Cationic (eta(6)-arene)tricarbonylmanganese linked to ferrocene complexes

Palladium-catalyzed Sonogashira coupling reactions of the neutral [eta(5)(1-5)-(1-chloro-4-methoxycyclohexa-2,4-dienyl)]tricarbonylmangane se(l) (2) and 2-bromo-5-{[eta(5)(1-5)-(4-methoxycyclohexa-2,4-dienylltricarbonylmangan ese(I)}thiophene (13) with the ethynylferrocene derivative 5 give the dinuclear complexes 1-(ferrocenylethynyl)[eta(5)(1-5)-(4-methoxycyclohexa2,4-dienyl)]tricarb onylmanganese(I) (6) and 2-(ferrocenylethynyl)-5-[eta(5)(1-5)-(4-methoxycyclohexa-2,4-dienyl)tric arbonylmanganese]thiophene (10). Similarly, condensation of 2 with 2-(ferrocenylethynyl)-5-ethynylthiophene (18) affords the dinuclear complex 19. These complexes are valuable precursors, upon hydride abstraction, of the corresponding eta(6)-arene cations 7, 11, and 20. The structure of one of them, 1-(ferrocenylethynyl)[eta(6)(1-6)-(4-methoxybenzene)]tricarbonylmanganes e(I) tetrafluoroborate (7), has been investigated by X-ray diffraction

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

Cationic (eta(6)-arene)tricarbonylmanganese linked to neutral (eta(6)-arene)tricarbonylchromium complexes

Palladium-catalyzed Sonogashira coupling reactions of the neutral [eta(5)(1-5)-1-ethynyl-4-methoxycyclohexa-2,4-dienyl]tricarbonylmanganes e(I) (4) and (eta(6)-chlorobenzene)tricarbonylchromium (5) yields the dinuclear 1-[eta(6)-phenylethynyl]tricarbonylchromium-[eta(5)(1-5)-methoxycyclohex a-2,4-dienyl]tricarbonylmanganese complex 6, which upon hydride abstraction affords the corresponding dinuclear diphenylacetylene eta(6)-Mn/eta(6)-Cr complex 7. This study has been extended to the case of dinuclear eta(6)-Mn/eta(6)-Cr linked to different spacers comprising a thiophene, a triple bond, or a combination of them