One‐Step Chemo‐, Regio‐ and Stereoselective Reduction of Ketosteroids to Hydroxysteroids over Zr‐Containing MOF‐808 Metal‐Organic Frameworks

[EN] Zr-containing MOF-808 is a very promising heterogeneous catalyst for the selective reduction of ketosteroids to the corresponding hydroxysteroids through a Meerwein-Ponndorf-Verley (MPV) reaction. Interestingly, the process leads to the diastereoselective synthesis of elusive 17 alpha-hydroxy derivatives in one step, whereas most chemical and biological transformations produce the 17 beta-OH compounds, or they require several additional steps to convert 17 beta-OH into 17 alpha-OH by inverting the configuration of the 17 center. Moreover, MOF-808 is found to be stable and reusable; it is also chemoselective (only keto groups are reduced, even in the presence of other reducible groups such as C=C bonds) and regioselective (in 3,17-diketosteroids only the keto group in position 17 is reduced, while the 3-keto group remains almost intact). The kinetic rate constant and thermodynamic parameters of estrone reduction to estradiol have been obtained by a detailed temperature-dependent kinetic analysis. The results evidence a major contribution of the entropic term, thus suggesting that the diastereoselectivity of the process is controlled by the confinement of the reaction inside the MOF cavities, where the Zr4+ active sites are located.Financial support by the Spanish Government is acknowledged through projects MAT2017-82288-C2-1-P and the Severo Ochoa program (SEV-2016-0683). The Microscopy Service of the Universitat Politecnica de Valencia is gratefully acknowledged for the electron microscopy images.Mautschke, H.; Llabrés I Xamena, FX. (2021). One-Step Chemo-, Regio- and Stereoselective Reduction of Ketosteroids to Hydroxysteroids over Zr-Containing MOF-808 Metal-Organic Frameworks. Chemistry - A European Journal. 27(41):10766-10775. https://doi.org/10.1002/chem.2021009671076610775274

Norias, boreholes and the role of the state during the groundwater ‘silent revolution’ in La Mancha, Spain

The ‘silent revolution’ is a phenomenon describing the individualistic behaviour of farmers in the adoption of intensive groundwater abstraction technologies, which in some cases has led to groundwater over-abstraction and environmental degradation in semiarid areas such as La Mancha, Spain. However, a lacuna exists as to the extent to which state politics have affected the development of groundwater abstraction technologies in Spain. With new quantitative and qualitative data from the irrigation community of Manzanares and public irrigation and colonisation plans, this report studies the adoption of groundwater abstraction technology and investigates the historical role of the state in the development of modern groundwater-fed irrigation socio-ecologies in the semiarid area of La Mancha in Spain