Solventless mechanosynthesis of N-protected amino esters

From Synthesis of Amino Acids and Peptides to Enzymatic Catalysis: A Bottom-Up Approach in Mechanochemistry

Recently, chemical reactions induced or facilitated by mechanical energy have gained recognition in diverse areas of chemical synthesis. In particular, mechanosyntheses of amino acids and short peptides, along with their applications in catalysis, have revealed the high degree of stability of peptide bonds in environments of harsh mechanical stress. These observations quickly led to the recent interest in developing mechanochemical enzymatic reactions. Experimentally, manual grinding, ball-milling techniques, and twin-screw extrusion technology have proven valuable to convey mechanical forces into a chemical synthesis. These practices have enabled the establishment of more sustainable alternatives for chemical synthesis by reducing the use of organic solvents and waste production, thereby having a direct impact on the E-factor of the chemical process. In this Minireview, the series of events that allowed the development of mechanochemical enzymatic reactions are described from a bottom-up perspective.

Mechanically induced oxidation of alcohols to aldehydes and ketones in ambient air: Revisiting TEMPO-assisted oxidations

The present work addresses the development of an eco-friendly and cost-efficient protocol for the oxidation of primary and secondary alcohols to the corresponding aldehydes and ketones by mechanical processing under air. Ball milling was shown to promote the quantitative conversion of a broad set of alcohols into carbonyl compounds with no trace of an over-oxidation to carboxylic acids. The mechanochemical reaction exhibited higher yields and rates than the classical, homogeneous, TEMPO-based oxidation.

Mechanochemical synthesis of small organic molecules

With the growing interest in renewable energy and 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 milling, sonication, etc. are certainly of interest to the researchers working on the development of green methodologies. In this review, a collection of examples on recent developments in organic bond formation reactions like carbon–carbon (C–C), carbon–nitrogen (C–N), carbon–oxygen (C–O), carbon–halogen (C–X), etc. is documented. Mechanochemical syntheses of heterocyclic rings, multicomponent reactions and organometallic molecules including their catalytic applications are also highlighted.

Poly(ethylene) glycols and mechanochemistry for the preparation of bioactive 3,5-disubstituted hydantoins

Mechanochemistry was effective for the preparation of 3,5-disubstituted hydantoins from α-amino methyl esters, using either 1,1′-carbonyldiimidazole (CDI) or alkyl isocyanates.

Mechanochemical reactions studied by in situ Raman spectroscopy: base catalysis in liquid-assisted grinding

Monitoring byin situRaman spectroscopy of a mechanochemical substitution reaction on a carbonyl group reveals base catalysis akin to catalysis in solution.