Metal-catalyzed organic reactions using mechanochemistry

Hernández, José G.; Friščić, Tomislav

doi:10.1016/j.tetlet.2015.03.135

Cited by 184 publications

(82 citation statements)

References 145 publications

(98 reference statements)

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“…As this procedure may influence the reaction, is too slow and often unreliable, and hinders an appropriate understanding of the mechanisms responsible for the reaction, new techniques for online-analytics were recently established, such as powder X-ray diffraction (PXRD). [13] This challenge was addressed by direct sublimation of the product from the solid reaction mixture, e.g. Though, this technique is not applicable for amorphous solids; Raman spectroscopy turned out to be a useful tool to follow organic reactions in the amorphous state and to understand the mechanisms involved.…”

Section: Resultsmentioning

confidence: 99%

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Organic Synthesis without Conventional Solvents

Obst

König

2018

Eur J Org Chem

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Organic synthesis without an organic solvent is still the exception. In this microreview, we discuss and compare different synthetic methods that proceed in the absence of conventional organic solvents. This includes solvent‐free methods in solids (mechanochemistry and solid‐state photochemistry), and in neat liquids (thermal and photocatalytic), as well as the application of unconventional solvents, such as ionic liquids and deep‐eutectic solvents. The different approaches are briefly introduced and examples illustrate their specific advantages, followed by a critical discussion of their limitations. Some methods have the intrinsic benefits of solvent‐free operation, such as avoiding solubility problems and side‐reactions with the solvent. However, every method has specific advantages and the demand of the synthetic application is crucial for selecting the best technique.

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Section: Resultsmentioning

confidence: 99%

“…In this review, we focus on the reaction of solid reactants. [13] Since the processes caused by the input of mechanical energy are rather complex, the mechanisms involved in a mechanochemical reaction are not fully understood.…”

Section: Definition and Mechanismmentioning

confidence: 99%

Organic Synthesis without Conventional Solvents

Obst

König

2018

Eur J Org Chem

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“…It is perhaps not surprising that when mechanochemical activation is used with alkaline earth reagents, a nonstoichiometric product such as the organoberyllate 1 is formed, as grinding and milling environments are often far from equilibrium [38][39][40][41]. However, the fact that 1 is also generated in hexanes indicates how non-ethereal synthesis can reveal features of reactions that are obscured when they are conducted in coordinating solvents.…”

Section: Discussionmentioning

confidence: 99%

Symmetric Assembly of a Sterically Encumbered Allyl Complex: Mechanochemical and Solution Synthesis of the Tris(allyl)beryllate, K[BeA′3] (A′ = 1,3-(SiMe3)2C3H3)

et al. 2017

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Abstract:The ball milling of beryllium chloride with two equivalents of the potassium salt of bis(1,3-trimethylsilyl)allyl anion, K[A ] (A = [1,3-(SiMe 3 ) 2 C 3 H 3 ]), produces the tris(allyl)beryllate K[BeA' 3 ] (1) rather than the expected neutral BeA' 2 . The same product is obtained from reaction in hexanes; in contrast, although a similar reaction conducted in Et 2 O was previously shown to produce the solvated species BeA' 2 (OEt 2 ), it can produce 1 if the reaction time is extended (16 h). The tris(allyl)beryllate is fluxional in solution, and displays the strongly downfield 9 Be NMR shift expected for a three-coordinate Be center (δ22.8 ppm). A single crystal X-ray structure reveals that the three allyl ligands are bound to beryllium in an arrangement with approximate C 3 symmetry (Be-C (avg) = 1.805(10) Å), with the potassium cation engaging in cation-π interactions with the double bonds of the allyl ligands. Similar structures have previously been found in complexes of zinc and tin, i.e., M[M A 3 L] (M = Zn, M = Li, Na, K; M = Sn, M = K; L = thf). Density functional theory (DFT) calculations indicate that the observed C 3 -symmetric framework of the isolated anion ([BeA 3 ] − ) is 20 kJ·mol −1 higher in energy than a C 1 arrangement; the K + counterion evidently plays a critical role in templating the final conformation.

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“…84 In recent years, mechanochemistry has also constituted a developing field of interest in organic synthesis, 85,86 thus ball-milling has been successfully employed in the synthesis of peptides and aromatic amides, 87 in the preparation of substituted hydantoins from dipeptides 88 in carbon-heteroatom bond forming reactions, in the synthesis of heterocycles, 89 in the synthesis of Ugi 4-CR and Passerini 3-CR adducts, 90 in cross-coupling reactions as well as in other metal-catalyzed organic processes. 91 Likewise, asymmetric organocatalysis can also take advantage of mechanochemical tools to carry out solvent free (or minimal solvent versions) of existing reactions which proceed via enamine formation among other activation mechanisms. 92 In this regard, it should be noted the pioneering work implemented by Bolm and co-workers, 93 and Nájera and co-workers 94 in aldol and Michael reactions under ball-milling activation.…”

Section: Organocatalysis Via Proline Dipeptide Derivatives Assisted Bmentioning

confidence: 99%

Determination of Enantioselectivities by Means of Chiral Stationary Phase HPLC in Order to Identify Effective Proline-Derived Organocatalysts

Vargas-Caporali¹,

Juaristi²

2017

J. Braz. Chem. Soc.

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The pyrrolidine fragment is a privileged scaffold within chiral ligands employed in coordination complexes exhibiting catalytic activity in asymmetric reactions and, more recently, as enantioselective organocatalysts per se. Likewise, the employment of (S)-proline as starting material constitutes the most direct form to synthesize those chiral derivatives. Afterwards, a preliminary evaluation of the catalytic performance of proline-derived compounds consists of screening many prochiral substrates in well standardized model reactions such as Michael additions and Mannich reactions, with the aim of identifying "broad spectrum" catalysts for more complex synthetic applications. Therefore, a central part of this process involves the fast and direct measurement of enantioselectivities of optically active adducts. The growing development of chiral stationary phases and thus, the wide commercial availability of chiral columns have consolidated high performance liquid chromatography (HPLC) as the preferred technique to identify the most effective catalysts.

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Metal-catalyzed organic reactions using mechanochemistry

Cited by 184 publications

References 145 publications

Organic Synthesis without Conventional Solvents

Organic Synthesis without Conventional Solvents

Symmetric Assembly of a Sterically Encumbered Allyl Complex: Mechanochemical and Solution Synthesis of the Tris(allyl)beryllate, K[BeA′3] (A′ = 1,3-(SiMe3)2C3H3)

Determination of Enantioselectivities by Means of Chiral Stationary Phase HPLC in Order to Identify Effective Proline-Derived Organocatalysts

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