Ying Zhou, Xin Yue, Feng Jiang, Wengang Guo
Summary: In this study, catalytic asymmetric alpha-regioselective Michael additions of vinylogous alpha-ketoester enolates were conducted efficiently using a chiral bifunctional organocatalyst. The reactions yielded Rauhut-Currier type products with high yields and excellent regio- and enantioselectivities.
Article
Chemistry, Multidisciplinary
Lakshminarayana Satham, Chenikkayala Siva Sankara, Shweta Bhagat, Irishi N. N. Namboothiri
Summary: A [3+2] annulation reaction between nitroalkylideneoxindoles and isatilydene-malononitriles, triggered by a vinylogous Michael addition, affords 1,2-dispiro-bisoxindoles with three contiguous stereocenters. This regioselective cascade reaction proceeds in good to excellent yields and with complete stereoselectivity. The experimental results are corroborated by DFT calculations, including transition state energy calculations, using the B3LYP/6-31+g(d,p) basis set.
JOURNAL OF CHEMICAL SCIENCES
(2023)
Review
Chemistry, Multidisciplinary
Tommaso Bortolato, Sara Cuadros, Gianluca Simionato, Luca Dell'Amico
Summary: Photoredox catalysis has achieved significant progress in synthetic organic chemistry, with the use of organic catalysts replacing metal catalysts. Organic catalysts have the advantages of lower cost, less toxicity, and the ability for rational modification as needed.
CHEMICAL COMMUNICATIONS
(2022)
Article
Chemistry, Organic
Tommaso Bortolato, Mateusz Dyguda, Alberto Vega-Penaloza, Luca Dell'Amico
Summary: A group of new organic photocatalysts with fine-tailored redox potentials have been synthesized through a straightforward two-step synthesis. These photocatalysts have shown potential in synthetically relevant reactions, outperforming a well-established organic dye in terms of yield.
SYNTHESIS-STUTTGART
(2022)
Article
Chemistry, Organic
Sara Cuadros, Cristian Rosso, Giorgia Barison, Paolo Costa, Marina Kurbasic, Marcella Bonchio, Maurizio Prato, Giacomo Filippini, Luca Dell'Amico
Summary: A mild light-driven protocol for the direct alkylation of phenols is presented, utilizing the photochemical activity of a halogen-bonded complex. This method allows for rapid reaction under microfluidic conditions, delivering a wide range of ortho-alkylated products with high regioselectivity and yields.
Article
Chemistry, Physical
Cristian Rosso, Sara Cuadros, Giorgia Barison, Paolo Costa, Marina Kurbasic, Marcella Bonchio, Maurizio Prato, Luca Dell'Amico, Giacomo Filippini
Summary: We present an efficient photocatalytic method for the direct iodosulfonylation of terminal olefins using alpha-iodo phenylsulfones. The process utilizes a phenol derivative as the precatalytic system and visible-light irradiation. Mechanistic investigations demonstrate the crucial role of the in situ generated phenolate anion in the catalytic process, achieving high yields of up to 95%.
Review
Chemistry, Multidisciplinary
Pietro Franceschi, Sara Cuadros, Giulio Goti, Luca Dell'Amico
Summary: The synthesis of four-membered heterocycles often requires complex procedures and prefunctionalized reactants. An alternative approach is the photochemical [2+2]-heterocycloaddition, but it is limited by the absorption profile of the carbonyl and the use of high-energy UV-light. This review highlights the progress made in developing visible light-driven [2+2]-heterocycloadditions and discusses the remaining challenges and potential future directions.
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, Applied
Enrico Marcantonio, Franca Zanardi, Claudio Curti, Marco Lombardo
Summary: In this study, the mechanism of the stereoselective (4+2) cycloaddition of N-protected 6-methyluracil-5-carbaldehydes and (E)-beta-nitrostyrenes catalyzed by Takemoto's tertiary amine/thiourea organocatalyst was explored using density functional theory calculations. The study revealed a four-step sequence involving a stereo-defining Michael addition followed by a diastereoselective intramolecular Henry reaction. Additionally, a complex network of hydrogen bonding interactions between the chiral catalyst and the reaction partners was discovered.
ADVANCED SYNTHESIS & CATALYSIS
(2023)
Article
Chemistry, Multidisciplinary
Sara Cuadros, Giulio Goti, Giorgia Barison, Alfredo Raulli, Tommaso Bortolato, Giorgio Pelosi, Paolo Costa, Luca Dell'Amico
Summary: We have developed a general method for synthesizing difluoroalkyl bicycloalkanes (CF2-BCAs) as substitutes for aryl ketones and ethers. This method utilizes a dihydrobenzoacridine photocatalyst to generate R-CF2 radicals, which react with propellanes to form the desired products. The approach is versatile and can be applied to complex bioactive molecules, with good yields achieved in 30 examples (up to 87%). The structural features of the CF2-BCP hybrid bioisostere were studied using single crystal X-ray analysis. Additionally, we successfully synthesized a CF2-BCP analogue of a Leukotriene A(4) hydrolase inhibitor, demonstrating the potential of CF2-BCA hybrid bioisosteres in medicinal chemistry.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Enrico Marcantonio, Debora Guazzetti, Kelly Bugatti, Lucia Battistini, Andrea Sartori, Giorgio Pelosi, Claudio Curti, Franca Zanardi
Summary: Organocatalytic asymmetric transformation of aromatic heterocycles via in situ formation of reactive diene species and subsequent cycloaddition has become a powerful tool. This study reveals the efficient and direct preparation of 6,7-dihydrobenzo[d]imidazoles with optimal enantio- and regioselectivities using previously intractable aromatic imidazole rings as cycloaddends. Post-cycloaddition chemical editing allows the modification of imidazole-based ring systems.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Organic
Pietro Franceschi, Elena Rossin, Giulio Goti, Angelo Scopano, Alberto Vega-Penaloza, Mirco Natali, Deepak Singh, Andrea Sartorel, Luca Dell'Amico
Summary: In this study, we developed a novel photocarboxylation method using an organic photoredox catalyst and different dihydropyridine compounds in combination with an organic base. Through mechanistic investigations, we discovered the key role of a hydrogen bonding complex between the dihydropyridine and the base. This method allowed for the synthesis of carboxylic acids under mild reaction conditions, with good yields and synthetic versatility.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Simone Adorinni, Giulio Goti, Lorenzo Rizzo, Federica Grassi, Slavko Kralj, Fatima Matroodi, Mirco Natali, Rita De Zorzi, Silvia Marchesan, Luca Dell'Amico
Summary: The conjugation of photoactive benzophenone with diphenylalanine resulted in a self-assembling photocatalyst, which was investigated in the E -> Z photoisomerization of stilbene derivatives.
CHEMICAL COMMUNICATIONS
(2023)
