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1.
Treatment of aromatic 1 , 2-diketones or aromatic a-hydroxy ketones with an activated low-valent titanium reagent, prepared by reduction of TiCl3·1/3AlCl3 with a Zn-Cu reagent, gave an intermolecular coupling reaction leading to the (Z)-1, 2.3.4-tetraaryl-2-butenes. Apossible coupling reaction process was proposed for the aromatic a-hydroxy ketones. 相似文献
2.
Sodium borohydride reduction of saturated aliphatic and aromatic aldehydes and ketones in ethyl acetate at reflux is a facile route for one-pot preparation of acetates from such carbonyl precursors. 相似文献
3.
Harley Green Dr. Stephen P. Argent Prof. Hon Wai Lam 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(19):5897-5900
Domino reactions involving nickel-catalyzed additions of (hetero)arylboronic acids to alkynes, followed by cyclization of the alkenylnickel intermediates onto tethered acyclic ketones to give chiral tertiary-alcohol-containing products in high enantioselectivities, are described. The reversible E/Z isomerization of the alkenylnickel intermediates enables overall anti-arylmetallative cyclization to occur. The ring system of the products are substructures of certain diarylindolizidine alkaloids. 相似文献
4.
Acid catalysed dehydration of the diols 5 , derived from the cyclohexenone 3 affords mixtures of 8 and 11 . The product ratio 8/11 , although strongly dependent on both the reaction conditions and the substituent R, is independent of the diol configuration; this indicates a cationic intermediate 6 . Conditions were found, which allow the sequence A → B → C → D (Scheme 2) to be applied to the syntheses of the enones 8, 21 and 25 in fair to good yields from the corresponding cyclohexenones 3, 18 and 22 . 相似文献
5.
Dr. Xi-Jia Liu Shicheng Jin Wen-Yun Zhang Qiang-Qiang Liu Prof. Dr. Chao Zheng Prof. Dr. Shu-Li You 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(5):2055-2059
The stereodivergent iridium-catalyzed allylic alkylation and fluorination of acyclic ketones is described. α-Pyridyl-α-fluoroketones with vicinal tertiary and quaternary stereocenters were obtained in moderate to excellent yields and stereoselectivities. Distinct from known stereodivergent synthesis, for which two different chiral catalysts are required in general, herein we report a sequence-dependent stereodivergent synthesis. With only a single chiral Ir catalyst, all four possible stereoisomers of the products were prepared from the same starting materials by simply adjusting the sequence of asymmetric allylic alkylation and fluorination and varying the absolute configuration of the Ir catalyst. 相似文献
6.
Julius R. Reyes Prof. Dr. Viresh H. Rawal 《Angewandte Chemie (International ed. in English)》2016,55(9):3077-3080
A method is presented for the direct transformation of a ketone to the corresponding reduced alkyl chloride or bromide. The process involves the reaction of a ketone trityl hydrazone with tBuOCl to give a diazene which readily collapses to the α‐chlorocarbinyl radical, reduction of which by a hydrogen atom source gives the alkyl chloride product. The use of N‐bromosuccinimide provides the corresponding alkyl bromide. This unique transformation provides a reductive halogenation that complements Barton's redox‐neutral vinyl halide synthesis. 相似文献
7.
低价钛引起的邻硝基苯甲酰胺与酮的还原成环反应 总被引:2,自引:1,他引:1
报道了TiCl4-Sm体系引起的邻硝基苯甲酰胺与酮的反应.研究发现,邻硝基苯甲酰胺与酮还原成环生成1,2-二氢喹唑啉-4(3H)-酮.产物的结构通过元素分析、IR、1HNMR谱和单晶X射线衍射法确定. 相似文献
8.
A short and facile synthesis of a series of 1,2-dihydroquiazolin-4(3H)-ones was accomplished in good yields via novel reductive cyclization of o-nitrobenzamides with ketones promoted by TiCI4/Zn system. The structure was established on the basis of elemental analysis, IR,^1H NMR and confirmed by a single-crystal X-ray diffraction analysis. This method has the advantages of easily accessible starting materials, convenient manipulation and moderate to high yields. 相似文献
9.
10.
Iuliia Polishchuk Dr. Jan Sklyaruk Dr. Yury Lebedev Prof. Dr. Magnus Rueping 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(19):5919-5922
Half-sandwich iridium complexes bearing bidentate urea-phosphorus ligands were found to catalyze the direct reductive amination of aromatic and aliphatic ketones under mild conditions at 0.5 mol % loading with high selectivity towards primary amines. One of the complexes was found to be active in both the Leuckart–Wallach (NH4CO2H) type reaction as well as in the hydrogenative (H2/NH4AcO) reductive amination. The protocol with ammonium formate does not require an inert atmosphere, dry solvents, as well as additives and in contrast to previous reports takes place in hexafluoroisopropanol (HFIP) instead of methanol. Applying NH4CO2D or D2 resulted in a high degree of deuterium incorporation into the primary amine α-position. 相似文献
11.
Xi‐Jia Liu Shicheng Jin Wen‐Yun Zhang Qiang‐Qiang Liu Chao Zheng Shu‐Li You 《Angewandte Chemie (International ed. in English)》2020,59(5):2039-2043
The stereodivergent iridium‐catalyzed allylic alkylation and fluorination of acyclic ketones is described. α‐Pyridyl‐α‐fluoroketones with vicinal tertiary and quaternary stereocenters were obtained in moderate to excellent yields and stereoselectivities. Distinct from known stereodivergent synthesis, for which two different chiral catalysts are required in general, herein we report a sequence‐dependent stereodivergent synthesis. With only a single chiral Ir catalyst, all four possible stereoisomers of the products were prepared from the same starting materials by simply adjusting the sequence of asymmetric allylic alkylation and fluorination and varying the absolute configuration of the Ir catalyst. 相似文献
12.
Jun He Yuhang Xue Bo Han Chunzhu Zhang Dr. You Wang Prof. Shaolin Zhu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(6):2348-2352
Starting from diverse alkene-tethered aryl iodides and O-benzoyl-hydroxylamines, the enantioselective reductive cross-electrophilic 1,2-carboamination of unactivated alkenes was achieved using a chiral pyrox/nickel complex as the catalyst. This mild, modular, and practical protocol provides rapid access to a variety of β-chiral amines with an enantioenriched aryl-substituted quaternary carbon center in good yields and with excellent enantioselectivities. This process reveals a complementary regioselectivity when compared to Pd and Cu catalysis. 相似文献
13.
Andrey V. Protchenko Petra Vasko Dinh Cao Huan Do Jamie Hicks M. ngeles Fuentes Cameron Jones Simon Aldridge 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(6):1822-1826
Reactions of a boryl‐substituted acyclic silylene with carbon dioxide and monoxide are reported. The former proceeds through oxygen atom abstraction, generating CO (with rearrangement of the putative silanone product through silyl‐group transfer). The latter is characterized by reductive coupling of CO to give an ethynediolate fragment, which undergoes formal insertion into the Si?B bond. The net conversion of carbon dioxide with two equivalents of silylene offers a route for the three‐electron reduction of CO2 to [C2O2]2?. 相似文献
14.
An overview of studies on hydrogenative reductive aldol addition is presented. By simply hydrogenating enones in the presence of aldehydes at ambient temperature and pressure, aldol adducts are generated under neutral conditions in the absence of any stoichiometric byproducts. Using cationic rhodium complexes modified by tri(2-furyl)phosphine, highly syn-diastereoselective reductive aldol additions of vinyl ketones are achieved. Finally, using novel monodentate TADDOL-like phosphonite ligands, the first highly diastereo- and enantioselective reductive aldol couplings of vinyl ketones were devised. These studies, along with other works from our laboratory, demonstrate that organometallics arising transiently in the course of catalytic hydrogenation offer byproduct-free alternatives to preformed organometallic reagents employed in classical carbonyl addition processes. 相似文献
15.
The tricyclic ketones 13 and 14, prepared from naphthalene and 2-methoxynaphthalene respectively, were subjected to reductive methylation in anhydrous ammonia to provide the β, γ -unsaturated ketones 16 and 17 in high yield which were stereoselectively converted into the A/B trans-fused compounds 3 and 4 respectively. 相似文献
16.
Ugo Azzena Giovanna Dettori Caterina Lubinu Alberto Mannu Luisa Pisano 《Tetrahedron》2005,61(36):8663-8668
Reduction of 1,2-diaryl-substituted ethenes with Na metal in dry THF allowed easy access to a variety of 1,2-diaryl-1,2-disodiumethanes. These diorganometallic intermediates were elaborated into the corresponding 1,2-diarylethanes (aqueous work up), or cycloalkylated with 1,3-dichloropropanes. The last reaction led to a highly diastereoselective synthesis of trans-1,2-diaryl-substituted cyclopentanes. 相似文献
17.
18.
Farajollah Mohanazadeh Mehdi Forozani Azam Taheri 《Monatshefte für Chemie / Chemical Monthly》2007,33(4):1187-1189
A new ionic liquid is presented as a medium and reducing agent for the reductive amination of aldehydes and ketones. 相似文献
19.
Farajollah Mohanazadeh Mehdi Forozani Azam Taheri 《Monatshefte für Chemie / Chemical Monthly》2007,138(11):1187-1189
Summary. A new ionic liquid is presented as a medium and reducing agent for the reductive amination of aldehydes and ketones. 相似文献
20.
Directed Asymmetric Nickel-Catalyzed Reductive 1,2-Diarylation of Electronically Unactivated Alkenes
Dr. Zhan Dong Qiongyao Tang Changyu Xu Li Chen Haiting Ji Sitian Zhou Dr. Liangliang Song Prof. Dr. Liang-An Chen 《Angewandte Chemie (International ed. in English)》2023,62(13):e202218286
Transition-metal catalyzed intermolecular 1,2-diarylation of electronically unactivated alkenes has emerged as an extensive research topic in organic synthesis. However, most examples are mainly limited to terminal alkenes. Furthermore, transition-metal catalyzed asymmetric 1,2-diarylation of unactivated alkenes still remains unsolved and is a formidable challenge. Herein, we describe a highly efficient directed nickel-catalyzed reductive 1,2-diarylation of unactivated internal alkenes with high diastereoselectivities. More importantly, our further effort towards enantioselective 1,2-diarylation of the unactivated terminal and challenging internal alkenes is achieved, furnishing various polyarylalkanes featuring benzylic stereocenters in high yields and with good to high enantioselectivities and high diastereoselectivities. Interestingly, the generation of cationic Ni-catalyst by adding alkali metal fluoride is the key to increased efficiency of this enantioselective reaction. 相似文献