17218-62-1Relevant academic research and scientific papers
One-Step Chemo-, Regio- and Stereoselective Reduction of Ketosteroids to Hydroxysteroids over Zr-Containing MOF-808 Metal-Organic Frameworks
Llabrés i Xamena, F. X.,Mautschke, H.-H.
, p. 10766 - 10775 (2021)
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 17α-hydroxy derivatives in one step, whereas most chemical and biological transformations produce the 17β-OH compounds, or they require several additional steps to convert 17β-OH into 17α-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.
A GENERAL METHOD FOR THE SELECTIVE REDUCTION OF KETONES IN THE PRESENCE OF ENONES.
Ward, Dale E.,Rhee, Chung K.,Zoghaib, Wajdi M.
, p. 517 - 520 (2007/10/02)
Ketones can be reduced in the presence of conjugated enones by sodium borohydride in 50percent methanol in dichloromethane at -78 deg C.The selectivity is generally excellent.In favorable cases the reaction can be carried out at room temperature in dichloromethane with acetic acid as catalyst.
METAL-ASSISTED REACTIONS-12. UNUSUAL SELECTIVITY IN THE REDUCTION OF KETONES WITH ZINC OR CADMIUM BIS-TETRAHYDROBORATE/DIMETHYLFORMAMIDE COMPLEX
Hussey, Brendan J.,Johnstone, Robert A. W.,Boehm, Peter,Entwistle, Ian D.
, p. 3769 - 3774 (2007/10/02)
Zinc bis-tetrahydroborate forms a solid complex with dimethylformamide (DMF) of composition, Zn(BH4)2*1.5DMF.Unlike zinc bis-tetrahydroborate itself, the complex with DMF can be stored as a solid at room temperature.Ketones and aldehydes are reduced to the corresponding alcohols by the complex but the mechanism of reduction appears to be different from that using zinc bis-tetrahydroborate itself and from other tetrahydroborates in that only one hydride equivalent from each BH4- unit is utilized and not four.Further, although saturated aliphatic ketones are reduced rapidly to alcohols, aromatic ketones react much more slowly and α,β-unsaturated ketones react very slowly so that the complex appears to have selective reducing potential with regard to different classes of ketones.It is also apparent that the zinc bis-tetrahydroborate/DMF complex reduces sterically hindered saturated ketones much more slowly than it does unhindered ketones.An analogous cadmium bis-tetrahydroborate/DMF complex can be prepared in solution and reacts with ketones similarly to the zinc complex.
SELECTIVITE DE LA REDUCTION D'α-ENONES POLYCYCLIQUES PAR LES BOROHYDRURES: EFFET DE L'ADDITION DE TETRAMETHYL-ETHYLENEDIAMINE AU BOROHYDRURE DE TETRABUTYLAMMONIUM
D'incan, E.,Loupy, A.,Maia, A.,Seyden-Penne, J.,Viout, P.
, p. 2923 - 2927 (2007/10/02)
Δ1,9octalone, Δ1,9-10-methyl octalone and testosterone were reduced by NBu4BH4, alone or in the presence of tetramethylethylenediamine (TMEDA), in THF and in toluene.With TMEDA, the first step of the reduction is the regioselective 1,4 attack by BH4(1-) which leads either to the saturated ketones or to the corresponding saturated alcohols.The results observed under different conditions were interpreted by the intervention of various reductive species: diborane, enoxyborohydrides in the absence of TMEDA, amine-borane in its presence.
