The worldwide undisputable and unattainable chemist is nature, using water as a solvent of choice in biosynthesis. Water as a solvent not only indicates "green chemistry" but is also inevitable in biochemical reactions as well as syntheses of several pharmaceutical products. In the last few decades, several organic reactions were successfully carried out under aqueous conditions, a powerful and attractive tool in organic synthesis metathesis reaction. This review summarises advances made in metathesis reaction in aqueous media. Two main strategies can be distinguished: the design of water soluble catalysts to obtain homogeneous conditions and using commercially available catalysts to utilize the advantages of heterogeneous conditions. Jasmine Tomasek Jasmine Tomasek studied chemistry at the Friedrich-Alexander University (FAU) of Erlangen-Nuremberg and obtained an M.Sc. in Chemistry in 2011. After this, she joined the research group of J. Schatz and is perusing her Ph.D. research related to the application of supramolecular chemistry in aqueous olefin metathesis reactions. Jürgen Schatz In 1994 Jürgen Schatz completed his Ph.D. in Organic Chemistry under the guidance of Jürgen Sauer at the University of Regensburg. After a postdoctoral stay with C. W. Rees, CBE FRS, at the Imperial College, London, he returned to Germany to start his independent career at the University of Ulm. After one semester at LMU Munich 2007, he moved to his current position at the Friedrich-Alexander University (FAU) of Erlangen-Nuremberg. His research is focused on supramolecular chemistry and its use in catalytic processes with a focus on water as a solvent.

A range of water-immiscible commercially available Grubbs-type precatalysts can be used in ring-closing olefin metathesis reaction in high yields. The synthetic transformation is possible in pure water under ambient conditions. Sulfocalixarenes can help to boost the reactivity of the metathesis reaction by catalyst activation, improved mass transfer, and solubility of reactants in the aqueous reaction media. Additionally, the use of supramolecular additives allows lower catalyst loadings, but still high activity in pure water under aerobic conditions.

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