Mechanochemical Approach for Air‐Tolerant and Extremely Fast Lithium‐Based Birch Reductions in Minutes

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(21)

Published: March 22, 2023

Birch reduction has been widely used in organic synthesis for over half a century as powerful method to dearomatize arenes into 1,4-cyclohexadiene derivatives. However, the conventional reaction using liquid ammonia requires laborious procedures ensure inert conditions and low temperatures. Although several ammonia-free modifications have reported, development of an operationally simple, efficient, scalable protocol remains challenge. Herein, we report lithium-based air without special operating ball-milling technique. This is characterized by its operational simplicity extremely short time (within 1 min), probably owing situ mechanical activation lithium metal, broad substrate scope, no requirement dry bulk solvents. The potential our flash also demonstrated efficient bioactive target molecules gram-scale synthesis.

Language: Английский

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Intermediates in Mechanochemical Reactions

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(14)

Published: Jan. 5, 2024

Abstract Mechanochemical reactions offer methodological and environmental advantages for chemical synthesis, constantly attracting attention within the scientific community. Besides unmistakable sustainability advantages, conditions under which mechanochemical occur, namely solventless conditions, sometimes facilitate isolation of otherwise labile or inaccessible products. Despite these limited knowledge exists regarding mechanisms types intermediates involved. Nevertheless, in an expanding number cases, ex situ monitoring techniques have allowed observation, characterization, reaction transformations. In this Minireview, we present a series examples reactive been detected spanning organic, organometallic, inorganic, materials chemistry. Many were stabilized by non‐covalent interactions, played pivotal role guiding We believe that uncovering understanding such instances, growing mechanochemistry community could find novel opportunities catalysis discover new while achieving simplification design.

Language: Английский

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Mechanochemical Organocatalysis: Do High Enantioselectivities Contradict What We Might Expect?

ChemSusChem, Journal Year: 2021, Volume and Issue: 15(2)

Published: Nov. 12, 2021

Ball mills input energy to samples by pulverising the contents of jar. Each impact on sample or wall jar results in an instantaneous transmission form a temperature and pressure increase (volume reduction). Conversely, enantioselective organocatalytic reactions proceed through perceived delicate well-organised transition states. Does there exist dichotomy idea mechanochemical organocatalysis? This Review provides survey literature reporting combination with ball milling conditions. Where possible, direct comparisons stirred solution, neat milled processes are drawn particular focus control stereoselectivity.

Language: Английский

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Mechanochemical Synthesis of Aryl Fluorides by Using Ball Milling and a Piezoelectric Material as the Redox Catalyst

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(39)

Published: July 31, 2023

Abstract Aryl fluorides are important structural motifs in many pharmaceuticals. Although the Balz–Schiemann reaction provides an entry to aryl from aryldiazonium tetrafluoroborates, it suffers drawbacks such as long time, high temperature, toxic solvent, gas release, and low functional group tolerance. Here, we describe a general method for synthesis of tetrafluoroborates using piezoelectric material redox catalyst under ball milling conditions presence Selectfluor. This approach effectively addresses aforementioned limitations. Furthermore, can be recycled multiple times. Mechanistic investigations indicate that this fluorination may proceed via radical pathway, Selectfluor plays dual role both source fluorine terminal reductant.

Language: Английский

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Lithium-Mediated Mechanochemical Cyclodehydrogenation

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(14), P. 8163 - 8175

Published: April 3, 2023

Cyclodehydrogenation is an essential synthetic method for the preparation of polycyclic aromatic hydrocarbons, heteroaromatic compounds, and nanographenes. Among many examples, anionic cyclodehydrogenation using potassium(0) has attracted chemists because its irreplaceable reactivity utility in obtaining rylene structures from binaphthyl derivatives. However, existing methods are difficult to use terms practicality, pyrophoricity, lack scalability applicability. Herein, we report development a lithium(0)-mediated mechanochemical reaction first time. This could be easily performed conventional easy-to-handle lithium(0) wire at room temperature, even under air, 1,1′-binaphthyl complete within 30 min afford perylene 94% yield. Using this novel user-friendly protocol, investigated substrate scope, mechanism, gram-scale synthesis. As result, remarkable applicability practicality over previous methods, as well limitations, were comprehensively studied by computational studies nuclear magnetic resonance analysis. Furthermore, demonstrated two-, three-, five-fold cyclodehydrogenations synthesis In particular, quinterrylene ([5]rylene or pentarylene), longest nonsubstituted molecular rylene, was synthesized

Language: Английский

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Assessing the Greenness of Mechanochemical Processes with the DOZN 2.0 Tool

ACS Sustainable Chemistry & Engineering, Journal Year: 2022, Volume and Issue: 10(16), P. 5110 - 5116

Published: March 10, 2022

As the demand increases for more sustainable chemical production, mechanochemical processes have been proposed as greener alternatives to traditional manufacturing methods. To support transition processes, quantitative assessment methods must be developed measure and compare greenness of processes. MilliporeSigma's DOZN 2.0 Green Chemistry Evaluator was utilized quantify adherence 12 Principles synthesis Active Pharmaceutical Ingredient (API) nitrofurantoin in batch continuous Through this analysis, SPEX mill twin-screw extrusion (TSE) were shown compared a commercial solution-based process. This conclusion result scores which demonstrated TSE having increased energy efficiency, improved resources use, reduced human environmental hazards other

Language: Английский

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Mechanochemically Induced Cross Dehydrogenative Coupling Reactions under Ball Milling

Advanced Synthesis & Catalysis, Journal Year: 2022, Volume and Issue: 364(15), P. 2462 - 2478

Published: June 16, 2022

Abstract Cross dehydrogenative coupling (CDC) reactions have become a convenient synthetic strategy for the synthesis of various (het)aromatic scaffolds. In recent times ball milling has emerged as powerful tool to perform in greener way. The current review highlights applications cross under towards useful molecules more efficient and manner. magnified image

Language: Английский

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Catalyst-free mechanochemistry as a versatile tool in synthetic chemistry: a review

Green Chemistry, Journal Year: 2023, Volume and Issue: 25(16), P. 6120 - 6148

Published: Jan. 1, 2023

This article presents a review of the reports on catalyst-free mechanochemical organic transformations and ability to initiate reactions that are extremely difficult/impossible occur is notable advancement process.

Language: Английский

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Opportunities and Challenges in Applying Solid‐State NMR Spectroscopy in Organic Mechanochemistry

Advanced Materials, Journal Year: 2023, Volume and Issue: 35(52)

Published: July 5, 2023

In recent years it is shown that mechanochemical strategies can be beneficial in directed conversions of organic compounds. Finding new reactions proved difficult, and due to the lack mechanistic understanding reaction events, respective efforts have mostly remained empirical. Spectroscopic techniques are crucial shedding light on these questions. this overview, opportunities challenges solid-state nuclear magnetic resonance (NMR) spectroscopy field mechanochemistry discussed. After a brief discussion basics high-resolution NMR under magic-angle spinning (MAS) conditions, seven for presented, ranging from ex situ approaches structurally elucidated products obtained by milling potential limitations approaches. Particular strengths NMR, instance differentiating polymorphs, NMR-crystallographic structure-determination protocols, or detecting weak noncovalent interactions molecular-recognition events employing proton-detected experiments at fast MAS frequencies,

Language: Английский

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Synthesis of α-ketothioamides with elemental sulfur under solvent-free conditions in a mixer mill

RSC Mechanochemistry, Journal Year: 2024, Volume and Issue: 1(1), P. 38 - 42

Published: Jan. 1, 2024

α-Ketothioamides are formed by a mechanochemical solvent-free Willgeroth–Kindler-type reaction starting from acetophenone derivatives, amines, and elemental sulfur.

Language: Английский

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