Solvent-free mechanochemical and one-pot reductive benzylizations of malononitrile and 4-methylaniline using Hantzsch 1,4-dihydropyridine as the reductant

Zhang, Ze; Gao, Jie; Xia, Jingjing; Wang, Guan‐Wu

doi:10.1039/b502662h

Cited by 72 publications

(33 citation statements)

References 25 publications

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“…The 1 H and 13 C spectra of the products 3a [33], 3b [34], 3c [35], 3d [36], 3e [37], 3f [38], 3j [39], 3m [40] and 3o [41], 3r [42,43] and 3s [22] were consistent with those reported.…”

Section: Spectral Datasupporting

confidence: 89%

Gallium(III) Triflate Catalyzed Direct Reductive Amination of Aldehydes

Prakash

Mathew

et al. 2010

Catal Lett

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Direct hydroamination of aldehydes and ketones provides one-step entry into desired a-aminoalkane derivatives which are important synthons for many biologically active molecules. The reductive amination of aldehydes in the presence of silanes has been effectively promoted by Ga(OTf) 3 as a catalyst. Mild conditions, easy work-up and high purity of products with excellent yields are the major advantages of this method.

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“…The 1 H and 13 C spectra of the products 3a [33], 3b [34], 3c [35], 3d [36], 3e [37], 3f [38], 3j [39], 3m [40] and 3o [41], 3r [42,43] and 3s [22] were consistent with those reported.…”

Section: Spectral Datasupporting

confidence: 89%

Gallium(III) Triflate Catalyzed Direct Reductive Amination of Aldehydes

Prakash

Mathew

et al. 2010

Catal Lett

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“…When molecular solids aggregate and adhere to the walls of the mill at very high viscosity, this process becomes inefficient. Recently, ball-milling without temperature control and increased milling speeds for the so-called "mechanical activation" of molecular reactions [22,23] increased such difficulties even further and excessive milling times of up to 20 h [24] or up to several days were required, [25] although the authors claimed to have performed "mechanochemistry". Rather, an adjustment of the temperature and decrease in the mechanical impact to obtain reasonably short reaction times by a better mixing of the reagents with an optimized kneading, if not simply melting, would perhaps have been a better choice.…”

Section: Resultsmentioning

confidence: 99%

Kneading Ball‐Milling and Stoichiometric Melts for the Quantitative Derivatization of Carbonyl Compounds with Gas–Solid Recovery

et al. 2009

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A ray of hope for the environment is sustainable and green synthesis without the production of (toxic) waste. Solvent-free stoichiometric melting or kneading ball-milling reactions of aldehydes or ketones with carbonyl reagents yields arylhydrazones and oximes in quantitative yield. The carbonyl compounds can be quantitatively recovered from the imino derivatives by using gaseous NO(2).An effective methodology of kneading with a ball mill under temperature control was used for the stoichiometric quantitative preparation of synthetically versatile oximes and 2,4-dinitrophenylhydrazones from low-melting aldehydes and ketones. Also, a large number of phenylhydrazones are obtained by safe stoichiometric quantitative melt reactions. Advantages of this technique are short reaction times, eco-friendliness, and ease of handling under solvent-free conditions, as no waste-producing purifying workup is necessary. The different reactivities of aldehydes and ketones allow for easy separation of mixtures containing aldehydes and ketones. Furthermore, a new effective, gas-solid deprotection methodology for oximes was developed, using nitrogen dioxide as the reagent under solvent-free conditions to recover the aldehydes or ketones. The corresponding aldehydes were obtained free of overoxidized acids in quantitative yields.

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“…Ball milling has widely been applied for the grinding of minerals into fine particles and for the preparation and modification of inorganic solids. [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.…”

Section: Introductionmentioning

confidence: 99%

A Highly Efficient Asymmetric Organocatalytic Aldol Reaction in a Ball Mill

Rodrı́guez¹,

Bruckmann²,

Bolm³

2007

Chemistry A European J

238

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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Solvent-free mechanochemical and one-pot reductive benzylizations of malononitrile and 4-methylaniline using Hantzsch 1,4-dihydropyridine as the reductant

Abstract: Under mechanical milling conditions, direct reductive benzylizations of malononitrile and 4-methylaniline by aromatic aldehydes were achieved using a Hantzsch 1,4-dihydropyridine as the reductant.

Cited by 72 publications

References 25 publications

Gallium(III) Triflate Catalyzed Direct Reductive Amination of Aldehydes

Gallium(III) Triflate Catalyzed Direct Reductive Amination of Aldehydes

Kneading Ball‐Milling and Stoichiometric Melts for the Quantitative Derivatization of Carbonyl Compounds with Gas–Solid Recovery

A Highly Efficient Asymmetric Organocatalytic Aldol Reaction in a Ball Mill

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