- Synthesis method of alpha or beta-substituted aromatic ketone
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The invention discloses a synthesis method of alpha-or beta-substituted aromatic ketone. The method comprises the following steps: under the condition of inert gas, reacting alpha-oxo-aryl ethanone compounds, B2pin2, PDI-CoCl2 and MBHEt3 in an organic solvent at room temperature, then adding a compound 2, and continuously reacting to obtain a compound 3, wherein in the MBHEt3, M is an alkali metal; the compound 2 is selected from the group consisting of deuterated methanol, Selectfluoro, a TogniII reagent or R2CHO; R2 is an aromatic substituent or alkyl; the organic solvent is an aprotic organic solvent. According to the method, the alpha-oxo aryl ethanone is used as a raw material, a cheap and stable boron reagent and an efficient cobalt catalyst which is cheap and easy to obtain are used, an activating reagent MBHEt3 is added to generate an enol boron ether intermediate, then the enol boron ether intermediate and different electrophilic reagents are synthesized into alpha-or beta-substituted aromatic ketone, the reaction is carried out at normal temperature, and the operation is convenient.
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Paragraph 0022-0027; 0071-0075
(2021/05/01)
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- Enantioselective Conjugate Azidation of α,β-Unsaturated Ketones under Bifunctional Organocatalysis by Direct Activation of TMSN3
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An enantioselective organocatalytic conjugate azidation of α,β-unsaturated ketones is presented. A bifunctional organocatalyst activates TMSN3, triggering the nucleophilic addition of the azido group to enones in absence of external promoters and avoiding the direct use or the pre-formation of highly toxic and explosive hydrazoic acid. This protocol proceeds with excellent enantiocontrol under mild conditions. DFT calculations and mechanistic trials have been performed in order to demonstrate the direct activation performed by the bifunctional organocatalyst. (Figure presented.).
- Humbrías-Martín, Jorge,Pérez-Aguilar, M. Carmen,Mas-Ballesté, Rubén,Dentoni Litta, Antonella,Lattanzi, Alessandra,Della Sala, Giorgio,Fernández-Salas, Jose A.,Alemán, José
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supporting information
p. 4790 - 4796
(2019/09/16)
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- Method for preparing organoboron compound under catalytic effect of chitosan immobilized copper and application
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The invention discloses a method for preparing an organoboron compound under a catalytic effect of chitosan immobilized copper and an application. The method comprises the following steps: A) adding a chitosan immobilized copper catalyst and a ligand into a reaction tube and stirring; B) respectively continuously adding an initial raw material I and bisdiboron into a system in turn; C) stirring the whole reaction system and reacting under room temperature; D) after the reaction is ended, filtering the whole reaction system, washing with tetrahydrofuran, performing rotary evaporation and concentration on a filtrate, adopting a mixed solvent of ethyl acetate and petroleum ether at different ratios for performing column chromatography on the residues, separating and purifying, thereby acquiring a target product II. The silica gel is taken as a fixing phase for column chromatography. The invention also relates to the application of the prepared organoboron compound in compounding beta-hydroxy compound and anti-cancer drug molecules. The method is feasible; the operation is simple and convenient; the method is suitable for various substrates and can be used for successfully preparing the corresponding target compounds. The catalyst is low in dosage and is recyclable, is easily separated after the ending of the reaction, is free from metal residue and is suitable for large-scale production.
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Paragraph 0121; 0122; 0123; 0124; 0125; 0126
(2017/07/21)
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- A green and recyclable chitosan supported catalyst for the borylation of α,β-unsaturated acceptors in water
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We herein report a green and recyclable chitosan supported copper catalyst which is capable of catalyzing the borylation of α,β-unsaturated acceptors in water at room temperature. A broad substrate scope including chalcone derivatives, esters and nitriles have been explored. In all the cases, desired products were obtained in good to excellent yields. Remarkably, this chitosan supported catalyst could be recovered and reused for five times without any significant decrease of reactivity.
- Xu, Pengyu,Li, Bojie,Wang, Liansheng,Qin, Caiqin,Zhu, Lei
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- Mukaiyama aldol reactions catalyzed by a trimeric organo aluminum(III) alkoxide
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Mukaiyama aldol reactions of enol ethers with a variety of aldehydes and ketones are efficiently catalyzed at 0-25 °C by the sterically bulky trimeric organo aluminum(III) alkoxide 1 synthesized via the reaction of 3 equiv of AlMe3 with tripodal tris(2-hydroxy-3-tert-butyl-5-methylphenyl) methane and the elimination of 3 equiv of methane. Comparisons of its catalytic properties with the less sterically hindered analogue 2, the more sterically hindered analogue 3, a monomeric aluminum near-analogue 4, and a dimeric alumatrane 5 revealed that 1 possesses superior activity.
- Kim, So Han,Yoon, Sungwoo,Kim, Youngjo,Verkade, John G.
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p. 1193 - 1206
(2014/09/30)
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- Development of N,N-bis(perfluoroalkanesulfonyl)squaramides as new strong Br?nsted acids and their application to organic reactions
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New strong Br?nsted acids derived from a squaric acid scaffold bearing different perfluoroalkanesulfonyl groups have been developed and applied to several organic reactions. These squaramides are bench-stable and exhibit much higher reactivities in several organic reactions than squaric acid itself. N,N-Bis(trifluoromethanesulfonyl)squaramide 2a was applied to the Mukaiyama aldol reaction and Mukaiyama Michael reaction. Mechanistic studies revealed that the Br?nsted acid might be the predominant catalyst through direct protonation of carbonyl compound by the acid itself rather than the silylated Br?nsted acid. The utility of this acid 2a was further extended to Hosomi-Sakurai allylation of aldehydes and a carbonyl-ene reaction. Furthermore, other squaramides 2b and c bearing longer perfluoroalkyl chains have been developed, which are also bench-stable and displayed similar reactivities with squaramide 2a in several organic reactions.
- Cheon, Cheol Hong,Yamamoto, Hisashi
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supporting information; experimental part
p. 4257 - 4264
(2010/07/06)
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- P(PhCH2NCH2CH2)3N catalysis of Mukaiyama aldol reactions of aliphatic, aromatic, and heterocyclic aldehydes and trifluoromethyl phenyl ketone
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(Chemical Equation Presented) Herein we find that proazaphosphatrane 1c is a very efficient catalyst for Mukaiyama aldol reactions of aldehydes with trimethylsilyl enolates in THF solvent. Only the activated ketone 2,2,2-trifluoroacetophenone underwent clean aldol product formation with a variety of trimethylsilyl enolates under similar conditions as the aldehydes. The reactions were carried out at room temperature using (1-methoxy-2-methyl-1- propenyloxy)trimethylsilane, whereas the temperature was -15 °C in the case of 1-phenyl-1-(trimethylsilyloxy)ethylene. The reaction conditions are mild and operationally simple, and a variety of aryl functional groups, such as nitro, amino, ester, chloro, trifluoromethyl, bromo, iodo, cyano, and fluoro groups, are tolerated. Product yields are generally better than or comparable to those in the literature. 1-Phenyl-1-(trimethylsilyloxy)ethylene, 1-(trimethylsilyloxy) cyclohexene, and 2-(trimethylsilyloxy)furan underwent clean conversion to β-hydroxy carbonyl compounds under our reaction conditions. In the case of bulky (2,2-dimethyl-1-methylenepropoxy)trimethylsilane, only α,β-unsaturated esters were isolated. Heterocyclic aldehydes, such as pyridine-2-carboxaldehyde, benzofuran-2-carboxaldehyde, benzothiophene-2- carboxaldehyde, and 1-methyl-2-imidazolecarboxaldehyde, gave good yields of Mukaiyama products. An optimized synthesis for the catalyst 1c is also reported herein. 2009 American Chemical Society.
- Chintareddy, Venkat Reddy,Wadhwa, Kuldeep,Verkade, John G.
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experimental part
p. 8118 - 8132
(2010/02/28)
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- Reduction of β-hydroxyketones by Sml2/H2O/ Et3N
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(Chemical Equation Presented) Reduction of a series of β- hydroxyketones by Sml2/H2O/Et3N provided 1,3-diols in quantitative yields. The reactions were exceedingly clean with no byproduct formation, negating the need for f
- Davis, Todd A.,Chopade, Pramod R.,Hilmersson, Goeran,Flowers II, Robert A.
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p. 119 - 122
(2007/10/03)
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- Albumin-controlled stereoselective reduction of 1,3-diketones to anti-diols
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An unprecedented combination of high chemo- and stereoselectivity in the NaBH4 reduction of 1:1 complexes between albumin and aromatic 1,3-diketones results in the formation of anti 1,3-diols with de up to 96%.
- Benedetti, Fabio,Berti, Federico,Donati, Ivan,Fregonese, Massimo
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p. 828 - 829
(2007/10/03)
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- Reformatsky-type reaction of α-haloketones promoted by titanium tetraiodide
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Titanium(IV) tetraiodide induces a Reformatsky-type reaction of α-iodoketones with carbonyl compounds to give β-hydroxy ketones in good to high yields.
- Shimizu, Makoto,Kobayashi, Fumiko,Hayakawa, Ryuuichirou
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p. 9591 - 9595
(2007/10/03)
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- Aluminum bis(trifluoromethylsulfonyl)amides: New highly efficient and remarkably versatile catalysts for C-C bond formation reactions
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Superacid-derived aluminum catalysts R2AlNTf2 (2-5 mol%) are highly efficient and versatile and are suitable promoters for the allylation and pentadienylation of aldehydes, aldol reactions, aldol cross-coupling of ketones, and Michae
- Marx, Andreas,Yamamoto, Hisashi
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p. 178 - 181
(2007/10/03)
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- Homogeneous catalysis. Transition metal based lewis acid catalysts
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Transition metal based Lewis acids provide catalysts for the Diels-Alder and Mukaiyama reactions. These catalysts must possess an electron deficient axophilic metal center and a labile coordination position. Unlike traditional Lewis acids, those derived from transition metals can function in the presence of water and have well defined structures. It is shown how a normally electron rich ruthenium atom can be converted to a Lewis acid by incorporation of electron withdrawing ligands and ligands with hard donor atoms. This ruthenium complex, [Ru(salen)(NO)(H2O)]+, is an efficient catalyst for the Diels-Alder reaction, but in the Mukaiyama reaction, it tends to be reduced and thereby deactivated by the silyl enol ether. It is shown that the complex [TiCp*2(H2O)2]2+ (Cp* is pentamethylcyclopentadienyl) is an efficient catalyst for the Diels-Alder reaction even when water is present. Similarly, the triflato complexes [TiCp2(CF3 SO3)2] and [ZrCp2(CF3SO3)2] (Cp is cyclopentadienyl) are efficient catalysts for both the Diels-Alder and Mukaiyama reactions. All of these catalysts are effective at very low loadings of ≈ 1 mol%. Catalysis has been shown to occur via substrate-catalyst adducts and moreover these adducts are formed rapidly and reversibly as required for efficient catalysis.
- Hollis, T. Keith,Odenkirk, William,Robinson,Whelan, John,Bosnich
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p. 5415 - 5430
(2007/10/02)
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- Novel Reactive Silyl Enolates. Highly Stereoselective Aldol and Michael Reactions without Catalysts
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Novel silyl enolates, prepared in situ from ketones and dimethylsilyl ditriflate (Me2Si(OTf)2) in the presence of a tertiary amine, reacted smoothly with electrophiles such as aldehydes, acetals, or α,β-unsaturated ketones without catalyst at -78 deg C to
- Kobayashi, Shu,Nishio, Koichi
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p. 2647 - 2649
(2007/10/02)
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- STUDIES ON THE DIASTEREOSELECTIVE REDUCTION OF β-HYDROXY KETONES TO 1,3-DIOLS WITH COMMON HYDRIDE REAGENTS
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Some common reducing agents were employed in the diastereoselective reduction of several β-hydroxy ketones to their corresponding syn-1,3-diols.The use of NaBH4 with a Ti(IV) chelating species produced syn diols with a moderate to good selectivity significantly depending upon the reaction conditions chosen (solvent, temperature, nature of the titanium species).The use of LiAlH4 at low temperature, in the presence of LiI, showed a high selectivity for reduction to syn diols, thus demonstrating a possible chelating role of lithium.Some interesting preliminary results have been also obtained in the diastereoselective reduction of MEM-protected β-alkoxy ketones.
- Bonini, Carlo,Bianco, Armandodoriano,Fabio,Romano Di,Mecozzi, Sandro,Proposito, Alessandro,Righi, Giuliana
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- Lewis acid-promoted cross aldol reaction of aldehydes with ketones utilizing 3-methyl-2-phenyl-2-(2-oxoalkyl)benzothiazolines as an enolate-transferring reagent
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The treatment of a variety of 3-methyl-2-phenyl-2-(2-oxoalkyl) benzothiazolines with aldehydes in the presence of 2 equivalents of SnCl4 in dichloromethane at -78°C underwent a carbon-carbon bond cleavage at the 2-position of the benzothiazolin
- Chikashita,Tame -i.,Yamada,Itoh
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p. 497 - 501
(2007/10/02)
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- NOVEL ALDOL-TYPE REACTION UTILIZING 3-METHYL-2-PHENYL-2-(2-OXOALKYL)BENZOTHIAZOLINE AS AN ENOLATE TRANSFERRING REAGENT
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An enolate transfer-type aldol reaction of the title benzothiazoline with aldehydes was successfully achieved in the presence of SnCl4 to afford the cross aldol products.
- Chikashita, Hidenori,Tame, Shin-ichiro,Itoh, Kazuyoshi
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