多羰基甾酮的选择性还原反应研究

在不同金属离子存在下,多羰基甾酮的甾核及支链上都发生了羰基与硼氢化钠的还原反应,得到具有不同的区域选择性和立体选择性的还原产物.     

Asymmetric reduction of acetophenone and propiophenone by NaAl(IPTOLate)H2 combined with enantiomeric enrichment of the reaction product as an inclusion complex with IPTOL

An improved procedure was developed for asymmetric reduction of acetophenone and propiophenone by the chiral reagent NaAl(IPTOLate)H₂. This procedure is based on isolation of the chiral alcohol that formed as a crystalline host—guest complex with the IPTOL ligand. The enantiomeric enrichment of the product was as high as 97% ee. The ability of IPTOL and its analogs to form host—guest complexes with a number of ether-type solvents, 1-phenylethanol, and 1-phenylpropan-1-ol as well as thermal stabilities of IPTOL-containing complexes with these alcohols were studied.     

Effect of 4f-shell excitation of Eu(fod)3 on its complex formation with alicyclic ketones

The complex formation of alicyclic ketones, viz., camphor, cyclohexanone, menthone, and cytisine, with the Eu(fod)₃ chelate (fod is 7,7-dimethyl-1,1,1,2,2,3,3-heptafluorooctane-4,5-dione) in the ground and excited states was studied by chemiluminescence and kinetic luminescence spectroscopy, respectively. The stability constants and thermodynamic parameters of complex formation were determined. An increase in the stability of the electron-excited complexes [Eu(fod)₃*·Ketone] is explained by the enhancement of the acceptor ability of the Eu³⁺ chelate due to an increase in the fraction of the covalent component caused by the involvement of 4f-orbitals. The results obtained give direct evidence for the effect of the 4f-shell excitation of Eu(fod)₃ on complex formation due to the involvement of f-electrons in the chemical bonds.     

KF/clinoptilolite nanoparticles as a novel catalyst for the green synthesis of chromens using three component reactions of 4‐hydroxycoumarins: Study of antioxidant activity

In this research, the green synthesis of chromen derivatives in good yields is described via three‐component reactions of 4‐hydroxycumarine, aldehydes or ketones, and methyl ketones in the presence of KF/clinoptilolite nanoparticles (KF/CP‐NPs) under solvent‐free conditions at 50°C in low time. The present methodology suggests some advantages such as low reaction time, easy and simple procedure, green method, inexpensive catalyst, high yield of product, and existence of different substrates for performing these reactions. In addition, it should be mentioned that antioxidant activity was studied for some prepared compounds, such as 4a–4d, by DPPH radical trapping and reducing potential tests of ferric ion and then comparing results with TBHQ and BHT as synthetic antioxidants. In this study, compounds 4c was shown to have moderate DPPH radical trapping, and compounds 4b and 4d displayed good reducing power of ferric ion.     

Synthesis of alkyl (α-phenylthioalkenyl) ketones containing a (Z)-trisubstituted olefinic fragment

Warren"s method, which has been proposed for the synthesis of -phenylthiodialkyl ketones, appeared to be inefficient for the preparation of their alkenyl alkyl analogs. The latter were prepared in good yields by alkenylation of alkyl phenylthiomethyl ketones with alkenyl bromides.     

Enzymatic synthesis of optically active α-chloro-δ-hydroxy-β-ketoalkanephosphonates and reactions thereof

A novel and enzymatic approach to α-chloro-δ-hydroxy-β-ketoalkanephosphonates was developed via enantioselective CALB-catalyzed acetylation and CRL-catalyzed hydrolysis. The resultant optically active compounds provide, via Horner-Wadsworth-Emmons (HWE) reaction, chiral α,β-unsaturated ketones that are building block with potential application in organic synthesis.     

Direct Asymmetric α-Selective Mannich Reaction of β,γ-Unsaturated Ketones with Cyclic α-Imino Ester: Divergent Synthesis of Cyclocanaline and Tetrahydro Pyridazinone Derivatives

The first regio-, diastereo-, and enantioselective direct Mannich reaction of β,γ,-unsaturated ketones with benzoxazinone cyclic imines was enabled by Lewis acid/Brønsted base cooperative catalysis. The dinuclear zinc complex catalyzed the reaction of a broad range of β,γ-unsaturated ketones to proceed at the α-site exclusively, leading to corresponding adducts with two consecutive tertiary carbon stereocenters in diastereomeric ratios of up to >20:1 and enantioselectivities generally in the 90–99 % ee range. These products were used as general intermediates in the synthesis of multisubstituted cyclocanalines, tetrahydro pyridazinones, and 4H-furo[2,3-b][1,4]benzoxazine derivatives.     

Synthesis and thermal decomposition of 3-aroyl-4-aryl-2-pyrazolines

Summary 3-Aroyl-4-aryl-2-pyrazolines (21–40) have been synthesized by the reaction of ,-unsaturated ketones (1–20) with diazomethane. These 2-pyrazolines gave -methyl-,-unsaturated ketones (41–46) on thermal denitrogenation.Dedicated to Prof. Dr.F. Sauter on the occasion of his 65^th birthday     

Zinc mediated reductive dimerization and cyclization of α,β-unsaturated ketones in the presence of a catalytic amount of mercury(II) chloride

The zinc mediated reductive dimerization and cyclization of α,β-unsaturated ketones gives functionalized cyclopentanols in good yield in the presence of a catalytic amount of mercury(II) chloride in N,N-dimethylformamide as solvent at room temperature. The reaction is regio- and stereo-selective producing 3,4-trans-diarylcyclopentanols selectively.