Solvent-free synthesis of thioglycosides by ball milling

Patil, Premanand Ramrao; Kartha, K. P. Ravindranathan

doi:10.1039/b904454j

Cited by 47 publications

(6 citation statements)

References 32 publications

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“…Although a large number of organic reactions have been performed in PBMs, the influence of the beaker volume has not been investigated. , However, the geometry of the milling beakers influences the energy input as shown by Mio and co-workers in milling experiments of gibbsite powder . To investigate the influence of the beaker size and geometry on the Knoevenagel condensation, we performed the model reaction in five different milling beakers in which the volume ( V MV ), inner diameter ( d MV ), and height ( h MV ) of the beaker were varied.…”

Section: Resultsmentioning

confidence: 99%

Effect of Reaction Parameters on the Synthesis of 5-Arylidene Barbituric Acid Derivatives in Ball Mills

Schmidt

Burmeister

Baláž

et al. 2015

Org. Process Res. Dev.

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The influence of crucial reaction parameters on Knoevenagel condensation in planetary ball mills was investigated. Rotation frequency (ν rot ), milling ball diameter (d MB ), milling ball filling degree (Φ MB ), and beaker size had obvious influences on yield. It was found that higher ν rot , lower d MB , milling beakers with larger diameter, and a Φ MB of ∼0.3 are advantageous for the reaction. Furthermore, the influence of the type of mill was investigated, including reactions performed in different planetary and mixer ball mills, in a stirred media mill, and with a mortar mill. Comparisons with the other solvent-free synthetic routes showed that ball milling is an effective way of performing the reaction with low energy intensity. ■ INTRODUCTIONThe use of mechanical stress for the accomplishment of mechanochemical reactions is now an established field of research represented by a huge number of reactions in different fields of organic, inorganic, and organometallic chemistry and materials science. 1 In all cases, mechanical stress is provided to the reactants, whereby the energy input can be realized in different ways. The easiest but imprecise way is to use a mortar and pestle. 2 Results that are more reliable can be obtained with different types of ball mills, such as planetary (PBMs) or mixer ball mills (MBMs). The results of organic reactions in ball mills are subject to several influencing parameters, especially the influence of rotation frequency (ν rot ), milling time (t), and number of milling balls (n MB ). 3 Although a large number of synthesis protocols have been published, parameters such as the milling ball diameter (d MB ) 3c,d,4 and beaker size 5 have received less attention. Furthermore, comparative studies on reactions in different types of mills are rare. 2,6 However, the kind of mill utilized can strongly influence the outcome of a reaction. For example, Schneider et al. investigated the Suzuki−Miyaura reaction in two types of PBMs and one MBM. 2 The reaction proceeded well in the PBMs at 300 min −1 , whereas in the MBM at the same frequency only low yields were observed. Wang and co-workers investigated pinacol couplings in an MBM and a mortar mill (MM). 6a Although mechanical energy is supplied in both mill types, higher yields of the pinacol coupling product were obtained in an MM.We have recently investigated the influence of several reaction parameters on the yield of a Knoevenagel condensation of vanillin (1a) and barbituric acid (2a) (Scheme 1) in a planetary ball mill aiming to close this knowledge gap, 5 including questions regarding the influence of beaker size, geometry, and the way the mechanical energy is provided. To this end, Knoevenagel condensation was performed using various tools for allocating mechanical stress.To investigate the influence of different milling and grinding apparatuses, three different types of PBMs, an MBM, a stirred media mill (SMM), an MM, and a mortar and pestle were used. The main differences between the PBMs are the diameter of the main disc (d MD ),...

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Section: Resultsmentioning

confidence: 99%

Effect of Reaction Parameters on the Synthesis of 5-Arylidene Barbituric Acid Derivatives in Ball Mills

Schmidt

Burmeister

Baláž

et al. 2015

Org. Process Res. Dev.

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“…Remarkably, S N 2 ball-milling chemistry on nucleoside substrates has not, to the authors’ knowledge, been demonstrated, despite reports of similar chemistry on glycoside derivatives [16,23] and α-amino acid analogues [24]. …”

Section: Introductionmentioning

confidence: 98%

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

Eguaogie¹,

Conlon²,

Ravalico³

et al. 2017

Beilstein J. Org. Chem.

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Vibration ball-milling in a zirconia-lined vessel afforded clean and quantitative nucleophilic displacement reactions between 4-methoxybenzylthiolate salts and nucleoside 5′-halides or 5′-tosylates in five to 60 minutes. Under these conditions, commonly-encountered nucleoside cyclisation byproducts (especially of purine nucleosides) were not observed. Liquid-assisted grinding of the same 5'-iodide and 5′-tosylate substrates with potassium selenocyanate in the presence of DMF produced the 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.

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“…The method was also extended to the synthesis of thioarylglycosides (Scheme 13, path b), useful donors for oligosaccharide synthesis. Alternative routes to thioglycosides, based on substitution reactions on glycosyl halides with thiourea or potassium thioacetate as the nucleophiles, also proved viable under ball milling conditions [71]. It is worth pointing out in all these examples the lack of 1,2-orthoester coupling products, typically obtained as side-products when glycosidations with 2-O-acylated donors are conducted in solution under basic conditions.…”

Section: Solvent-free Glycosidationsmentioning

confidence: 99%

Solvent-Free Approaches in Carbohydrate Synthetic Chemistry: Role of Catalysis in Reactivity and Selectivity

et al. 2020

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Owing to their abundance in biomass and availability at a low cost, carbohydrates are very useful precursors for products of interest in a broad range of scientific applications. For example, they can be either converted into basic chemicals or used as chiral precursors for the synthesis of potentially bioactive molecules, even including nonsaccharide targets; in addition, there is also a broad interest toward the potential of synthetic sugar-containing structures in the field of functional materials. Synthetic elaboration of carbohydrates, in both the selective modification of functional groups and the assembly of oligomeric structures, is not trivial and often entails experimentally demanding approaches practiced by specialized groups. Over the last years, a large number of solvent-free synthetic methods have appeared in the literature, often being endowed with several advantages such as greenness, experimental simplicity, and a larger scope than analogous reactions in solution. Most of these methods are catalytically promoted, and the catalyst often plays a key role in the selectivity associated with the process. This review aims to describe the significant recent contributions in the solvent-free synthetic chemistry of carbohydrates, devoting a special critical focus on both the mechanistic role of the catalysts employed and the differences evidenced so far with corresponding methods in solution.

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Solvent-free synthesis of thioglycosides by ball milling

Cited by 47 publications

References 32 publications

Effect of Reaction Parameters on the Synthesis of 5-Arylidene Barbituric Acid Derivatives in Ball Mills

Effect of Reaction Parameters on the Synthesis of 5-Arylidene Barbituric Acid Derivatives in Ball Mills

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

Solvent-Free Approaches in Carbohydrate Synthetic Chemistry: Role of Catalysis in Reactivity and Selectivity

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