Mechanochemical solid state synthesis of copper(I)/NHC complexes with K₃PO₄

• Ina Remy-Speckmann,
• Birte M. Zimmermann,
• Mahadeb Gorai,
• Martin Lerch and
• Johannes F. Teichert

Beilstein J. Org. Chem. 2023, 19, 440–447, doi:10.3762/bjoc.19.34

• , Germany 10.3762/bjoc.19.34 Abstract A protocol for the mechanochemical synthesis of copper(I)/N-heterocyclic carbene complexes using cheap and readily available K3PO4 as base has been developed. This method employing a ball mill is amenable to typical simple copper(I)/NHC complexes but also to a

• been shown to be active in a variety of reduction/hydrogenation transformations employing dihydrogen as terminal reducing agent. Keywords: ball mill; bifunctional catalysis; catalytic hydrogenations; copper; mechanochemical synthesis; N-heterocyclic carbenes; Introduction Prominent goals of green

• , utilizing Cu2O for a “built-in base” approach did not give complex 5 (Table 1, entry 6). Since our attempts to establish direct synthetic routes to 5 from 3 in liquid state were not fruitful, we turned our attention to the mechanochemical synthesis of bifunctional catalyst 5, based on two recent reports on

Mechanochemical synthesis of unsymmetrical salens for the preparation of Co–salen complexes and their evaluation as catalysts for the synthesis of α-aryloxy alcohols via asymmetric phenolic kinetic resolution of terminal epoxides

• Shengli Zuo,
• Shuxiang Zheng,
• Jianjun Liu and
• Ang Zuo

Beilstein J. Org. Chem. 2022, 18, 1416–1423, doi:10.3762/bjoc.18.147

• , University of Illinois at Chicago, Chicago, Illinois 60612, United States 10.3762/bjoc.18.147 Abstract In this paper, we report the mechanochemical synthesis of unsymmetrical salens using grinding and ball milling technologies, respectively, both of which were afforded in good yield. The chelating effect of

• ]. Inspired by the mechanochemical chemistry technology to simplify chemical processes and eliminate the use of organic solvents, salen compounds have been synthesized by the “green” grinding strategy previously [30][31][32][33][34][35][36][37][38][39]. Herein, we report a one-pot two-step mechanochemical

• synthesis of unsymmetrical salens for the preparation of Co–salen complexes and their evaluation as catalyst for the synthesis of α-aryloxy alcohols through the phenolic KR of terminal epoxides (Scheme 1). Indeed, advantages to break the C2-symmetry in Co–salen complexes were reported before [23][40]. In

From amines to (form)amides: a simple and successful mechanochemical approach

• Federico Casti,
• Rita Mocci and
• Andrea Porcheddu

Beilstein J. Org. Chem. 2022, 18, 1210–1216, doi:10.3762/bjoc.18.126

• ]. In this work, we aimed to set compatible conditions to access formamides, envisioning the possibility of generating the isocyanide in a one-pot, two-step reaction. However, to the best of our knowledge, despite the notable improvement in the mechanochemical synthesis of the amide moiety [44][48][49

Mechanochemical bottom-up synthesis of phosphorus-linked, heptazine-based carbon nitrides using sodium phosphide

• Blaine G. Fiss,
• Georgia Douglas,
• Michael Ferguson,
• Jorge Becerra,
• Jesus Valdez,
• Trong-On Do,
• Tomislav Friščić and
• Audrey Moores

Beilstein J. Org. Chem. 2022, 18, 1203–1209, doi:10.3762/bjoc.18.125

• , mechanochemical synthesis of phosphorus-bridged heptazine-based carbon nitrides (g-h-PCN). The structure of these materials was determined through a combination of powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), 31P magic angle spinning nuclear magnetic resonance (MAS NMR), density

• heptazine subunits. The introduction of phosphorus linkages reduced photoluminescent recombination and improved exciton lifetimes, when compared to nitrogen-linked g-CN. Overall, this supports future investigations of the room-temperature mechanochemical synthesis of heteroatom containing carbons as well as

• . 31P MAS NMR of a) g-h-PCN and b) g-h-PCN300. Asterisks denote spinning sidebands. Calculated structures for a) corrugated (edge facing), b) corrugated (single layer), c) layered g-h-PCN and d) phosphine paddlewheel. a) Mechanochemical synthesis of g-PCN from sodium phosphide and trichlorotriazine

Palladium-catalyzed solid-state borylation of aryl halides using mechanochemistry

• Koji Kubota,
• Emiru Baba,
• Tamae Seo,
• Tatsuo Ishiyama and
• Hajime Ito

Beilstein J. Org. Chem. 2022, 18, 855–862, doi:10.3762/bjoc.18.86

• , mechanochemical synthesis using ball milling has attracted considerable attention as an efficient solvent-free synthetic technique [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Notably, the strong mechanical agitation provided by ball milling enables efficient solid-state organic

DDQ in mechanochemical C–N coupling reactions

• Shyamal Kanti Bera,
• Rosalin Bhanja and
• Prasenjit Mal

Beilstein J. Org. Chem. 2022, 18, 639–646, doi:10.3762/bjoc.18.64

• mechanochemical C–N coupling reactions using DDQ. The newly formed C–N bonds are shown as red lines for clarity. a) The intramolecular C(sp2)-H amidation leading to 1,2-disubstituted benzimidazoles. b) One-pot coupling to synthesize substituted quinazolin-4(3H)-ones. Scope of the mechanochemical synthesis of

Particle size effect in the mechanically assisted synthesis of β-cyclodextrin mesitylene sulfonate

• Stéphane Menuel,
• Sébastien Saitzek,
• Eric Monflier and
• Frédéric Hapiot

Beilstein J. Org. Chem. 2020, 16, 2598–2606, doi:10.3762/bjoc.16.211

• higher selectivity towards the mono-substituted β-CDMts products, rendering the mechanochemical synthesis of these products advantageous over the synthesis carried out in solution. The synthesis of β-CDMts is not amenable to the facile and systematic determination of a unique solid-state kinetics model

The B & B approach: Ball-milling conjugation of dextran with phenylboronic acid (PBA)-functionalized BODIPY

• Patrizia Andreozzi,
• Lorenza Tamberi,
• Elisamaria Tasca,
• Gina Elena Giacomazzo,
• Marta Martinez,
• Mirko Severi,
• Marco Marradi,
• Stefano Cicchi,
• Sergio Moya,
• Giacomo Biagiotti and
• Barbara Richichi

Beilstein J. Org. Chem. 2020, 16, 2272–2281, doi:10.3762/bjoc.16.188

• range of biomolecules: amino acids [8], peptides [9], glycosides [10], nucleosides/nucleotides [11], and lipids [12]. Also, protein-based nano-bio-conjugates [13] have been prepared by ball milling, retaining the native properties of the proteins after mechanochemical synthesis. Boronic acids and their

• properties for biofunctionalization [26] and that displays a PBA moiety conjugated to a BODIPY core. The mechanochemical synthesis avoids the use of a large excess of 1 in the reaction mixture. Accordingly, reactions following either mechanochemical or solution-based protocols were carried out using a

Halide metathesis in overdrive: mechanochemical synthesis of a heterometallic group 1 allyl complex

• Ross F. Koby,
• Nicholas R. Rightmire,
• Nathan D. Schley,
• Timothy P. Hanusa and
• William W. Brennessel

Beilstein J. Org. Chem. 2019, 15, 1856–1863, doi:10.3762/bjoc.15.181

• '] to CsI, and the predicted result from Equation 5, assuming complete reaction, would have been either pure [CsA'] or the heterometallic [CsK2A'3]. That neither of these outcomes was observed, and a non-stoichiometric product was obtained is actually not uncommon in mechanochemical synthesis, and can

Mechanochemical synthesis of hyper-crosslinked polymers: influences on their pore structure and adsorption behaviour for organic vapors

• Sven Grätz,
• Sebastian Zink,
• Hanna Kraffczyk,
• Marcus Rose and
• Lars Borchardt

Beilstein J. Org. Chem. 2019, 15, 1154–1161, doi:10.3762/bjoc.15.112

Extending mechanochemical porphyrin synthesis to bulkier aromatics: tetramesitylporphyrin

• Qiwen Su and
• Tamara D. Hamilton

Beilstein J. Org. Chem. 2019, 15, 1149–1153, doi:10.3762/bjoc.15.111

• methods. Yields of the mechanochemical synthesis were found to increase slightly upon longer exposure to an organic oxidizing agent in solution. This indicates that the mechanochemical condensation step may be more successful than initially realized. This work shows that mechanochemistry is a successful

• conditions, while the sealed-bomb reaction products are heavily contaminated with chlorins [27][28][29], byproducts that contain two more hydrogens than the porphyrin, and which easily undergo chemical oxidation to yield porphyrin. In contrast, since the no-solvent-added mechanochemical synthesis takes place

• instantaneously [11]. In the case of the mechanochemical synthesis, the results show that a longer oxidation time results reproducibly in a somewhat higher yield (Table 1), although the isolated yield remains around 5%. Identity and purity of TMP was confirmed by UV–vis and 1H NMR spectroscopy (see Supporting

Mechanochemical synthesis of poly(trimethylene carbonate)s: an example of rate acceleration

• Sora Park and
• Jeung Gon Kim

Beilstein J. Org. Chem. 2019, 15, 963–970, doi:10.3762/bjoc.15.93

• can now be obtained through green mechanochemical synthesis. In addition to the general merits of mechanochemistry, such as being solvent-free and resulting in high conversions, we herein explore rate acceleration under ball-milling conditions while the conventional solution-state synthesis suffer

• brief ball milling of monomer and base [10]. The remarkable reactivity exemplified that the general concepts of mechanochemical synthesis are applicable to polymerization reactions. Other examples of polymer syntheses have followed. The Borchardt research team reported the efficient mechanochemical

• synthesis of poly(azomethine) and poly(phenylene) [11][12]. Our group also contributed to this area by developing a ball-milling promoted high-molecular weight poly(lactic acid) synthesis [13][14] and a solvent-free post-polymerization modification of functional polystyrenes [15]. The Friščić team also

Mechanochemistry of supramolecules

• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2019, 15, 881–900, doi:10.3762/bjoc.15.86

• mixing [22][23], ultrasound [24], etc. as alternative energy sources to replace common laboratory techniques [25]. Among them, especially mechanochemical synthesis [26][27][28][29] has gained popularity due to its advantage over conventional solution-based methods [30]. The process is highly beneficial

• ]. Subsequently, compound 2 underwent substitution with α,α’-dibromo-o-xylene to create the nickel(II) complex 3 [54]. In 2014, James and co-workers reported a one-pot two-step mechanochemical synthesis of metal complexes 7 (Figure 3). First, the salen-type ligand 6 was synthesized from o-hydroxybenzaldehyde (4

• acetic acid (for liquid-assisted grinding, LAG) led to the regioselective C–H activation (Figure 5) [58]. In 2008, the mechanochemical synthesis of both [2]- and [4]rotaxanes was reported by Chiu and co-workers. The reactions led to high yields of the products 12 and 13 under solvent-free conditions at a

Synthesis of acylglycerol derivatives by mechanochemistry

• Karen J. Ardila-Fierro,
• Andrij Pich,
• Marc Spehr,
• José G. Hernández and
• Carsten Bolm

Beilstein J. Org. Chem. 2019, 15, 811–817, doi:10.3762/bjoc.15.78

• Chemosensation, Institute for Biology II, RWTH Aachen University, D-52074 Aachen, Germany 10.3762/bjoc.15.78 Abstract In recent times, many biologically relevant building blocks such as amino acids, peptides, saccharides, nucleotides and nucleosides, etc. have been prepared by mechanochemical synthesis. However

• mechanochemical synthesis of Cu–carbene complexes from N,N-diarylimidazolium salts, dioxygen and metallic copper [40], which involved a mechanochemical reaction with gaseous reagents [41]. Pleasingly, this time the reaction afforded product 4a, although the yield remained low (59%), even after three hours of

Assembly of fully substituted triazolochromenes via a novel multicomponent reaction or mechanochemical synthesis

• Robby Vroemans,
• Yenthel Verhaegen,
• My Tran Thi Dieu and
• Wim Dehaen

Beilstein J. Org. Chem. 2018, 14, 2689–2697, doi:10.3762/bjoc.14.246

• intermediate 3-nitro-2H-chromenes with organic azides in a one-pot two-step sequence. The triazolochromenes were formed with complete regioselectivity and new biologically relevant structures were synthesized via extension of the developed procedure and via postfunctionalization. The mechanochemical synthesis

The mechanochemical synthesis of quinazolin-4(3H)-ones by controlling the reactivity of IBX

• Md Toufique Alam,
• Saikat Maiti and
• Prasenjit Mal

Beilstein J. Org. Chem. 2018, 14, 2396–2403, doi:10.3762/bjoc.14.216

• ; contact explosive; IBX; mechanochemical synthesis; quinazolin-4(3H)-one; Introduction An iodine and ammonia mixture is a well-known contact explosive due to formation of NI3 [1]. Similarly, hypervalent iodines as oxidizing compounds [2] react violently with amines under solvent-free conditions [3

Exploring mechanochemistry to turn organic bio-relevant molecules into metal-organic frameworks: a short review

• Vânia André,
• Sílvia Quaresma,
• João Luís Ferreira da Silva and
• M. Teresa Duarte

Beilstein J. Org. Chem. 2017, 13, 2416–2427, doi:10.3762/bjoc.13.239

• ) when grinding with three or four equiv of water, respectively (Figure 4) [136][137]. This method was further applied to the mechanochemical synthesis of porous materials with introduced auxiliary ligands. These would allow for coordination to zinc in order to generate pillared MOFs, that could be used

• , without the need for bulky solvents, external bases or acids and high temperatures, all required in the conventional synthetic procedure [139]. Even though MOF-5 has not yet been tested for the incorporation of drugs, using the same linker, Xu et al. unveiled in 2016 the mechanochemical synthesis of MIL

• administration of a high dosage of ibuprofen [141]. The mechanochemical synthesis was expanded by Beldon et al. to the synthesis of a very different family of metal-organic materials, the zeolitic imidazolate frameworks (ZIFs) [8]. ZIFs exploit a combination of metal ions and imidazolate linkers to build the 3D

Solvent-free copper-catalyzed click chemistry for the synthesis of N-heterocyclic hybrids based on quinoline and 1,2,3-triazole

• Martina Tireli,
• Silvija Maračić,
• Stipe Lukin,
• Marina Juribašić Kulcsár,
• Dijana Žilić,
• Mario Cetina,
• Ivan Halasz,
• Silvana Raić-Malić and
• Krunoslav Užarević

Beilstein J. Org. Chem. 2017, 13, 2352–2363, doi:10.3762/bjoc.13.232

• catalyst (method 2a); and b) mechanochemical formation of triazole 5 by method 2b using CuI/DIPEA catalyst. a) In situ Raman monitoring for mechanochemical synthesis of 5 using brass balls and PMMA reaction vessel. b) Selected Raman spectra from panel a) highlighting the slow transformation of the alkyne

The effect of milling frequency on a mechanochemical organic reaction monitored by in situ Raman spectroscopy

• Patrick A. Julien,
• Ivani Malvestiti and
• Tomislav Friščić

Beilstein J. Org. Chem. 2017, 13, 2160–2168, doi:10.3762/bjoc.13.216

• milling frequency on the course of a mechanochemical organic reaction conducted using a vibratory shaker (mixer) ball mill. The use of in situ Raman spectroscopy for real-time monitoring of the mechanochemical synthesis of a 2,3-diphenylquinoxaline derivative revealed a pronounced dependence of chemical

• reactivity on small variations in milling frequency. In particular, in situ measurements revealed the establishment of two different regimes of reaction kinetics at different frequencies, providing tentative insight into processes of mechanical activation in organic mechanochemical synthesis. Keywords

• mechanochemical synthesis of a MOF from ZnO and imidazole in the presence of a small amount of N,N-dimethylformamide [41]. This study revealed reaction kinetics consistent with a 2nd order reaction rate law, rationalized through a “pseudo-fluid” reaction model in which the rate-determining factor is the frequency

Main group mechanochemistry

• Agota A. Gečiauskaitė and
• Felipe García

Beilstein J. Org. Chem. 2017, 13, 2068–2077, doi:10.3762/bjoc.13.204

• group compounds and frameworks. Keywords: ball milling; main group; mechanochemical synthesis; mechanochemistry; Introduction The original mainspring for the current expansion of solid state methodologies is the need for cleaner, safer and sustainable chemical transformations – particularly since raw

• have become increasingly popular (with recent reviews on mechanochemical synthesis by Rightmire and Hanusa [11], Do and Friščić [12], Hernández and Bolm [13], Wang [14], and James et al. [2]) there are relatively few studies concerning main group elements. The development of new and novel main group

• orthogonality of multistep mechanochemical synthesis and widening its applicability. A significant example of the transformative potential of mechanochemistry is its ability to produce metal complexes directly from bulk metal or metal oxides [66]. Within this context, the LAG synthesis of germanes (GeR4

Mechanochemical Knoevenagel condensation investigated in situ

• Sebastian Haferkamp,
• Franziska Fischer,
• Werner Kraus and
• Franziska Emmerling

Beilstein J. Org. Chem. 2017, 13, 2010–2014, doi:10.3762/bjoc.13.197

• reactions with quantitative yields of the final product are possible, rendering the use of solvents and work-up procedures unnecessary [3][15]. The mechanochemical synthesis can effect carbon–carbon and carbon–heteroatom covalent bonds, coordinating bonds between metal and ligands, and non-covalent

New bio-nanocomposites based on iron oxides and polysaccharides applied to oxidation and alkylation reactions

• Daily Rodríguez-Padrón,
• Alina M. Balu,
• Antonio A. Romero and
• Rafael Luque

Beilstein J. Org. Chem. 2017, 13, 1982–1993, doi:10.3762/bjoc.13.194

• object of most research from our group over the past years [10][20][21][22]. One of the main challenges in the field of catalysis is the preparation of new materials to replace the traditional catalysts quickly, cheaply and efficiently [5]. In this regard, mechanochemical synthesis has become one of the

One-pot multistep mechanochemical synthesis of fluorinated pyrazolones

• Joseph L. Howard,
• William Nicholson,
• Yerbol Sagatov and
• Duncan L. Browne

Beilstein J. Org. Chem. 2017, 13, 1950–1956, doi:10.3762/bjoc.13.189

• Joseph L. Howard William Nicholson Yerbol Sagatov Duncan L. Browne School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, UK 10.3762/bjoc.13.189 Abstract Solventless mechanochemical synthesis represents a technique with improved sustainability metrics compared to

• small range of compounds. Conclusion In summary, we have developed a one-pot, two-step mechanochemical synthesis of fluorinated pyrazolones. The experiments provide a logical approach to multistep solventless synthesis under milling conditions and more broadly will assist in the conversion of other

• physical form in the one-pot two-step mechanochemical procedure. Optimised conditions for the one-pot synthesis. Substrate scope of the one-pot, 2 step mechanochemical synthesis (isolated yields). a1 equiv Selectfluor used. Optimisation of pyrazolone formation. Optimisation of pyrazolone fluorination

Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

• mechanochemistry [31], mechanistic aspects [32], mechanochemical synthesis of inorganic material [33], co-crystals [34], metal–ligand complexes [35], metal organic frameworks [36], polymers [37], etc. are well documented in seminal reviews and will not be discussed here. The organic mechanochemistry has remained

• are mixed to finely powdered form for better mixing. The ball-milling chemistry can better be conceived as the updated and sophisticated version of traditional grinding chemistry [38]. Mechanochemical synthesis of C–C bond More atom economic, energy efficient, time efficient and mild syntheses of C–C

• Reaction Pecharsky and co-workers reported the solvent-free mechanochemical synthesis of phosphonium salts [54] and phosphorus ylides [55] in the presence of the weak base K2CO3. Mechanochemically prepared phosphorous ylide from triphenylphosphine in presence of K2CO3 was utilized for a one-pot solvent

Influence of the milling parameters on the nucleophilic substitution reaction of activated β-cyclodextrins

• László Jicsinszky,
• Kata Tuza,
• Giancarlo Cravotto,
• Andrea Porcheddu,
• Francesco Delogu and
• Evelina Colacino

Beilstein J. Org. Chem. 2017, 13, 1893–1899, doi:10.3762/bjoc.13.184

• ]. Despite the longer milling times, using less balls allow outcomes to be improved [14]. This work takes the above-mentioned results as a base from which to address the mechanochemical synthesis of 6I-monoazido-6I-monodeoxy-β-CD and 6I-S-monodeoxy-6I-monothiouronium-β-CD tosylate (TU-β-CD), an important CD