共查询到20条相似文献,搜索用时 13 毫秒
1.
Ibragimov A. G. Khafizova L. O. Zagrebel"naya I. V. Parfenova L. V. Sultanov R. M. Khalilov L. M. Dzhemilev U. M. 《Russian Chemical Bulletin》2001,50(2):292-296
A new method for the synthesis of dialkyl(ethyl)alanes by the reaction of EtAlCl2 with -olefins in the presence of Mg and a catalytic amount of Cp2TiCl2 (Ti(OPri)4, Ti(OBun)4) in THF was developed. 相似文献
2.
Hydroalumination of -olefins by non-solvated polymeric aluminum hydride (AlH3)
n
occurs at 120—140 °C. Mechanochemical activation accelerates this reaction. The addition of catalytic amounts of the prepared R3Al forms to the reaction system decreases the temperature of the process to 90—100 °C. The greatest initiation effect is observed when ate-complexes of the MAlR4 type (M = Li, Na) are used: the reaction occurs with a higher rate already at 60—90 °C affording R3Al free of admixtures of carbalumination products and dimers of -olefins. 相似文献
3.
Fujioka H Goto A Otake K Kubo O Sawama Y Maegawa T 《Chemical communications (Cambridge, England)》2011,47(35):9894-9896
An unusual and novel reaction of α-alkoxyphosphonium salts, generated from O,O-acetals and Ph(3)P, with Grignard reagents under an O(2) atmosphere afforded alcohols in moderate to high yields. It was clarified by isotopic labelling experiments that the reaction proceeded via a novel radical pathway. 相似文献
4.
Ramazanov I. R. Djyachenko L. I. Ibragimov A. G. Dzhemilev U. M. 《Russian Chemical Bulletin》2002,51(5):833-835
The reactions of olefins with alkyl halides and Et3Al in the presence of catalytic amounts of Cp2TiCl2 were studied. Unbranched -olefins of the aliphatic series underwent hydroalkylation under the action of tert-butyl bromide to form 2,3-dimethylalkanes. 相似文献
5.
A simple method for one-step preparation of the organoaluminum compounds R3Al, R2AlH, R2R"Al, and RR"AlH by the reaction of MAlH4 (M = Li, Na) with R2AlHal (Hal = Cl, Br) and -olefins (3-methylbut-1-ene, hex-1-ene, oct-1-ene, dec-1-ene) was proposed. 相似文献
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7.
U. M. Dzhemilev A. G. Ibragimov A. B. Morozov L. M. Khalilov R. R. Muslukhov G. A. Tolstikov 《Russian Chemical Bulletin》1991,40(5):1022-1025
An efficient method has been developed for the synthesis of a new class of organoaluminum compounds, trans-3,4-dialkyl-substituted aluminocyclopentanes, via the cyclometallation of -olefins using R3A1 in the presence of catalytic amounts of Cp2ZrCl2. Hydrolysis, deuterolysis, and oxidation of the resulting aluminocy-clopentanes generate the corresponding transformation products having exclusively the threo-configuration.For previous communication see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1141–1144, May, 1991. 相似文献
8.
Zhaoqin Jiang 《Tetrahedron letters》2010,51(14):1884-6740
Novel primary-tertiary diamine organocatalysts derived from l-serine were utilized to promote enantioselective aldol reaction of acetone with α-ketoesters. The desired products were obtained in high yields and with good to excellent enantioselectivities (up to 95% ee). 相似文献
9.
Haokun Pan Hua Li Huijun Liu 《Phosphorus, sulfur, and silicon and the related elements》2020,195(5):388-391
AbstractA mild, efficient and highly regioselective addition of trimethylsilyl cyanide (TMSCN) to α,β-unsaturated diesters has been achieved by using MgI2 etherate as catalyst under solvent-free conditions. This protocol provides the corresponding β-cyano esters in high yields. 相似文献
10.
Faiz Ahmed Khan Rashmirekha Satapathy Ch. Sudheer Ch. Nageswara Rao 《Tetrahedron letters》2005,46(42):7193-7196
A new reaction of diazomethane with norbornyl α-diketones in MeOH as solvent leading regioselectively to ketals is described. The mechanistic details of this intriguing reaction were investigated employing d4-MeOH, EtOH and d6-EtOH. The surprising observation of complete deuterium incorporation in the diazomethane-derived methoxy group was accounted for by sequential deuterium exchange between the initially formed hemiketal d4-18 and diazomethane in the presence of d4-MeOH as solvent. 相似文献
11.
K.R. Ajish B.P. Dhanya Nayana Joseph M. Priya Rani K.G. Raghu V.P. Vineetha K.V. Radhakrishnan 《Tetrahedron letters》2014
A new strategy for the synthesis of novel zerumbone derivatives via a regioselective palladium catalyzed decarboxylative coupling reaction using arene carboxylic acids is described. The current methodology involves the repositioning of endocyclic double bond to exocyclic double bond of zerumbone. Preliminary in vitro analysis revealed that most of the newly synthesized derivatives are potent α-glucosidase enzyme inhibitors. 相似文献
12.
A screen of aryloxy aminopropanol organocatalysts derived from the β-blocker inhibitor S-timolol determined the most active catalyst of asymmetric α-hydroxylation of β-keto esters. (R)-1-(tert-butylamino)-3-(3,4,5-trimethoxyphenoxy) propan-2-ol (3k) was the most effective derivative, enantioselectively catalyzing α-hydroxylation of β-keto esters using tert-butyl hydroperoxide as the oxidant in hexane to afford the corresponding products in excellent yield and with good enantioselectivity (up to 96% yield, 88% ee). 相似文献
13.
The asymmetric aza-Henry reaction of α-substituted nitroacetates and N-Boc imines was achieved with a new-type thioureaguanidine bifunctional organocatalyst.The novel transformations exhibited high diastereoselectivities,and the adducts bearing adjacent quaternary and tertiary chiral centers were generally obtained in moderate to good enantioselectivities(up to 88%ee). 相似文献
14.
D. Ravikumar S. Mohan Ch. Subramanyam 《Phosphorus, sulfur, and silicon and the related elements》2018,193(6):400-407
To obtain a rapid, efficient synthesis of some new α-aminophosphonates, ultrasonic irradiation has been applied to the reaction mixtures containing amine, aromatic or heteroaromatic aldehydes and triethyl phosphite. The Kabachnik-Fields reaction was performed by using nano-BF3?SiO2 as a recyclable catalyst under solvent free conditions. Key advantages of this procedure consist in the eco-friendly and highly efficient reaction conditions, high yields, an easy work-up procedure, short reaction times and solvent free conditions. All title compounds were characterized by spectral and elemental analysis. They were further screened for their in vitro antioxidant activity by the DPPH, O2? and NO methods. The majority of the title compounds showed good antioxidant activity when compared with the standard antioxidants. 相似文献
15.
Dimethyldimethoxysilane, methylphenyldimethoxysilane, and diphenyldimethoxysilane have been synthesized by a one-step, simple
method and used as catalysts in the Henry reaction with Cu(OAc)2·H2O and Zn(OAc)2·2H2O, affording 60–96% conversion under the optimum catalytic conditions. 相似文献
16.
Enantioselective α-chlorination of β-oxo esters catalyzed by chiral diterpenoid alkaloid derivatives
《Tetrahedron: Asymmetry》2014,25(16-17):1215-1220
Easily accessible diterpenoid alkaloid derivatives have been used as organocatalysts in the enantioselective α-chlorination of β-oxo esters. The treatment of β-oxo esters with N-chlorophthalimide (NCP) as a chlorine source under mild reaction conditions afforded the corresponding α-chlorinated β-oxo esters in excellent yields (up to 98%) and with moderate enantioselectivities (up to 68% ee) in 30 min. 相似文献
17.
V. I. Boev A. I. Moskalenko S. L. Belopukhov G. N. Nikonova 《Russian Journal of Organic Chemistry》2016,52(5):628-635
Decarboxylation of α-allyl-substituted acetoacetic esters afforded α-allyl ketones that were reduced with L-selectride [LiBH(s-Bu)3] in alcohols RCH(OH)CH2CH2CH=C(Me)CH2R'. The latter reacted with methyl 4-hydroxy-3-formylbenzoate and methyl orthoformate in the presence of p-toluenesulfonic acid to provide trans-tetrahydropyrano[3,2-с][1]benzopyran. In reaction of the E-isomer of alcohol Me2CHCH(OH) CH2CH2CH=C(Me)CH2CH2Ph with CF3SO3H a stereoselective cyclization occurred with the formation of 2,6-disubstituted tetrahydropyran; Prins reaction with 4-bromobenzaldehyde and salicylaldehyde in the presence of boron trifluoride etherate also proceeded stereoselectively giving a substituted tetrahydropyrano-[3,2-c][1]-benzopyran. 相似文献
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19.
Maetani S Fukuyama T Suzuki N Ishihara D Ryu I 《Chemical communications (Cambridge, England)》2012,48(19):2552-2554
The catalytic decarbonylation reaction of aliphatic carboxylic acids can be carried out in the presence of an iron complex, and it proceeds smoothly to give α-olefins with high selectivity. 相似文献
20.
Trimerization of 2-methylpropanal (isobutyraldehyde) is a simple and effective method to synthesize 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate and 2,2,4-trimethyl-1,3-pentanediol-3-monoisobutyrate which are often used as film forming auxiliaries in paints. The use of solid sodium hydroxide as a catalyst provides an excellent yield of above 85 % after the optimization of the reaction time and the catalyst dosage. Furthermore, trimerization of four other aldehydes with one α-hydrogen catalyzed by solid sodium hydroxide can also take place and the yield of 1,3-diol monoesters reaches 50–70 %. Trimerization of aldehydes with one α-hydrogen can be explained by a three-step reaction mechanism: (i) aldol condensation of aldehyde; (ii) crossed Cannizzaro reaction; and (iii) esterification of carboxylic acid and alcohol. 相似文献