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Wei B, Chen YH, Knochel P. Recent Advances in Halogen-Metal Exchange Reactions. Acc Chem Res 2024. [PMID: 38953535 DOI: 10.1021/acs.accounts.4c00242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2024]
Abstract
ConspectusThe halogen-metal exchange reaction is a very powerful method for preparing functionalized organometallic reagents in the fields of organic and organometallic chemistry. Since its inception, significant interest has been directed toward the on-demand development of new halogen-metal exchange reactions, primarily through the upgrading of exchange reagents. The enduring quest for optimal reactivity, superior functional group compatibility, and innovative synthetic applications of exchange reagents remains a fundamental objective. In the past several years, the emergence of some significant discoveries in halogen-metal exchange reactions has proclaimed a renaissance to this field. This Account outlines the latest advances within the domain contributed by the Knochel group, including the main points as follows.The stereoretentive I/Li exchange on stereodefined secondary alkyl iodides was developed for the synthesis of nonstabilized chiral secondary alkyllithium reagents. This provided a straightforward method to access chiral organolithium reagents, which can be trapped by various electrophiles or transmetalated with other metals such as copper, zinc, and magnesium, thus enabling the stereoselective synthesis of a series of functionalized compounds and natural products.Faster halogen-magnesium and halogen-zinc exchanges in toluene were realized using a novel kind of exchange reagent complexed with lithium alkoxide. These highly efficient exchange reactions are much faster than traditional ones and performed in an industrially friendly solvent. These advantages are of great value in practical synthesis, paving the way for new developments in this evolving area.Halogen-lanthanide exchanges and their novel applications in organic synthesis were established. These new exchanges introduced the lanthanide metals into halogen-metal exchange reactions for the first time, thereby opening new avenues in synthetic chemistry. Building on these achievements, a comparative analysis of the exchange reaction rates by kinetic study has quantified the relationship between the electronegativity of metals and the rates of halogen-metal exchanges.Br/Na exchange in continuous flow was achieved using a hexane-soluble exchange reagent, 2-ethylhexylsodium. This approach effectively circumvented the poor solubility of the organosodium reagent, which has proven to be of significant practical value and greatly enhanced the synthetic utility of the organosodium reagent in organic synthesis.These remarkable breakthroughs as mentioned above are fueled mainly by upgrading the exchange reagents, resulting in the development of new halogen-metal exchange reactions and innovative applications in organic synthesis. Given the importance of halogen-metal exchanges in synthetic chemistry, the pursuit of other types of exchange reactions, particularly those involving new metals, will be in continuous demand. This Account provides a timely summary of recent progress and will undoubtedly inspire further advances to drive this research field forward.
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Affiliation(s)
- Baosheng Wei
- College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, Hunan China
| | - Yi-Hung Chen
- Institute for Advanced Studies (IAS), College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, Hubei China
| | - Paul Knochel
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, Haus F, 81377 München, Germany
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Anderson DE, Truong AHN, Hevia E. Dual Basicity and Nucleophilicity of Organosodium Reagents in Benzylic C-H Additions of Toluenes to Diarylethenes and Ketones. Chemistry 2024:e202400492. [PMID: 38651778 DOI: 10.1002/chem.202400492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Revised: 04/22/2024] [Accepted: 04/23/2024] [Indexed: 04/25/2024]
Abstract
Profiting from the dual high basicity and nucleophilicity of organosodium complexes, here we report the stepwise lateral metalation of a wide range of alkyl arenes (MeAr), mediated by hydrocarbon-soluble NaCH2SiMe3 ⋅ PMDETA (PMDETA=N,N,N',N'',N''-pentamethyldiethylenetriamine), followed by nucleophilic addition to diarylethenes of the newly generated NaCH2Ar ⋅ PMDETA complexes. This method grants access to a range of functionalised hydrocarbons in excellent yields and can be upgraded to catalytic regimes when using trans-stilbene, a 10 mol% of the alkyl sodium base and toluene as a solvent. Extending this approach to aromatic ketones leads to the formation of stilbenes under mild reaction conditions, resulting from the deprotonative coupling of toluenes with ketones. Combining spectroscopic studies with the trapping and characterisation of key reaction intermediates, mechanistic insights have been gained, advancing the understanding of coordination effects in organosodium chemistry, and shedding light on their special reactivity profiles.
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Affiliation(s)
- David E Anderson
- Departement für Chemie, Biochemie und Pharmazie, Universität Bern, Freiestrasse 3, 3012, Bern, Switzerland
| | - Alex H N Truong
- Departement für Chemie, Biochemie und Pharmazie, Universität Bern, Freiestrasse 3, 3012, Bern, Switzerland
| | - Eva Hevia
- Departement für Chemie, Biochemie und Pharmazie, Universität Bern, Freiestrasse 3, 3012, Bern, Switzerland
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Anderson DE, Tortajada A, Hevia E. New Frontiers in Organosodium Chemistry as Sustainable Alternatives to Organolithium Reagents. Angew Chem Int Ed Engl 2024; 63:e202313556. [PMID: 37801443 DOI: 10.1002/anie.202313556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 10/05/2023] [Accepted: 10/06/2023] [Indexed: 10/08/2023]
Abstract
With their highly reactive respective C-Na and N-Na bonds, organosodium and sodium amide reagents could be viewed as obvious replacements or even superior reagents to the popular, widely utilised organolithiums. However, they have seen very limited applications in synthesis due mainly to poor solubility in common solvents and their limited stability. That notwithstanding in recent years there has been a surge of interest in bringing these sustainable metal reagents into the forefront of organometallics in synthesis. Showcasing the growth in utilisation of organosodium complexes within several areas of synthetic chemistry, this Minireview discusses promising new methods that have been recently reported with the goal of taming these powerful reagents. Special emphasis is placed on coordination and aggregation effects in these reagents which can impart profound changes in their solubility and reactivity. Differences in observed reactivity between more nucleophilic aryl and alkyl sodium reagents and the less nucleophilic but highly basic sodium amides are discussed along with current mechanistic understanding of their reactivities. Overall, this review aims to inspire growth in this exciting field of research to allow for the integration of organosodium complexes within common important synthetic transformations.
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Affiliation(s)
- David E Anderson
- Department für Chemie und Biochemie, Universität Bern, Freiestrasse 3, 3012, Bern, Switzerland
| | - Andreu Tortajada
- Department für Chemie und Biochemie, Universität Bern, Freiestrasse 3, 3012, Bern, Switzerland
| | - Eva Hevia
- Department für Chemie und Biochemie, Universität Bern, Freiestrasse 3, 3012, Bern, Switzerland
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Masuda R, Yasukawa T, Yamashita Y, Maki T, Yoshida T, Kobayashi S. Heterogeneous Single-Atom Zinc on Nitrogen-Doped Carbon Catalyzed Electrochemical Allylation of Imines. J Am Chem Soc 2023. [PMID: 37224473 DOI: 10.1021/jacs.3c03674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Organometallic reagents are effective for carbon-carbon bond formation; however, consumption of stoichiometric amounts of metals is problematic. We developed electrochemical allylation reactions of imines catalyzed by nitrogen-doped carbon-supported single-atom zinc, which were fixed on a cathode to afford a range of homoallylic amines efficiently. The system could suppress generation of metallic waste, and the catalyst electrode showed advantages over bulk zinc in terms of activity and robustness. An electrochemical flow reaction was also successfully performed to produce the homoallylic amine continuously with minimum amounts of waste.
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Affiliation(s)
- Ryusuke Masuda
- Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Tomohiro Yasukawa
- Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Yasuhiro Yamashita
- Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Tei Maki
- Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Tomoko Yoshida
- Research Center for Artificial Photosynthesis, Osaka Metropolitan University, Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan
| | - Shu Kobayashi
- Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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5
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Anderson DE, Tortajada A, Hevia E. Highly Reactive Hydrocarbon Soluble Alkylsodium Reagents for Benzylic Aroylation of Toluenes using Weinreb Amides. Angew Chem Int Ed Engl 2023; 62:e202218498. [PMID: 36636916 DOI: 10.1002/anie.202218498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 01/11/2023] [Accepted: 01/12/2023] [Indexed: 01/14/2023]
Abstract
Deaggregating the alkyl sodium NaCH2 SiMe3 with polydentate nitrogen ligands enables the preparation and characterisation of new, hydrocarbon soluble chelated alkylsodium reagents. Equipped with significantly enhanced metalating power over their organolithium counterparts, these systems can promote controlled sodiation of weakly acidic benzylic C-H bonds from a series of toluene derivatives under mild stoichiometric conditions. This has been demonstrated through the benzylic aroylation of toluenes with Weinreb amides, that delivers a wide range of 2-arylacetophenones in good to excellent yields. Success in isolating and determining the structures of key organometallic intermediates has provided useful mechanistic insight into these new sodium-mediated transformations.
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Affiliation(s)
- David E Anderson
- Department für Chemie, Biochemie und Pharmazie, Universität Bern, Freiestrasse 3, 3012, Bern, Switzerland
| | - Andreu Tortajada
- Department für Chemie, Biochemie und Pharmazie, Universität Bern, Freiestrasse 3, 3012, Bern, Switzerland
| | - Eva Hevia
- Department für Chemie, Biochemie und Pharmazie, Universität Bern, Freiestrasse 3, 3012, Bern, Switzerland
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Kremsmair A, Wilke HR, Harenberg JH, Bissinger BRG, Simon MM, Alandini N, Knochel P. In Situ Quench Reactions of Enantioenriched Secondary Alkyllithium Reagents in Batch and Continuous Flow Using an I/Li-Exchange. Angew Chem Int Ed Engl 2023; 62:e202214377. [PMID: 36269064 PMCID: PMC10100098 DOI: 10.1002/anie.202214377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Indexed: 12/05/2022]
Abstract
We report a practical in situ quench (ISQ) procedure involving the generation of chiral secondary alkyllithiums from secondary alkyl iodides (including functionalized iodides bearing an ester or a nitrile) in the presence of various electrophiles such as aldehydes, ketones, Weinreb amides, isocyanates, sulfides, or boronates. This ISQ-reaction allowed the preparation of a broad range of optically enriched ketones, alcohols, amides, sulfides and boronic acid esters in typically 90-98 % ee. Remarkably, these reactions were performed at -78 °C or -40 °C in batch. A continuous flow set-up permitted reaction temperatures between -20 °C and 0 °C and allowed a scale-up up to a 40-fold without further optimization.
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Affiliation(s)
- Alexander Kremsmair
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, Haus F, 81377, München, Germany
| | - Henrik R Wilke
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, Haus F, 81377, München, Germany
| | - Johannes H Harenberg
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, Haus F, 81377, München, Germany
| | - Benjamin R G Bissinger
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, Haus F, 81377, München, Germany
| | - Matthias M Simon
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, Haus F, 81377, München, Germany
| | - Nurtalya Alandini
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, Haus F, 81377, München, Germany
| | - Paul Knochel
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, Haus F, 81377, München, Germany
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7
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Jiang Y, Yorimitsu H. Taming Highly Unstable Radical Anions and 1,4-Organodilithiums by Flow Microreactors: Controlled Reductive Dimerization of Styrenes. JACS AU 2022; 2:2514-2521. [PMID: 36465543 PMCID: PMC9709950 DOI: 10.1021/jacsau.2c00375] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 10/05/2022] [Accepted: 10/05/2022] [Indexed: 05/21/2023]
Abstract
The reduction of styrenes with lithium arenide in a flow microreactor leads to the instantaneous generation of highly unstable radical anions that subsequently dimerize to yield the corresponding 1,4-organodilithiums. A flow reactor with fast mixing is essential for this reductive dimerization as the efficiency and selectivity are low under batch conditions. A series of styrenes undergo dimerization, and the resulting 1,4-organodilithiums are trapped with various electrophiles. Trapping with divalent electrophiles affords precursors for useful yet less accessible cyclic structures, for example, siloles from dichlorosilanes. Thus, we highlight the power of single-electron reduction of unsaturated compounds in flow microreactors for organic synthesis.
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Ma Y, Lui NM, Keresztes I, Woltornist RA, Collum DB. Sodium Isopropyl(trimethylsilyl)amide: A Stable and Highly Soluble Lithium Diisopropylamide Mimic. J Org Chem 2022; 87:14223-14229. [PMID: 36282953 PMCID: PMC10042304 DOI: 10.1021/acs.joc.2c01745] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The preparation, structure, physical properties, and reactivities of sodium isopropyl(trimethylsilyl)amide (NaPTA) are described. The solubilities at room temperature range from n-heptane (0.55 M), n-hexane (0.60 M), toluene (0.65 M), MTBE (1.7 M), Et3N (3.2 M), and THF (>6.0 M). The half-life to destruction in neat THF is >1 year at 25 °C and 7 days at 70 °C, which compares favorably to 2.5 months and 1.5 days, respectively, for LDA in neat THF. This study focuses on NaPTA in THF. 29Si NMR spectroscopy shows exclusively a mixture of cis and trans stereoisomeric dimers in 0.10-12 M THF in hexane. Density functional theory (DFT) computations suggest that the pKb is intermediate between dimeric sodium diisopropylamide (NaDA) and dimeric sodium hexamethyldisilazide (NaHMDS). Metalations of arenes, epoxides, ketones, hydrazones, alkenes, and alkyl halides show higher reactivities than LDA (kNaPTA/LDA = 1-30). While the rates of arene metalation are high, the lower pKb of NaPTA limits the substrates. Metalation of pseudoephedrate-based carboxamides to form disodiated Myers enolates solves several challenging technical problems.
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Affiliation(s)
- Yun Ma
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States
| | - Nathan M Lui
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States
| | - Ivan Keresztes
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States
| | - Ryan A Woltornist
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States
| | - David B Collum
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States
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9
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Harenberg JH, Reddy Annapureddy R, Karaghiosoff K, Knochel P. Continuous Flow Preparation of Benzylic Sodium Organometallics. Angew Chem Int Ed Engl 2022; 61:e202203807. [PMID: 35416397 PMCID: PMC9400861 DOI: 10.1002/anie.202203807] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Indexed: 12/14/2022]
Abstract
We report a lateral sodiation of alkyl(hetero)arenes using on‐demand generated hexane‐soluble (2‐ethylhexyl)sodium (1) in the presence of TMEDA. (2‐Ethylhexyl)sodium (1) is prepared via a sodium packed‐bed reactor and used for metalations at ambient temperature in batch as well as in continuous flow. The resulting benzylic sodium species are subsequently trapped with various electrophiles including carbonyl compounds, epoxides, oxetane, allyl/benzyl chlorides, alkyl halides and alkyl tosylates. Wurtz‐type couplings with secondary alkyl halides and tosylates proceed under complete inversion of stereochemistry. Furthermore, the utility of this lateral sodiation is demonstrated in the synthesis of pharmaceutical relevant compounds. Thus, fingolimod is prepared from p‐xylene applying the lateral sodiation twice. In addition, 7‐fold isotopically labeled salmeterol‐d7 and fenpiprane as well as precursors to super linear alkylbenzene (SLAB) surfactants are prepared.
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Affiliation(s)
- Johannes H. Harenberg
- Department ChemieLudwig-Maximilians-Universität MünchenButenandtstraße 5–13, Haus F81377MünchenGermany
| | | | - Konstantin Karaghiosoff
- Department ChemieLudwig-Maximilians-Universität MünchenButenandtstraße 5–13, Haus F81377MünchenGermany
| | - Paul Knochel
- Department ChemieLudwig-Maximilians-Universität MünchenButenandtstraße 5–13, Haus F81377MünchenGermany
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10
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Kleoff M, Kiler P, Heretsch P. Synthesis of odorants in flow and their applications in perfumery. Beilstein J Org Chem 2022; 18:754-768. [PMID: 35859624 PMCID: PMC9263551 DOI: 10.3762/bjoc.18.76] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 06/09/2022] [Indexed: 11/24/2022] Open
Abstract
Continuous flow technology is a key technology for sustainable manufacturing with numerous applications for the synthesis of fine chemicals. In recent years, the preparation of odorants utilizing the advantages of flow reactors received growing attention. In this review, we give an overview of selected methods for the synthesis of odorants in flow, including heterogeneously catalyzed reactions, gas reactions, and photochemical C–H functionalization processes. After a brief introduction on types of odorants, the presented odorant syntheses are ordered according to the main odor families “fruity”, “green”, “marine”, “floral”, “spicy”, “woody”, “ambery”, and “musky” and their use and importance for perfumery is briefly discussed.
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Affiliation(s)
- Merlin Kleoff
- Freie Universität Berlin, Institut für Chemie und Biochemie, Fabeckstr. 34-36, 14195 Berlin, Germany
| | - Paul Kiler
- PK Perfumes, Menifee, California, United States of America
| | - Philipp Heretsch
- Leibniz Universität Hannover, Institut für Organische Chemie, Schneiderberg 1B, 30167 Hannover, Germany
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11
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Bole LJ, Tortajada A, Hevia E. Enhancing Metalating Efficiency of the Sodium Amide NaTMP in Arene Borylation Applications. Angew Chem Int Ed Engl 2022; 61:e202204262. [PMID: 35420221 PMCID: PMC9323492 DOI: 10.1002/anie.202204262] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Indexed: 12/12/2022]
Affiliation(s)
- Leonie J. Bole
- Departement für Chemie, Biochemie und Pharmazie Universität Bern Freiestrasse 3 3012 Bern Switzerland
| | - Andreu Tortajada
- Departement für Chemie, Biochemie und Pharmazie Universität Bern Freiestrasse 3 3012 Bern Switzerland
| | - Eva Hevia
- Departement für Chemie, Biochemie und Pharmazie Universität Bern Freiestrasse 3 3012 Bern Switzerland
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12
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Tortajada A, Anderson DE, Hevia E. Gram‐Scale Synthesis, Isolation and Characterisation of Sodium Organometallics: nBuNa and NaTMP. Helv Chim Acta 2022. [DOI: 10.1002/hlca.202200060] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Andreu Tortajada
- Universitat Bern Department of Chemistry, Biochemistry and Pharmaceutical Sciences SWITZERLAND
| | - David E Anderson
- Universitat Bern Department of Chemistry, Biochemistry and Pharmaceutical Sciences SWITZERLAND
| | - Eva Hevia
- Universitat Bern Department of Chemistry and Biochemistry Freiestrasse 3 3012 Bern SWITZERLAND
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13
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Bole L, Tortajada A, Hevia E. Enhancing Metalating Efficiency of the Sodium Amide NaTMP in Arene Borylation Applications. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202204262] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Leonie Bole
- Universitat Bern Department of Chemistry, Biochemistry and Pharmaceutical Sciences SWITZERLAND
| | - Andreu Tortajada
- Universitat Bern Department of Chemistry, Biochemistry and Pharmaceutical Sciences SWITZERLAND
| | - Eva Hevia
- Universitat Bern Department of Chemistry and Biochemistry Freiestrasse 3 3012 Bern SWITZERLAND
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14
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Harenberg JH, Annapureddy RR, Karaghiosoff K, Knochel P. Continuous Flow Preparation of Benzylic Sodium Organometallics. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202203807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | | | | | - Paul Knochel
- Ludwig-Maximilians-Universitat Munchen Department of Chemistry Butenandtstr. 5-13 81377 München GERMANY
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15
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Asako S, Takahashi I, Kurogi T, Murakami Y, Ilies L, Takai K. Birch Reduction of Arenes Using Sodium Dispersion and DMI under Mild Conditions. CHEM LETT 2022. [DOI: 10.1246/cl.210546] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Sobi Asako
- Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530, Japan
- RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Ikko Takahashi
- RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Takashi Kurogi
- Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530, Japan
| | - Yoshiaki Murakami
- KOBELCO ECO-Solutions Co., Ltd., 4-78-1 Wakinohama-cho, Chuo-ku, Kobe 651-0072, Japan
| | - Laurean Ilies
- RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Kazuhiko Takai
- Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530, Japan
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16
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Woltornist RA, Collum DB. Ketone Enolization with Sodium Hexamethyldisilazide: Solvent- and Substrate-Dependent E- Z Selectivity and Affiliated Mechanisms. J Am Chem Soc 2021; 143:17452-17464. [PMID: 34643382 PMCID: PMC10042305 DOI: 10.1021/jacs.1c06529] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Ketone enolization by sodium hexamethyldisilazide (NaHMDS) shows a marked solvent and substrate dependence. Enolization of 2-methyl-3-pentanone reveals E-Z selectivities in Et3N/toluene (20:1), methyl-t-butyl ether (MTBE, 10:1), N,N,N',N″,N″-pentamethyldiethylenetriamine (PMDTA)/toluene (8:1), TMEDA/toluene (4:1), diglyme (1:1), DME (1:22), and tetrahydrofuran (THF) (1:90). Control experiments show slow or nonexistent stereochemical equilibration in all solvents except THF. Enolate trapping with Me3SiCl/Et3N requires warming to -40 °C whereas Me3SiOTf reacts within seconds. In situ enolate trapping at -78 °C using preformed NaHMDS/Me3SiCl mixtures is effective in Et3N/toluene yet fails in THF by forming (Me3Si)3N. Rate studies show enolization via mono- and disolvated dimers in Et3N/toluene, disolvated dimers in TMEDA, trisolvated monomers in THF/toluene, and free ions with PMDTA. Density functional theory computations explore the selectivities via the E- and Z-based transition structures. Failures of theory-experiment correlations of ionic fragments were considerable even when isodesmic comparisons could have canceled electron correlation errors. Swapping 2-methyl-3-pentanone with a close isostere, 2-methylcyclohexanone, causes a fundamental change in the mechanism to a trisolvated-monomer-based enolization in THF.
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Affiliation(s)
- Ryan A Woltornist
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States
| | - David B Collum
- Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States
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17
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Bonner A, Loftus A, Padgham AC, Baumann M. Forgotten and forbidden chemical reactions revitalised through continuous flow technology. Org Biomol Chem 2021; 19:7737-7753. [PMID: 34549240 DOI: 10.1039/d1ob01452h] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Continuous flow technology has played an undeniable role in enabling modern chemical synthesis, whereby a myriad of reactions can now be performed with greater efficiency, safety and control. As flow chemistry furthermore delivers more sustainable and readily scalable routes to important target structures a growing number of industrial applications are being reported. In this review we highlight the impact of flow chemistry on revitalising important chemical reactions that were either forgotten soon after their initial report as necessary improvements were not realised due to a lack of available technology, or forbidden due to unacceptable safety concerns relating to the experimental procedure. In both cases flow processing in combination with further reaction optimisation has rendered a powerful set of tools that make such transformations not only highly efficient but moreover very desirable due to a more streamlined construction of desired scaffolds. This short review highlights important contributions from academic and industrial laboratories predominantly from the last 5 years allowing the reader to gain an appreciation of the impact of flow chemistry.
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Affiliation(s)
- Arlene Bonner
- School of Chemistry, University College Dublin, Science Centre South, D04 N2E5, Dublin, Ireland.
| | - Aisling Loftus
- School of Chemistry, University College Dublin, Science Centre South, D04 N2E5, Dublin, Ireland.
| | - Alex C Padgham
- School of Chemistry, University College Dublin, Science Centre South, D04 N2E5, Dublin, Ireland.
| | - Marcus Baumann
- School of Chemistry, University College Dublin, Science Centre South, D04 N2E5, Dublin, Ireland.
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18
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Ma Y, Woltornist RA, Algera RF, Collum DB. Reactions of Sodium Diisopropylamide: Liquid-Phase and Solid-Liquid Phase-Transfer Catalysis by N, N, N', N″, N″-Pentamethyldiethylenetriamine. J Am Chem Soc 2021; 143:13370-13381. [PMID: 34375095 PMCID: PMC10042303 DOI: 10.1021/jacs.1c06528] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Sodium diisopropylamide (NaDA) in N,N-dimethylethylamine (DMEA) and DMEA-hydrocarbon mixtures with added N,N,N',N″,N″-pentamethyldiethylenetriamine (PMDTA) reacts with alkyl halides, epoxides, hydrazones, arenes, alkenes, and allyl ethers. Comparisons of PMDTA with N,N,N',N'-tetramethylethylenediamine (TMEDA) accompanied by detailed rate and computational studies reveal the importance of the trifunctionality and κ2-κ3 hemilability. Rate studies show exclusively monomer-based reactions of 2-bromooctane, cyclooctene oxide, and dimethylresorcinol. Catalysis with 10 mol % PMDTA shows up to >30-fold accelerations (kcat > 300) with no evidence of inhibition over 10 turnovers. Solid-liquid phase-transfer catalysis (SLPTC) is explored as a means to optimize the catalysis as well as explore the merits of heterogeneous reaction conditions.
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Affiliation(s)
- Yun Ma
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | - Ryan A. Woltornist
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | - Russell F. Algera
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
| | - David B. Collum
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853–1301
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19
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Knochel P, Djukanovic D, Heinz B, Mandrelli F, Mostarda S, Filipponi P, Martin B. Continuous Flow Acylation of (Hetero)aryllithiums with Polyfunctional N,N-Dimethylamides and Tetramethylurea in Toluene. Chemistry 2021; 27:13977-13981. [PMID: 34387898 PMCID: PMC8519161 DOI: 10.1002/chem.202102805] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Indexed: 11/05/2022]
Abstract
The continuous flow reaction of various aryl or heteroaryl bromides in toluene in the presence of THF (1.0 equiv) with sec -BuLi (1.1 equiv) provided at 25 °C within 40 sec the corresponding aryllithiums which were acylated with various functionalized N,N-dimethylamides including easily enolizable amides at -20 °C within 27 sec, producing highly functionalized ketones in 48-90% yield (36 examples). This method was well suited for the preparation of α-chiral ketones such as naproxene and ibuprofen derived ketones with 99% ee . A one-pot stepwise bis-addition of two different lithium organometallics to 1,1,3,3-tetramethyurea (TMU) provided unsymmetrical ketones in 69-79% yield (9 examples).
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Affiliation(s)
- Paul Knochel
- Ludwig-Maximilians-Universitat Munchen, Department of Chemistry, Butenandtstr. 5-13, 81377, München, GERMANY
| | - Dimitrije Djukanovic
- Ludwig Maximillians University Munich: Ludwig-Maximilians-Universitat Munchen, Chemistry, GERMANY
| | - Benjamin Heinz
- Ludwig Maximillians University Munich: Ludwig-Maximilians-Universitat Munchen, Chemistry, GERMANY
| | | | - Serena Mostarda
- Novartis Pharma Schweiz AG, Chemical Development, SWITZERLAND
| | - Paolo Filipponi
- Novartis Pharma Schweiz AG, Chemical Development, SWITZERLAND
| | - Benjamin Martin
- Novartis Pharma Schweiz AG, Chemical Development, SWITZERLAND
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20
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Harenberg JH, Weidmann N, Wiegand AJ, Hoefer CA, Annapureddy RR, Knochel P. (2-Ethylhexyl)sodium: A Hexane-Soluble Reagent for Br/Na-Exchanges and Directed Metalations in Continuous Flow. Angew Chem Int Ed Engl 2021; 60:14296-14301. [PMID: 33826212 PMCID: PMC8252725 DOI: 10.1002/anie.202103031] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Indexed: 12/14/2022]
Abstract
We report the on-demand generation of hexane-soluble (2-ethylhexyl)sodium (1) from 3-(chloromethyl)heptane (2) using a sodium-packed-bed reactor under continuous flow conditions. Thus, the resulting solution of 1 is free of elemental sodium and therefore suited for a range of synthetic applications. This new procedure avoids the storage of an alkylsodium and limits the handling of metallic sodium to a minimum. (2-Ethylhexyl)sodium (1) proved to be a very useful reagent and undergoes in-line Br/Na-exchanges as well as directed sodiations. The resulting arylsodium intermediates are subsequently trapped in batch with various electrophiles such as ketones, aldehydes, Weinreb-amides, imines, allyl bromides, disulfides and alkyl iodides. A reaction scale-up of the Br/Na-exchange using an in-line electrophile quench was also reported.
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Affiliation(s)
- Johannes H. Harenberg
- Department ChemieLudwig-Maximilians-Universität MünchenButenandtstrasse 5–13, Haus F81377MünchenGermany
| | - Niels Weidmann
- Department ChemieLudwig-Maximilians-Universität MünchenButenandtstrasse 5–13, Haus F81377MünchenGermany
| | - Alexander J. Wiegand
- Department ChemieLudwig-Maximilians-Universität MünchenButenandtstrasse 5–13, Haus F81377MünchenGermany
| | - Carla A. Hoefer
- Department ChemieLudwig-Maximilians-Universität MünchenButenandtstrasse 5–13, Haus F81377MünchenGermany
| | | | - Paul Knochel
- Department ChemieLudwig-Maximilians-Universität MünchenButenandtstrasse 5–13, Haus F81377MünchenGermany
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