L–Cysteine‐Catalysed Hydration of Activated Alkynes

Abstract Hydration reactions consist of the introduction of a molecule of water into a chemical compound and are particularly useful to transform alkynes into carbonyls, which are strategic intermediates in the synthesis of a plethora of compounds. Herein we demonstrate that L–cysteine can catalyse the hydration of activated alkynes in a very effective and fully regioselective manner to access important building blocks in synthetic chemistry such as β‐ketosulfones, amides and esters, in aqueous media. The mild reaction conditions facilitated the integration with enzyme catalysis to access chiral β‐hydroxy sulfones from the corresponding alkynes in a one‐pot cascade process in good yields and excellent enantiomeric ratios. These findings pave the way towards establishing a general method for metal‐free, cost‐effective, and more sustainable alkyne hydration processes.