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1.
《Tetrahedron letters》1988,29(35):4365-4368
Tri-substituted enamines are oxidized to α-hydroxy ketones by N-sulfonyloxaziridines while di-substituted enamines are oxidized to α-amino ketones. A unified mechanism for the formation of both α-hydroxy ketones and α-amino ketones is proposed. 相似文献
2.
Magnus Engqvist 《Tetrahedron letters》2005,46(12):2053-2057
The novel, direct amino acid-catalyzed α-oxidation of ketones with iodosobenzene and N-sulfonyloxaziridines is presented. A screen of several synthetically common oxidants revealed that iodosobenzene and N-sulfonyloxaziridines act as electrophiles in the direct organocatalytic asymmetric α-hydroxylation of ketones. The direct proline-catalyzed asymmetric α-oxidation of ketones with iodosobenzene yielded the corresponding α-hydroxylated ketones with up to 77% ee. Furthermore, several amino acid derivatives catalyze the stereoselective α-oxidation of ketones with N-sulfonyloxaziridines. For example, the direct diamine-catalyzed enantioselective α-hydroxylation of ketones with N-sulfonyloxaziridines furnished the corresponding α-hydroxylated products in moderate yield with up to 63% ee. 相似文献
3.
Aromatic α-bromo ketones and α-iodio ketones can be reduced by bismuth prepared from NaBH4 and BiCl3 in water to their parent ketones in high yields, but aromatic α-chloro ketones should be added to sodium iodide first. 相似文献
4.
The Manganese(III)-based regioselective α′-keto radical generation of unsaturated ketones is a versatile synthetic procedure with broad applicability. The generated α′-keto radical slowly creates a metal enolate in a solvent at reflux. The resultant metal enolate affords the corresponding α′-allylated α,β-unsaturated ketones in good yields. This method is the first example of the metal mediated regioselective α′-allylation of α,β-unsaturated ketones. The ketones that have α or β-alkoxy groups also work efficiently. 相似文献
5.
In the presence of catalytic amounts of RhH(PPh3)4, 1,2-bis(diphenylphosphino)ethane (dppe), and dimethyl disulfide, ketones without α-activating groups were α-methylthiolated with 1,2-diphenyl-2-methylthio-1-ethanone giving α-methylthio ketones. The reaction of unsymmetrical ketones proceeded at the more substituted carbons. The initial formation of kinetic α-methylthiolated products followed by their rearrangement to thermodynamic products was observed in the reaction of α-phenyl ketones. Aldehydes, phenylacetate, and phenylacetonitrile were also α-methylthiolated under these conditions. 相似文献
6.
Takehiko Nishio Mitsuko Sugawara Yoshimori Omote 《Journal of heterocyclic chemistry》1979,16(4):815-816
β-Alkoxy- and β-alkylthio α,β-unsaturated ketones react with dimethylsulfonium methylide (DMSM) to give a furan, while β-anilino α,β-unsaturated ketones give the pyrrole. β,β-Bis(alkylthio) α,β-unsaturated ketones react with DMSM to afford the methylene inserted products, λ,λ-bis(alkylthio) β,λ-unsaturated ketones. 相似文献
7.
Jia Qiao Rui-Nan Ci Qi-Chao Gan Dr. Cheng Huang Dr. Zan Liu Hui-Lan Hu Dr. Chen Ye Dr. Bin Chen Prof. Dr. Chen-Ho Tung Prof. Dr. Li-Zhu Wu 《Angewandte Chemie (International ed. in English)》2023,62(29):e202305679
The activation of the α-C−H bond of ketones typically requires an amine and a directing group to guide the reaction selectivity in amine-catalysis carbonyl chemistry. For an α-C−H bond activation of ketone, directing groups are also required to control the reaction selectivity. Reported herein is the first α-alkylation of cyclic ketones in the absence of an amine catalyst and directing group. 1H NMR, XPS, EPR studies and DFT calculations indicate that an α-carbon radical intermediate is formed through direct and selective activation of the inert α-C−H bond of ketones chelating on the surface of colloidal quantum dots (QDs). Such an interaction is essential for weakening the C−H bond, as exemplified, using CdSe QDs as the sole photocatalyst to execute α-C−H alkylation of cyclic ketones under visible-light irradiation. Without an amine catalyst and directing group, the high step- and atom-economy transformation under redox-neutral condition opens a new way for α-C−H functionalization of ketones in carbonyl chemistry. 相似文献
8.
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
9.
Paraformaldehyde in a methanolic solution of KOH converts ketones into α-methoxymethylated and α- hydroxymethylated products. The method was tested on nine steroidal ketones. On prolonged treatment the ketones formed are reduced to alcohols. 相似文献
10.
Lun-Zhi Dai 《Tetrahedron letters》2009,50(6):651-5292
A convenient and efficient one-pot way to synthesize α,β-epoxy ketones directly from ketones and aldehydes has been described. Reactions were carried out at room temperature and the corresponding α,β-epoxy ketones were isolated in moderate to excellent yields. 相似文献
11.
Ji-Hong Hu 《合成通讯》2019,49(4):558-562
A facile method to synthesize 2-nitromethyl aromatic ketones was developed. In the method, benzyne was generated in situ for the insertion to α-Nitroketones in one pot to achieve 2-nitromethyl aromatic ketones under mild conditions. Aromatic and aliphatic α-nitroketones were applied in the reaction, and the results show that aliphatic α-nitroketones gave excellent yields (up to 96%), while aromatic α-nitroketones gave moderate yields. The synthesized 2-nitromethyl aromatic ketones could be potential substrates to synthesize isoindoles. 相似文献
12.
Huang K Li G Huang WP Yu DG Shi ZJ 《Chemical communications (Cambridge, England)》2011,47(25):7224-7226
A Suzuki-Miyaura coupling of α-pivaloxyl ketones via Ni-catalyzed sp(3) C-O activation to produce α-aryl ketones is developed. This study offers a convenient method to construct α-arylation products from readily available α-hydroxyl carbonyl compounds. 相似文献
13.
Insertion of arynes into C-C of α-sulfonyl ketones was investigated, which lead to the ring expansion reactions when α-sulfonyl cyclic ketones were used. By ring expansions and desulfonylations, medium- and large-sized benzannulated cyclic ketones were obtained in moderate yields. 相似文献
14.
A basic ionic liquid, 1-methyl-3-butylimidazolium hydroxide, [bmIm]OH, catalyzes the Michael addition of active methylene compounds to conjugated ketones, carboxylic esters and nitriles. It further catalyzes the addition of thiols to α,β-acetylenic ketones and alkylation of 1,3-dicarbonyl and -dicyano compounds. The Michael addition to α,β-unsaturated ketones proceeds in the usual way, giving the monoaddition products, whereas addition to α,β-unsaturated esters and nitriles leads exclusively to the bis-addition products. The α,β-acetylenic ketones undergo double conjugate addition with thiols producing β-keto 1,3-dithio-derivatives. In the alkylation reaction the acyclic 1,3-diketones are monoalkylated, whereas cyclic ketones undergo dialkylation under identical conditions. All these reactions were carried out without any organic solvent. The ionic liquid can also be recycled. 相似文献
15.
Qinglin Zhang Yongbin Duan Huifeng Guo Hong Yang Jiulong Zhai Tiantian Li Zhihai Wang Xiaolei Lu Yan Wang Prof. Yan Yin 《化学:亚洲杂志》2021,16(13):1832-1838
A Bi(OTf)3-catalyed reaction of 3-aryl propargyl alcohols with sulfonamide and halogen source was firstly investigated, which provided a facile route for the synthesis of a large variety of α-halo-β-amino ketones. The key intermediates, β-amino ketones, were obtained through tandem Meyer-Schuster rearrangement reaction of propargyl alcohols and intermolecular Michael addition of α, β-unsaturated ketones and sulfonamide. Then the in situ generated α-halo-β-amino ketones underwent the base-promoted intramolecular cyclization to give diverse acyl aziridines in a one-pot fashion. These transformations are reliable on a large scale. The high yields and convenient experimental operations make it a valuable method for the construction of α-halo-β-amino ketones and acyl aziridine derivatives. 相似文献
16.
A stereocontrolled synthesis of α-amino-α'-alkoxy ketones is described. This pH-neutral copper(I) thiophene-2-carboxylate (CuTC)-catalyzed cross-coupling of amino acid thiol esters and chiral nonracemic α-alkoxyalkylstannanes gives α-amino-α'-alkoxy ketones in good to excellent yields with complete retention of configuration at the α-amino- and α-alkoxy-substituted stereocenters. 相似文献
17.
The ozonolysis of substituted-allyl silyl ethers or -allyl esters followed by treatment with bases gave the corresponding α-silyloxy ketones or α-acyloxy ketones in good yields. The reaction is proposed to proceed via a novel ene-diol rearrangement of the corresponding α-silyloxy aldehydes or α-acyloxy aldehydes intermediates. 相似文献
18.
Asymmetric transfer hydrogenation of cyclic and acyclic α,β-unsaturated ketones catalysed by η6-p-cymene/ruthenium(II) and η5-pentamethylcyclopentadienyl/rhodium(III) complexes have been investigated. Cyclic α,β-unsaturated ketones appeared to be more suitable substrates for the synthesis of enantiomerically pure allylic alcohols than do acyclic α,β-unsaturated ketones. A proposed mechanism for the formation of 4-phenyl-[1,3]-dioxolan-2-one from α-tosyloxy- and halo-substituted acetophenones is discussed. The results of further investigations into the reduction of a range of α-tosyloxyacetophenones and the dynamic kinetic resolution of α-substituted ketones is presented. 相似文献
19.
Ketones react with an array of aldehydes in dioxane at 80 °C in the presence of a catalytic amount of RuCl2(PPh3)3 along with KOH to give the corresponding α-alkylated ketones in moderate to good yields. A reaction pathway involving base-catalyzed cross-aldol reaction between ketones and aldehydes to form α,β-unsaturated ketones and regioselective reduction of carbon-carbon double bond of α,β-unsaturated ketones is proposed for this catalytic process. 相似文献
20.
Ketones are directly converted to the corresponding α-iodoketones in good yields with molecular iodine under metal catalyst-free conditions. A significant difference in the reactivities was observed for aliphatic and aromatic ketones; whereas aliphatic ketones reacted smoothly at room temperature giving a mixture of 1-iodo, 3-iodo and 1,3-diiodoketones with predominant formation of the 3-iodo product, the α-iodination of aromatic ketones proceeded conveniently under heating to give good yields of α-iodo products. 相似文献