Article
Chemistry, Organic
Azusa Kondoh, Masahiro Terada
Summary: In this review, the challenge of expanding the scope of pronucleophiles in the field of chiral Bronsted base catalysis is addressed. The recent efforts to overcome this challenge and broaden the range of viable enantioselective transformations are summarized, focusing on the development and application of two types of chiral organosuperbase catalyst.
Article
Chemistry, Multidisciplinary
Beatrice Bartolomei, Vasco Corti, Maurizio Prato
Summary: In this study, a microwave synthesis method was used to produce a new type of chiral Carbon Nanodots (CNDs), which showed interesting absorption and emission properties and exhibited enantioselective organocatalytic reactions. The CNDs also displayed redox and light-absorbing properties suitable for driving photochemical processes. The CNDs were used as catalysts to promote cross-dehydrogenative coupling, demonstrating their potential to replace molecular catalysts in multiple reactions.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Review
Chemistry, Multidisciplinary
Lihao Liao, Xiaodan Zhao
Summary: Asymmetric electrophilic reactions provide an ideal method for constructing chiral molecules, but there are many limitations. We have developed a series of chiral catalysts based on indane scaffold, which have been successfully used in various asymmetric electrophilic reactions, expanding the scope of electrophilic reactions.
ACCOUNTS OF CHEMICAL RESEARCH
(2022)
Review
Chemistry, Organic
Ryuichi Nishiyori, Taiki Mori, Ken Okuno, Seiji Shirakawa
Summary: Asymmetric organocatalysis using artificial chiral molecular catalysts is a reliable method to create highly enantioenriched chiral compounds. Chiral amine and phosphine catalysts are extensively employed for asymmetric transformations, while the use of chiral sulfide catalysts is limited. This review summarizes recent achievements in chiral sulfide-catalyzed halocyclizations and introduces asymmetric catalyses with related chiral selenides.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2023)
Review
Chemistry, Multidisciplinary
Shovan Mondal, Frederic Dumur, Didier Gigmes, Mukund P. Sibi, Michele P. Bertrand, Malek Nechab
Summary: Benefiting from the increase in fundamental knowledge, there has been a continuous burst of new ideas and catalytic methods for enantioselective radical reactions in the past 20 years. This review provides a comprehensive survey of the progress achieved during this period, focusing on chiral organocatalysts and transition-metal redox catalysis. The review also discusses the merger of photocatalysis with organo- or metalla-photocatalysis and enzyme-catalyzed reactions involving radical intermediates.
Article
Chemistry, Physical
Minami Odagi, Kazuo Nagasawa
Summary: This paper describes recent progress in chiral hypoiodite-catalyzed enantioselective oxidative bond-forming reactions, focusing on the applications of ammonium and guanidinium salts as onium iodites in carbon-oxygen, carbon-nitrogen, and carbon-carbon bond formation reactions.
Article
Chemistry, Multidisciplinary
Ayla Sirin-Sariaslan, Stefan Naumann
Summary: The stereoselective polymerization of epoxides can be achieved with organocatalysts, resulting in well-defined and high molar mass polyethers. This method also allows the incorporation of stereocontrolled polyether blocks in complex polymer architectures.
Review
Chemistry, Multidisciplinary
Matthew J. Genzink, Jesse B. Kidd, Wesley B. Swords, Tehshik P. Yoon
Summary: Asymmetric photocatalysis is a major research topic in contemporary synthetic organic chemistry. However, the discovery of general strategies for highly enantioselective photochemical reactions has been a recent development, leading to a somewhat limited variety of stereocontrolled photoreactions. This review summarizes the chiral catalyst structures that have been studied for solution-phase asymmetric photochemistry, providing insight into the logic required for highly effective stereocontrolled photocatalysis.
Review
Chemistry, Multidisciplinary
Oleksandr Vyhivskyi, Anton Kudashev, Takeru Miyakoshi, Olivier Baudoin
Summary: Processes involving transition-metal catalysis have become a major part of synthetic chemists' toolbox in recent decades. The focus has shifted from cross-coupling reactions to C-H bond functionalization, with constant progress leading to discovery of enantioselective methods. The review discusses enantioselective Pd-0-catalyzed C-H activation, highlighting the importance of different chiral ligands and catalysts in enabling these transformations.
CHEMISTRY-A EUROPEAN JOURNAL
(2021)
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.
Review
Chemistry, Multidisciplinary
Mo Wang, Zhenfeng Zhang, Wanbin Zhang
Summary: This article introduces the development of chiral bicyclic imidazole catalysts by our research group, including their design, synthesis, and application. By using different skeletons and substituents, a series of highly active and selective catalysts were successfully prepared and applied in asymmetric synthesis reactions. This research provides important insights and guidance for exploring new organocatalysts and related reactions.
ACCOUNTS OF CHEMICAL RESEARCH
(2022)
Review
Chemistry, Multidisciplinary
Puja Saha, Deepanjan Panda, Jyotirmayee Dash
Summary: Nucleic acids are crucial in cellular information transfer and gene regulation. DNA and RNA molecules are associated with human diseases and offer opportunities for small molecule-based therapeutics. However, developing target-selective molecules with defined biological activity has always been challenging.
CHEMICAL SOCIETY REVIEWS
(2023)
Article
Chemistry, Physical
Connor Kabes, Reagan Lucas, Jack Gunn, John Gladysz
Summary: The lipophilic diastereomeric cobalt complexes catalyze enantioselective C-H bond addition reactions with aliphatic tertiary amines. Incorporating different bases into counter anions can lead to highly enantioselective bifunctional catalysts, where salts of nicotinates and related compounds have been found effective. The 6-aminonicotinate salt gives the best results among the tested bases.
Review
Chemistry, Organic
Li Xin, Song Qiuling
Summary: Chiral boranes have emerged as privileged catalysts in asymmetric reactions due to their lower catalyst loading and easier access compared to chiral transition metal catalysts. This article summarizes and discusses the chiral borane-catalyzed enantioselective reactions, organized into three parts based on reaction categories.
CHINESE JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Zi-Qi Yi, Bo-Wen Deng, Fei Chen, Yan-Mei He, Qing-Hua Fan
Summary: Highly efficient asymmetric hydrogenation of dibenzo[b,f][1,4]oxazepine, dibenzo[b,f][1,4]thiazepine and dibenzo[b,e]azepine derivatives was achieved using chiral cationic ruthenium diamine catalysts, affording diverse chiral seven-membered N-heterocycles with excellent results (up to 99% yield and 99% ee). Additionally, it was observed that the enantioselectivity in the hydrogenation of dibenzo[b,f][1,4]thiazepine and dibenzo[b,e]azepine derivatives could be significantly regulated by the catalyst counteranion.
NEW JOURNAL OF CHEMISTRY
(2023)
Article
Chemistry, Organic
Noah Jeremias, Martin T. Peschel, Constantin Jaschke, Regina de Vivie-Riedle, Thorsten Bach
Summary: In this study, it was found that cyclopent-2-enones can undergo a photochemical rearrangement to form ketenes when substituted in the 5,5-position, accompanied by the formation of cyclopropane. By trapping the ketene intermediates with primary amines, efficient synthesis of 2,2-disubstituted cyclopropaneacetic amides was achieved.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Organic
Audrey Gilbert, Thorsten Bach
Summary: Photochemical cascade (domino) reactions can construct complex molecular architectures through consecutive reactions with high diastereoselectivity.
Article
Chemistry, Multidisciplinary
Roger Jan Kutta, Johannes Grosskopf, Nils van Staalduinen, Antonia Seitz, Philipp Pracht, Stefan Breitenlechner, Christoph Bannwarth, Patrick Nuernberger, Thorsten Bach
Summary: In the presence of a chiral benzophenone catalyst, a racemic mixture of a chiral imidazolidine-2,4-dione can be converted into the same compound with high enantiomeric excess through photochemical deracemization. Mechanistic experiments revealed that the catalyst binds the two enantiomers through hydrogen bonding and facilitates hydrogen atom transfer to the photoexcited benzophenone. Quantum chemical calculations showed that the back hydrogen atom transfer occurs to the oxygen atom of the hydantoin radical. The results provide insights into a synthetically useful photochemical deracemization reaction.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Organic
Johannes Hofer, Franziska Pecho, Thorsten Bach
Summary: Under visible light irradiation, cyclic 2-alk-4enyl-substituted 1,3-diketones undergo an intramolecular endo-addition onto the double bond, resulting in spirocyclic products with yields ranging from 62 to 92%. The reaction can be promoted by both an organic photocatalyst (thioxanthone, 20 mol%) and an organometallic Ir-based photocatalyst (5 mol%). The addition of triisopropylthiophenol is necessary to obtain high yields.
Article
Chemistry, Multidisciplinary
Johannes Grosskopf, Alexandra A. Heidecker, Thorsten Bach
Summary: Racemic 3-substituted oxindoles can be converted into enantiomerically pure or enriched material through photochemical deracemization process. Light energy compensates for the loss of entropy and enables predictable editing of the stereogenic center. The obtained oxindoles are valuable intermediates for further transformations with complete retention at the stereogenic center.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Editorial Material
Chemistry, Organic
Anat Milo, Takashi Ooi, Thorsten Bach
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Organic
Niklas Rauscher, Christian Jandl, Thorsten Bach
Summary: A recent photochemical cascade reaction has been developed to access diastereomeric pentacyclic products that possess the carbon skeleton of prezizane natural products. The minor diastereoisomer, with a 2 beta-Me configuration, was transformed into (+)-prezizaan-15-ol through 12 reaction steps. Similarly, the major diastereoisomer, with a 2 alpha-Me configuration, yielded (+)-jinkohol II in an analogous route and was further oxidized at C13 to yield (+)-jinkoholic acid. Total synthesis of these natural products helped clarify their configurations.
Article
Chemistry, Organic
Johanna Proessdorf, Christian Jandl, Thomas Pickl, Thorsten Bach
Summary: Naturally occurring sesquiterpenes with a protoilludane skeleton are frequently oxygenated at carbon atoms C4 and C8. Boronic acid pinacol esters (BPin) can serve as precursors for hydroxy groups at these positions and synthetic methods have been developed for their preparation. Introduction of a boronate at position C4 was achieved through Cu-catalyzed hydroboration of a photochemically generated cyclobutene precursor, while introduction of BPin at carbon atom C8 was accomplished through a photochemical transformation starting with an alkenyl boronate. Subsequent reactions showed the oxidative transformation of boronates into the respective alcohols.
SYNTHESIS-STUTTGART
(2023)
Article
Chemistry, Physical
Malte Leverenz, Hendrik Brockmann, Andreas Dreuw, Thorsten Bach, Golo Storch
Summary: A strong enantiodivergence was observed in the oxadi-x-methane rearrangement of 2,4cyclohexadienones, ranging from +92% ee to -45% ee. The stereochemical outcome is determined solely by the oxazaborolidine substituents. The change in enantioselectivity is linked to a change in substrate binding, and TDDFT studies in the S1 excited state provided further mechanistic insights.
Article
Chemistry, Multidisciplinary
Johannes Grosskopf, Manuel Plaza, Roger Jan Kutta, Patrick Nuernberger, Thorsten Bach
Summary: 2,5-Diketopiperazines are cyclic dipeptides with a wide range of applications, and their enantioselective preparation can be achieved through photochemical deracemization, allowing for stereochemical editing at a single position while maintaining other stereogenic centers unaffected. The chiral benzophenone catalyst in combination with irradiation at lambda=366 nm enables the establishment of configuration at the stereogenic carbon atom C6 at will.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Lilla Koser, Thorsten Bach
Summary: The first total synthesis of (-)-5-deoxyenterocin has been accomplished, starting from pentane-1,3,5-triol with a linear sequence of 16 steps and an overall yield of 0.2%. Key steps of the synthesis include aldol reactions, hydroxylation reactions, and an intramolecular aldol reaction. Despite attempts, a functionalization reaction at position C5 was unsuccessful.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Organic
Daniel P. Schwinger, Thomas Pickl, Thorsten Bach
Summary: Cyclohept-1-ene-1-carbaldehyde undergoes photoinduced E & RARR; Z isomerization at & lambda; =350 nm. The ring strain facilitates various reactions, including Diels-Alder cycloadditions, [3 + 2] cycloadditions, and enereactions. The products obtained are trans-fusedat the cycloheptane core and yield up to 82%. Single crystal X-ray analyses confirm the structure and relative configuration. In the presence of BF3 and 2,3-dimethylbuta-1,3-diene, cyclohept-1-ene-1-carbaldehyde undergoes a stereoselective rearrangement to form a tricyclic ketone (87%).
JOURNAL OF ORGANIC CHEMISTRY
(2023)
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)
Review
Chemistry, Multidisciplinary
Johannes Grosskopf, Thorsten Bach
Summary: Upon irradiation with a suitable chiral catalyst, racemic compounds can be converted into enantiopure compounds through a process called photochemical deracemization. This review comprehensively covers the research and current developments in this field, discussing the reactions and mechanistic details underlying the presented reaction. Photochemical deracemization offers a unique opportunity to directly obtain enantiopure compounds from racemates, and short-lived intermediates play a key role in determining the enantioselectivity.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Organic
Freya M. M. Harvey, Alexandra H. H. Heidecker, Christian Merten, Thorsten Bach
Summary: Allenes with different substituents at their terminal carbon atom exhibit axial chirality and can be obtained in enantiopure form through a photochemical deracemization protocol. This study investigates the conditions under which allenoic acid derivatives undergo a Diels-Alder reaction with 1,3-cyclopentadienes and the resulting products. Cyclic derivatives (lactams, lactones) exhibited an exo-selective reaction catalyzed by the Lewis acid Eu(fod)(3), while acyclic derivatives mainly produced endo-products (with EtAlCl2 as the preferred Lewis acid). The exocyclic double bond exhibited excellent diastereoselectivity and achieved near-perfect chirality transfer. The method was successfully applied to the synthesis of sesquiterpenes beta-santalol (1) and 10(E)-beta-santalic acid (13).
ORGANIC & BIOMOLECULAR CHEMISTRY
(2023)