High-speed vibration-milling-promoted synthesis of symmetrical frameworks containing two or three pyrrole units

• Marco Leonardi,
• Mercedes Villacampa and
• J. Carlos Menéndez

Beilstein J. Org. Chem. 2017, 13, 1957–1962, doi:10.3762/bjoc.13.190

• achieved by a different approach involving the homodimerization of 1-allyl- or 1-homoallylpyrroles by application of cross-metathesis chemistry. Keywords: diversity-oriented synthesis; mechanochemistry; multicomponent reactions; pyrroles; solvent-free synthesis; Introduction Symmetrical molecules formed

• disconnection employed and the structural diversity introduced at the three reaction components is summarized in Scheme 1. Our procedure involves the use of mechanochemistry, which deals with reactions promoted by mechanical energy and is emerging in recent years as a versatile tool that allows solvent-free

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

• solvent-based processes. Herein, we describe a methodical process to run one solventless reaction directly into another through multistep mechanochemistry, effectively amplifying the solvent savings. The approach has to consider the solid form of the materials and compatibility of any auxiliary used. This

• ; mechanochemistry; multistep; solid-state synthesis; Introduction Mechanochemical methods are emerging as an alternative approach to traditional solvent-based reactions for chemical synthesis. Under mechanochemical conditions reactions are performed between neat reagents and do not require a solvent. Processing

• those that are significantly shorter in reaction time than those conducted in solution. Indeed, there are several examples where reactions are clearly significantly faster under mechanochemical conditions [7][8]. One of several challenges to be overcome for the further development of mechanochemistry as

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

• global warming, it is important to minimize the usage of hazardous chemicals in both academic and industrial research, elimination of waste, and possibly recycle them to obtain better results in greener fashion. The studies under the area of mechanochemistry which cover the grinding chemistry to ball

• (C–X), etc. is documented. Mechanochemical syntheses of heterocyclic rings, multicomponent reactions and organometallic molecules including their catalytic applications are also highlighted. Keywords: ball-milling; green chemistry; mechanochemistry; solid-phase synthesis; solvent-free synthesis

• received the Nobel Prize in 1909, mentioned the term “Mechanochemistry” as, like a branch of physical chemistry, i.e., thermochemistry, photochemistry and electrochemistry [13][14]. He defined the subject as “Mechanochemistry is a branch of chemistry which is concerned with chemical and physio-chemical

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

• mechanochemistry offers significant challenges. For instance, the molecular weight negatively affects the reaction design and is almost one order of magnitude higher here than for common organic molecules. The laborious preparation of the starting CD-tosylate [24][25], and the considerable reactant molecular mass

• . Although it is difficult to reach a compromise between the reaction and side reactions, without a massive energy transfer the derivatizations are rarely successful in solution. By mechanochemistry, the reactivity is mainly affected by the sun wheel speed and the number and size of balls for both nitrogen

• poorly understood aspect of mechanochemistry. Effect of jar size on the reaction time using an equal number (30) of steel balls (ø 1 mm) for the Ts → N3 exchange reaction in glass vials at 550 min−1 sun wheel speed. Effect of ball size on the reaction time to a full conversion of Ts-β-CD: a) reactions

Solvent-free sonochemistry: Sonochemical organic synthesis in the absence of a liquid medium

• Deborah E. Crawford

Beilstein J. Org. Chem. 2017, 13, 1850–1856, doi:10.3762/bjoc.13.179

• recently been recognised for its similarity to mechanochemistry and is now included under the umbrella term of mechanochemistry. Typically, due to the hypothesised cavitation mechanism, a liquid medium is considered as a necessity for a process to take place as a result of ultrasonic irradiation. In view

• . Keywords: mechanochemistry; organic; solvent-free; sonochemistry; synthesis; Introduction Mechanochemistry is typically regarded as the grinding of solid reagents in a ball mill (or mortar and pestle), to instigate and accelerate chemical reactions [1]. In recent years, mechanochemistry has evolved to

• include techniques such as shearing [2], microfluidics [3] and twin screw extrusion [4][5][6]. More recently, sonochemistry has been included under the umbrella term of mechanochemistry [7] as it has demonstrated excellent potential when instigating chemical activity in solutions by applying mechanical

Mechanochemical synthesis of thioureas, ureas and guanidines

• Vjekoslav Štrukil

Beilstein J. Org. Chem. 2017, 13, 1828–1849, doi:10.3762/bjoc.13.178

• , mechanochemistry has been demonstrated as an effective tool in reaction discovery, with emphasis on the reactivity differences in solution and in the solid state. These three classes of organic compounds share some structural features which are reflected in their physical and chemical properties, important for

• application as organocatalysts and sensors. On the other hand, the specific and unique nature of each of these functionalities render (thio)ureas and guanidines as the key constituents of pharmaceuticals and other biologically active compounds. Keywords: guanidines; mechanochemistry; solid state synthesis

• transferred from the solution into the solid state. In a typical solid state organic synthesis, reactants are simply ground together in a mortar using a pestle, where the mechanical force is exerted by a hand (manual grinding) [15]. Whereas mechanochemistry [16], at least on the laboratory scale, is usually

Selective enzymatic esterification of lignin model compounds in the ball mill

• Ulla Weißbach,
• Saumya Dabral,
• Laure Konnert,
• Carsten Bolm and
• José G. Hernández

Beilstein J. Org. Chem. 2017, 13, 1788–1795, doi:10.3762/bjoc.13.173

• the advantages of enzyme catalysis and mechanochemistry. Under the described conditions, the primary aliphatic hydroxy groups present in the substrates were selectively modified by the biocatalyst to afford monoesterified products. Amongst the tested lipases, CALB proved to be the most effective

• biocatalyst for these transformations. Noteworthy, various acyl donors of different chain lengths were tolerated under the mechanochemical conditions. Keywords: ball milling; enzymes; esterification; lignin derivatization; mechanochemistry; Introduction Mechanochemical reactions, particularly those carried

• ), showed the highest selectivity and could also be recycled by centrifugation and reused with little loss in stereoselectivity after four consecutive cycles [10]. Besides the above stated, one additional advantage of mechanochemistry includes the possibility to overcome solubility restrictions in chemical

Mechanochemical N-alkylation of imides

• Anamarija Briš,
• Mateja Đud and
• Davor Margetić

Beilstein J. Org. Chem. 2017, 13, 1745–1752, doi:10.3762/bjoc.13.169

• synthesis of amines by their reaction with 1,2-diaminoethane. Keywords: ball milling; Gabriel reaction; imides; mechanochemistry; N-alkylation; Introduction The development of environmentally friendly organic reactions is a growing area of interest [1]. The reduction of the impact of chemical reactions on

Mechanochemical enzymatic resolution of N-benzylated-β³-amino esters

• Mario Pérez-Venegas,
• Gloria Reyes-Rangel,
• Adrián Neri,
• Jaime Escalante and
• Eusebio Juaristi

Beilstein J. Org. Chem. 2017, 13, 1728–1734, doi:10.3762/bjoc.13.167

• . Universidad 1001, Cuernavaca, Morelos, 62210, Mexico El Colegio Nacional, Luis Gonzáles Obregón 23, Centro Histórico, Ciudad de México, 06020, Mexico 10.3762/bjoc.13.167 Abstract The use of mechanochemistry to carry out enantioselective reactions has been explored in the last ten years with excellent results

• resolution; mechanochemistry; Introduction β-Amino acids are rather interesting molecules that frequently exhibit exceptional biological properties [1][2][3]; for instance, some of them are efficient inhibitors of several enzymes [4][5]. Furthermore, β-amino acid residues can be used to protect peptides and

• in instrumentation for synthetic chemistry, mechanochemistry has proved a rather attractive and useful technique [31][32][33][34][35][36][37]. In particular, it has been demonstrated that mechanochemistry allows for the generation of products through catalysts that can be recovered and reused [38][39

Encaging palladium(0) in layered double hydroxide: A sustainable catalyst for solvent-free and ligand-free Heck reaction in a ball mill

• Wei Shi,
• Jingbo Yu,
• Zhijiang Jiang,
• Qiaoling Shao and
• Weike Su

Beilstein J. Org. Chem. 2017, 13, 1661–1668, doi:10.3762/bjoc.13.160

• catalyst. The results show that the reaction yield kept unchanged when the Pd/MgAl-LDHs loading was reduced to 2.5 mol % (Table 1, entry 9). After getting access to the optimal reactant system, we shifted our focus on the mechanochemistry parameters of mill-ball size and its filling degree. The milling

Mechanochemical borylation of aryldiazonium salts; merging light and ball milling

• José G. Hernández

Beilstein J. Org. Chem. 2017, 13, 1463–1469, doi:10.3762/bjoc.13.144

• –solvent charge-transfer complex formation. Keywords: aryldiazonium salts; borylation; eosin Y; mechanochemistry; photocatalysis; Introduction The use of mechanical force to process materials or to induce chemical transformations is perhaps as old as the history of mankind itself [1]. Similarly, from

• potential of having both activation modes acting simultaneously. In recent years, mechanochemistry, which encompasses the use of mechanical means by milling, grinding, shearing, cavitation or pulling to induce chemical transformations [3] has become fundamental for discovering new chemical reactivity [4][5

• alternative to the standard neat grinding, has become an useful parameter in mechanochemistry to control chemical selectivity and product composition by having catalytic volumes of organic solvent during the milling [24]. Here, a change in the milling approach from neat to LAG was anticipated to have the

Mechanochemistry-assisted synthesis of hierarchical porous carbons applied as supercapacitors

• Desirée Leistenschneider,
• Nicolas Jäckel,
• Felix Hippauf,
• Volker Presser and
• Lars Borchardt

Beilstein J. Org. Chem. 2017, 13, 1332–1341, doi:10.3762/bjoc.13.130

• of synthesis steps and to minimize waste accumulation, at best by avoiding any solvents [7][31]. Lately, mechanochemistry has gained momentum in organic chemistry [32][33][34]. The initiation of chemical reactions by mechanical forces enables organic and inorganic syntheses without the use of any

• for the synthesis of uniform metal oxide nanoparticles to synthesize a titanium(IV) citrate-based polymer [44][45]. The Pechini method is applicable to synthesize templated mesoporous carbons [46][47][48][49], but has never been utilized for a solvent-free and rapid process based on mechanochemistry

Nucleophilic displacement reactions of 5′-derivatised nucleosides in a vibration ball mill

• Olga Eguaogie,
• Patrick F. Conlon,
• Francesco Ravalico,
• Jamie S. T. Sweet,
• Thomas B. Elder,
• Louis P. Conway,
• Marc E. Lennon,
• David R. W. Hodgson and
• Joseph S. Vyle

Beilstein J. Org. Chem. 2017, 13, 87–92, doi:10.3762/bjoc.13.11

• corresponding 5′-selenocyanates in variable yields over the course of between one and eleven hours thereby avoiding the preparation and use of hygroscopic tetrabutylammonium salts. Keywords: ball mill; chalcogen; mechanochemistry; nucleophilic substitution; nucleoside; Introduction Nucleophilic displacement

Poly(ethylene glycol)s as grinding additives in the mechanochemical preparation of highly functionalized 3,5-disubstituted hydantoins

• Andrea Mascitti,
• Massimiliano Lupacchini,
• Ruben Guerra,
• Ilya Taydakov,
• Lucia Tonucci,
• Nicola d’Alessandro,
• Frederic Lamaty,
• Jean Martinez and
• Evelina Colacino

Beilstein J. Org. Chem. 2017, 13, 19–25, doi:10.3762/bjoc.13.3

• agents. In general, cleaner reaction profiles were observed in the presence of PEGs, compared to dry-grinding procedures. Keywords: ball-milling; 1,1’-carbonyldiimidazole (CDI); hydantoins; mechanochemistry; liquid-assisted grinding (LAG); poly(ethylene) glycols (PEGs); Introduction Poly(ethylene

Efficient mechanochemical synthesis of regioselective persubstituted cyclodextrins

• Laszlo Jicsinszky,
• Marina Caporaso,
• Katia Martina,
• Emanuela Calcio Gaudino and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2016, 12, 2364–2371, doi:10.3762/bjoc.12.230

• despite the fact that only traces of incompletely substituted azido-CDs and decomposition products were found in solution and that the reaction mixture composition was similar to the solution composition (entries 14 and 15 in Table 1). In conclusion, it appears that the advantage of mechanochemistry is

Solvent-free, visible-light photocatalytic alcohol oxidations applying an organic photocatalyst

• Martin Obst and
• Burkhard König

Beilstein J. Org. Chem. 2016, 12, 2358–2363, doi:10.3762/bjoc.12.229

• and Nobel Prize laureate 1909, chemistry can be divided into the four sub-disciplines thermochemistry, electrochemistry, photochemistry, and mechanochemistry, depending on the kind of energy involved in a chemical process [1]. Among these, mechanochemistry is nowadays a well-established method for the

• [3]. This approach avoids expensive reagents and harsh reaction conditions, which are improvements compared to conventional processes. Considering that, we envisaged combining photocatalysis with mechanochemistry, thereby making use of the advantages of both disciplines. In such an approach, solid

• substrates would be grinded under visible light irradiation. In contrast to mechanochemistry, the process would be driven by light energy and not by mechanical energy, but profit from the absence of toxic solvents, high concentrations of the substrate, and easy work-up. Furthermore, undesired effects of the

Enabling technologies and green processes in cyclodextrin chemistry

• Giancarlo Cravotto,
• Marina Caporaso,
• Laszlo Jicsinszky and
• Katia Martina

Beilstein J. Org. Chem. 2016, 12, 278–294, doi:10.3762/bjoc.12.30

• in types 2) and 3) can reduce or eliminate the polluting environment. Reactions of type 1) are dominant in CD/BM literature; more than 98% of publications report the complexation of one or more components. Mechanochemistry opened a new synthetic pathway to the preparation of numerous fullerene

Expeditious, mechanochemical synthesis of BODIPY dyes

• Laramie P. Jameson and
• Sergei V. Dzyuba

Beilstein J. Org. Chem. 2013, 9, 786–790, doi:10.3762/bjoc.9.89

• pestle and mortar, with yields that are comparable to those obtained via traditional routes that typically require reaction times of several hours to days. Keywords: BODIPY; condensation; fluorescent dye; mechanochemistry; solvent-free; Introduction BODIPY dyes are fluorescent organic molecules, which

Mechanochemistry assisted asymmetric organocatalysis: A sustainable approach

• Pankaj Chauhan and
• Swapandeep Singh Chimni

Beilstein J. Org. Chem. 2012, 8, 2132–2141, doi:10.3762/bjoc.8.240

• : ball-milling; enantioselective synthesis; mechanochemistry; organocatalysis; solvent-free; Introduction Green chemistry involves innovation in chemical research and engineering that encourages the design of processes to minimize the use and production of hazardous materials and also reduce the use of