The Heck reaction under ball-milling conditions

Tullberg, Erik; Peters, Dan; Frejd, Torbjörn

doi:10.1016/j.jorganchem.2004.06.045

Cited by 111 publications

(69 citation statements)

References 13 publications

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“…McKissic et al observed a temperature of 50°C after 1 h milling in a Spex mixer mill and Takacs and McHenry reported milling ball temperatures of 66°C [12,13]. Comparably higher temperatures can be reached in planetary ball mills (PBMs), where temperatures from 60 to 600°C can be measured, depending on the type of PBM, the grinding stock, the grinding material and the filling degree [5,13,14].…”

Section: Introductionmentioning

confidence: 99%

Temperature progression in a mixer ball mill

2016

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The influence of the operating frequency, the milling ball and grinding stock filling degree, the material of the milling balls and beakers, the milling ball diameter and the size of the milling beakers on the temperature increase inside the milling beakers in a mixer ball mill was investigated. These parameters influence the temperature progression and the equilibrium temperature of the system. The grinding stock filling degree with regard to the void volume in the milling ball package showed huge influence on the heating rate and the equilibrium temperature. In this context, the behavior of the temperature progression changes if the complete void volume is filled with the grinding stock.

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Section: Introductionmentioning

confidence: 99%

Temperature progression in a mixer ball mill

2016

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“…[18,19] In synthetic organic chemistry it has seldomly been used, and the few reported examples include the functionalization of fullerenes, [20] the reductive benzylation of malonitrile, [21] the protection of amines, [22a] Knoevenagel [22b] and aldol [23] condensations, Michael additions, [22b] the preparation of phosphorus ylides, [24] the oxidative coupling of 2-naphthol, [25] and Heck-type cross-coupling reactions. [26] On that basis, a study was initiated focussing on the investigation of asymmetric organocatalytic reactions under (solvent-free) ball-milling conditions. [27] Besides enantioselective anhydride openings mediated by cinchona alkaloids, [28] proline-catalyzed asymmetric aldol reactions became research targets.…”

Section: Introductionmentioning

confidence: 99%

A Highly Efficient Asymmetric Organocatalytic Aldol Reaction in a Ball Mill

Rodrı́guez¹,

Bruckmann²,

Bolm³

2007

Chemistry A European J

235

118

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Anti-aldol products with up to >99 % enantiomeric excess (ee) have been obtained by proline catalysis in excellent yields under experimentally simple solvent-free conditions. Efficient mixing of all the components is accomplished by applying a mechanochemical technique (ball milling). The catalysis is air and moisture tolerant and can be performed with non-purified starting materials. Even mixtures of solely solid compounds react, giving (mostly solid) products through a partially homogeneous (honey-like) intermediate melt. Since the reactant ratio is almost 1:1 (avoiding the common excess of ketone), the product isolation is easy leading to high aldol product yields.

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“…In order to find a more efficient method, in 2004 Frejd and co-workers investigated a solvent-free ball milling variant for the coupling of aryl halides with amidoacrylates to afford substituted dehydroalanines (Scheme 23). [77] In this study, the methyl and the benzyl esters of 2-tert-butoxycarbonylaminoacrylic acid (78) were ball-milled in a planetary ball mill (800 rpm, 1 h) with various aryl halides 79 under argon in a stainless steel vessel containing eight stainless steel balls. In general, aryl halides possessing electron-donating groups or with no other substitution proved to be the best coupling partners.…”

Section: The Heck-jeffery Reactionmentioning

confidence: 99%