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排序方式: 共有281条查询结果,搜索用时 109 毫秒
1.
Xueting Zhou Qingqin Huang Jiami Guo Dr. Lei Dai Prof. Dr. Yixin Lu 《Angewandte Chemie (International ed. in English)》2023,62(45):e202310078
Chiral α,α-diaryl ketones are structural motifs commonly present in bioactive molecules, and they are also valuable building blocks in synthetic organic chemistry. However, catalytic asymmetric synthesis of α,α-diaryl ketones bearing a tertiary stereogenic center remains largely unsolved. Herein, we report a catalytic de novo enantioselective synthesis of α,α-diaryl ketones from simple alkynes via chiral phosphoric acid (CPA) catalysis. A broad range of enolizable α,α-diaryl ketones are prepared in good yields and with excellent enantioselectivities. The described protocol also serves as an efficient deuteration method for the preparation of enantiomerically enriched deuterated α,α-diaryl ketones. Using the methodology reported, bioactive molecules, including one of the best-selling anti-breast cancer drugs, tamoxifen, are readily synthesized. 相似文献
2.
The coupling reactions of simple methyl ketones with o-bromoacetophenones and subsquential cyclization reactions were realized to produce a range of 1-naphthols. These cascade reactions were initiated by a rare Cu-catalyzed arylation reaction of methyl ketones with aromatic bromides. 相似文献
3.
《Comptes Rendus Chimie》2014,17(3):293-300
Supercritical carbon dioxide (scCO2) can be used as a “green” selective solvent for extractions of wheat straw waxes. For the first time, the crude extraction yields of wheat straw waxes and the yields of a single high value group of components (wax esters) using various scCO2 conditions (305.15 to 373.15 K and 7.5 to 40 MPa) have been modelled using the Chrastil equation (Chrastil, 1982). The model accurately predicts both the crude yield and percentage of valuable wax esters within the extracts enabling maximum extraction efficiency. The key compounds within the waxes (fatty acids, sterols, fatty alcohols, wax esters, β-diketones and alkanes) have been identified and quantified. This study highlighted that, 14,16 hentriacontanedione was extracted at critical temperature and pressure in concentrations of 1000 μg.g−1 straw. This molecule could demonstrate significant potential as a natural chelate for metal recovery and also in the formation of super-hydrophobic coatings. 相似文献
4.
《Tetrahedron》2014,70(52):9814-9818
New process that can selectively prepare α,α-dichloro ketones from various ketones with 1,3-dichloro-5,5-dimethylhydantoin (DCDMH) using ammonium chloride as a catalyst is reported. The effects of ammonium salts, solvents, DCDMH, and reaction temperature were investigated. Under the optimal condition, most of α,α-dichlorinated products were selectively obtained in 86–98% yield. 相似文献
5.
2-Substituted-2,3-dihydro-4(1H)-quinazolinones were synthesized in high yield by condensation of 2-anthranilamide with aromatic aldehydes or ketones in refluxing water without catalyst.This protocol has advantages of high yield,simple work-up and environmental friendly procedure. 相似文献
6.
4-Aminoperoxybenzoic acid supported on silica gel was found to be a versatile and efficient oxidant for the oxidation of ketones to esters. 相似文献
7.
Atul C. Chaskar Arun A. Yadav Bhushan P. Langi Anita Murugappan Chetan Shah 《合成通讯》2013,43(19):2850-2856
Simple, efficient, and mild method for α-thiocyanation of ketones in presence of heteropolyacid has been developed. This methodology offered α-oxothiocyanates in good to excellent yields at room temperature in a highly selective manner. The catalyst could be efficiently recovered from the reaction and reused. 相似文献
8.
Issa Yavari Mohammad Anary-Abbasinejad Abdolali Alizadeh Azizollah Habibi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2523-2527
The reactive 1:1 intermediate produced in the reaction between triphenylphosphine and alkyl propiolates or ethynyl phenyl ketone was trapped by isopropylidene Meldrum's acid (5-isopropylidene-2,2-dimethyl-1,3-dioxane-4,6-dione) to produce alkyl 3-(isopropylidenemalonate-5-yl-5-ylid)-3-methyl-2-triphenylphosphoniomethylidene-butanoates or 3-(isopropylidenemalonate-5-yl-5-ylid)-3-methyl-2-triphenylphosphoniomethylidene-butanone in 75-86% yield. These 1,5-diionic phosphorus betaines exist as (Z) geometrical isomer in CDCl 3 solution. 相似文献
9.
M. Sreenivasulu K. Arun KumarK. Sateesh Reddy K. Siva KumarP. Rajender Kumar K.B. ChandrasekharManojit Pal 《Tetrahedron letters》2011,52(6):727-732
A rapid, economic, and high yielding methodology has been developed for hydroacylation/reduction of activated ketones by using 1,3-bis(2,4,6-trimethylphenyl)imidazolium chloride as a catalyst in combination with triethylamine. The reaction proceeded at an ambient temperature via generating N-heterocyclic carbene in situ that interacted with the (hetero)aryl aldehyde employed. While the reduction of ketones takes place in MeOH, the hydroacylation process was found to be effective in THF for both electron rich and deficient aldehydes. 相似文献
10.
A new apparatus based on a synthetic method was developed for phase equilibrium measurements. The characteristic features of the apparatus are its light weight (ca. 288 g), variable-volume with a free piston, position sensing device for the piston, precise pressure and temperature control, and a window for visual observation. The inner volume of the cell can vary from 2.5 to 8.8 cm3. The cell was constructed from titanium so that the composition of the sample can be determined by direct weighing of the cell. The apparatus was designed for temperatures up to 473 K and pressures up to 25 MPa. 相似文献