Green chemistry asymmetric hydrogenation

Several approaches have been described for the preparation of optically active sulfoxides [5-7]. The three main routes to obtain these compounds are as follows (i) the asymmetric sulfoxidation of prochiral sulfides, (ii) nucleophilic substitution using a chiral sulfur precursor, and (iii) the kinetic resolution of racemic sulfoxides. The first of tiiese methods involves the use of various oxidants and catalysts and has been the most extensively employed. There are many examples in the scientific literature and reviews are available on this approach. In recent years, much attention has been focused on the synthesis of organic sulfoxides by emplo5dng conditions compatible with the green chemistry procedures [8-10]. For this reason, mild oxidants such as molecular oxygen or hydrogen peroxide are considered in combination with novel catalysts in order to develop a mild and environmentally friendly process. 

Reproduced from Wang Y-F. Chen R-X, Wang K. Zhang B-B. Li Z-B, Xu D-Q. Fast, solvent-free and hydrogen-bonding-mediated asymmetric Michael addition In a ball mill. Green Chem 2012 14 893-5. With permissioh from the Royal Society of Chemistry. 

Fteproduced Horn Jorres M. Mersmann S, Raabe G, Bokn C. Organocatalytic solvent-free hydrogen bonding mediated asymmetric Michael additions under ball milling conditions. Green Chem 2013 15 612-6. With permission from the Ftoyal Society of Chemistry. 

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