Exploring the role of solvent polarity in mechanochemical Knoevenagel condensation: <i>in situ</i> investigation and isolation of reaction intermediates

Scheurrell, Kerstin; B. Martins, Inês C.; Murray, Claire; Emmerling, Franziska

doi:10.1039/d3cp02883f

Cited by 2 publications

(2 citation statements)

References 43 publications

(73 reference statements)

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“…Systematic studies in solution [34] and under solventless conditions by mechanochemistry have demonstrated that Rh-based CÀ H activation involves the formation of reactive catalytic rhodacyclic intermediates. For example, in mechanochemical halogenations of 2-phenylpyridine (31) with N-halogen succinimides (NXS, X=Br, I) in the presence of [Cp*RhCl 2 ] 2 32 the involvement of rhodacycle 34 in the reaction was confirmed. [35] Mechanosynthesis of 34 could be accomplished by reacting 31 and 32 with sodium acetate (NaOAc) in a ball mill (Scheme 12).…”

Section: Intermediates In Mechanochemical C-h and B-h Activation And ...mentioning

confidence: 98%

Intermediates in Mechanochemical Reactions

Ardila‐Fierro,

Hernández

2024

Angew Chem Int Ed

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

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Section: Intermediates In Mechanochemical C-h and B-h Activation And ...mentioning

confidence: 98%

Intermediates in Mechanochemical Reactions

Ardila‐Fierro,

Hernández

2024

Angew Chem Int Ed

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show abstract

“…Although, to be precise, in the previous example the detection of intermediates before the formation of the molecular product 20 did not occur, in a related study in 2023 the same research group managed to observe, isolate, and determine the structure of an intermediate in the Knoevenagel condensation between 19 and p-nitrobenzaldehyde (21) (Scheme 9a). [31] Monitoring the milling of 19 and 21 by in situ Raman spectroscopy and PXRD enabled the detection of (2-(hydroxyl(4-nitrophenyl)methyl)malononitrile ( 22) that corresponds to the addition product, an intermediate, which upon elimination of water led to the formation of the corresponding Knoevenagel product 23.…”

Section: Intermediates In Mechanochemical Knoevenagel Reactionsmentioning

confidence: 99%