共查询到20条相似文献,搜索用时 15 毫秒
1.
A one-pot synthesis of N-substituted 3,3,3-trifluoroalanine esters from alkyl trifluoropyruvates and carboxamides or substituted ureas was developed. 相似文献
2.
Stanisaw Krompiec Robert Penczek Mateusz Penkala Micha Krompiec Jzef Rzepa Marek Matlengiewicz Joanna Jaworska Stefan Baj 《Journal of molecular catalysis. A, Chemical》2008,290(1-2):15-22
Addition of alcohols and phenols to allyl ethers catalyzed mainly by ruthenium complexes was studied. Complexes of ruthenium generated in situ from precursors such as {[RuCl2(1,5-COD)]x} or [Ru3(CO)12] and from external ligands such as phosphines (e.g. PPh3, PBu3, BINAP) or phosphites (e.g. P(OPh)3, P(OMe)3) were found to be particularly efficient catalysts of the studied reactions. Transacetalization reaction could be practically completely eliminated by the addition of a base (particularly Na2CO3) to the catalytic systems. It was observed that the selectivity of mixed acetals formation increases with increasing value of Θ parameter of phosphines. Especially interesting results (0–5% of transacetalization) have been obtained for catalytic systems generated from {[RuCl2(1,5-COD)]x} or [Ru3(CO)12], phosphines (PPh3, BINAP, dppe, tris(2,4,6-tri-metylphenyl)phosphine, or dppf) and Na2CO3. The mechanism of mixed acetals formation has been investigated using deuterated reagents. It is postulated that the examined reaction is a nucleophilic addition of ROH to a hydrido-π-allyl complex formed during oxidative addition of allyl substrate to metal complex. As a result, a new, selective, and convenient method of the synthesis of symmetrical and, in particular, unsymmetrical (mixed) acetals has been developed. Mixed acetals CH3CH2CH(OR1)(OR2) may be obtained in the reaction of R1-O-allyl with R2OH or R1OH with R2-O-allyl, depending on the structure of R1 and R2. 相似文献
3.
Polina Angelova Kalina Kostova Karsten Hinrichs Dimiter Tsankov 《Central European Journal of Chemistry》2005,3(4):658-667
New 4-substituted benzyl esters of 16-mercaptohexadecanoic acid were prepared by developing a practicable synthetic procedure
and using readily available staring materials. The compounds synthesized have been characterized by NMR, MS, IR spectra and
elemental analysis. The mercapto derivatives are precursors for the formation of self-assembled monolayers on metal substrates.
Dedicated to Professor Dr. Manfred Hesse on the occasion of his 70
th
birthday 相似文献
4.
Renate Drozdzak Nele Ledoux Bart Allaert Ileana Dragutan Valerian Dragutan Francis Verpoort 《Central European Journal of Chemistry》2005,3(3):404-416
A two step procedure for the synthesis of a novel family of homogeneous and immobilized Ru-complexes containing Schiff bases
as O,N-bidentate ligands is described. The new Ru-complexes have been structurally characterized by IR, Raman,1H-,13C-NMR spectroscopy. The Schiff bases were associated with a diversity of inorganic and organic ligands such as chloride, phosphane,
arenes, various carbenes (alkylidene, vinylidene, indenylidene and allenylidene as well as N-heterocyclic carbenes) and cyclodienes.
By choosing a selective range of substituents for the Schiff base, useful physical and chemical properties of the prepared
Rucomplexes can be induced. This synthetic approach is promising in creating a valuable and diverse selection of Ru-complexes,
valuable for future applications. 相似文献
5.
Marko Kirilov Galin Petrov Atanass Sidjimov 《Monatshefte für Chemie / Chemical Monthly》1980,111(6):1351-1358
Metallation of diethyl ester of 1-propynephosphonic acid (1-DEPP) is achieved by treatment with alkaline amides, calcium amid and calcium in liquid ammonia, with isopropylmagnesium chloride in ether or via metal exchange from the potassium derivative of 1-DEPP with copper(II) and cobalt(II) chloride resp.On the basis of IR-and1H-NMR-spectra the calcium derivative appears as a mixture of an allene and its isomeric acetylene. The IR-spectrum of the lithium derivative is consistent with an analogous phenomenon while an acetylene structure is attributed only to the cobalt and copper derivatives. The alkylation of the potassium derivative with alkyl halides and the hydroxy-alkylation with benzaldehyde occur with low yield at the -position of the parent compound. 相似文献
6.
Manouchehr Saljoughian 《Monatshefte für Chemie / Chemical Monthly》1984,115(4):519-521
Purified partially mono-deuteriatedTMS was synthesized by preparing lithiomethyltrimethylsilane from chloromethyltrimethylsilane and reaction of the former with deuteriated water. Using this reference deuterium chemical shifts in parts per million can be reported with respect to [2H] resonance frequency of internalTMS in deuterium nmr spectroscopy.
Eine einfache zweistufige Synthese von monodeuteriertem Tetramethylsilan (Kurze Mitteilung)
Zusammenfassung Es wird die Synthese von partiell monodeuteriertemTMS beschrieben. Dazu wurde Monochlormethyltrimethylsilan in Lithiomethyltrimethylsilan übergeführt und dieses mit D2O weiter zum Zielprodukt umgesetzt.相似文献
7.
Two further aporphine alcaloids, N-methyllaurotetanine and boldine, were used to the synthesis of aristolochic acid analogs. By means of their destruction and nitration of the reaction products two new nitrophenanthrene acids were obtained and their chemical structures were proved. 相似文献
8.
A general and convenient synthesis of N-aryl piperazines from bis(2-chloroethyl)amine hydrochloride and a broad range of anilines in diethylene glycol monomethyl ether is described. 相似文献
9.
Ren Hua Zheng Hai Chang Guo Hua Jiang Jiang Ke Hui Xu Bei Bei Liu Wei Lin Sun Zhi Quan Shen 《中国化学快报》2010,21(11):1270-1272
<正>A new method is described to synthesize phendione derivatives from 1,10-phenanthrolines using potassium bromate and 60% sulfuric acid as oxidant,which was easily applicable to scale-up.The reaction conditions are mild and the yields are excellent.The target compounds have been characterized by ~1H NMR,and IR. 相似文献
10.
A method for the synthesis of substituted 2,3-dioxo-1,2,3,4-tetrahydroquinoxalines by the reduction of substituted (o-nitrophenyl)glycines
with subsequent oxidation of the 2-oxo-1,2,3,4-tetrahydroquinoxaline products has been developed. When tin(II) chloride was
used as the reducing agent a chlorine atom was introduced ortho to the NHC(O) fragment of the heterocycle.
__________
Translated from Khimiya Geterotsikicheskikh Soedinenii, No. 8, 1206–1210, August, 2006. 相似文献
11.
Amol A. Thorave Pinkal N. Prajapati Jignesh P. Pethani Krunal C. Kothari Mukul R. Jain Pankaj R. Patel Rajendra K. Kharul 《Tetrahedron letters》2009,50(40):5660-5663
Convenient synthesis of 4-substituted 2-aminothiazolo[4,5-d]pyridazinones has been achieved in 12 steps with overall yield of 19% by employing Grignard reaction as the key step. The route utilizes well established thiazole ring formation followed by Grignard reaction to introduce substitution at 4-position effectively. In addition to the use of inexpensive chemicals, the present route first time gave access to the 4-substituted 2-aminothiazolo [4,5-d]pyridazinones with free amino group at C-2 position. 相似文献
12.
Summary A semisynthetic route to produce hypericin was established usingCortex frangulae as the starting point. The emodin isolated from it easily and in good yield was reduced to emodin anthrone by means of SnCl2. The latter was reacted via a known oxidative dimerization and photocyclization reaction into hypericin.
Ein bequemer semisynthetischer Zugang zu Hypericin
Zusammenfassung Eine semisynthetische Route zur Darstellung von Hypericin unter Verwendung vonCortex frangulae als Ausgangsmaterial wurde erarbeitet. Das daraus einfach und in guten Ausbeuten isolierte Emodin wurde mit Hilfe von SnCl2 zu Emodinanthron reduziert. Letzteres wurde dann über eine bekannte oxidative Dimerisierung und Photocyclisierung zu Hypericin umgesetzt.相似文献
13.
Siegfried Biedermann Hans Bürger Karl Hassler Friedrich Höfler 《Monatshefte für Chemie / Chemical Monthly》1980,111(3):703-714
The infrared andRaman spectra of theM(CH3)4 andM(CD3)4 species,M=Si, Ge, Sn and Pb, have been reinvestigated. The spectra of the mixed tetramethyl compounds (CH3)3
MCD3,M=Si, Ge, Sn and Pb, and of (CH3)2Si(CD3)2 and CH3Si(CD3)3 have been recorded in the gaseous (i.r.) and liquid states (Raman). The proposed assignment is supported by a normal coordinate analysis. 相似文献
14.
A simple method is described for the preparation of 3-aryl-2-thioxo-4(3H)-quinazolinones (4) by the reaction of anthranilic acids and ammonium or triethylammonium N-aryl-dithiocarbamates in ethanol. The method is
also applicable to the preparation of 3-ethyl-2-thioxo-4(3H)-quinazolinone. 相似文献
15.
In the nearly unknown class of cyclosilanes with one heteroatom, decaphenyl-oxa-cyclohexasilane was prepared for the first time by removing of water. The diol was prepared by hydrolysis of the corresponding 1,5-dichlorocompound. Cyclisation was not successful with 1,5-Di(ethylamine)decaphenylpentasilane, which was prepared also for the first time. Spectroscopic data were determined of all synthesized compounds.
Herrn Prof. Dr.G. Zigeuner zum 60. Geburtstag gewidmet. 相似文献
16.
Matthias Pailer Eveline Schaffer Irene Schläger 《Monatshefte für Chemie / Chemical Monthly》1979,110(3):589-592
The synthesis of the ,-unsaturated ketones4, 5 und6
via the regiospecific aldol- andWittigreaction with some indolealdehydes is described.4 and5 are stable enough for NaBH4-reduction to the corresponding alcohols. 相似文献
17.
Wolfgang Reischl 《Monatshefte für Chemie / Chemical Monthly》1989,120(12):1185-1188
Summary The title compound was prepared in three steps from 25-hydroxyvitamin D3. The keystep in this sequence is the transformation of3b to4 by means of the LiBr/HMPT complex.Dedicated to Prof. Dr. Karl Schlögl on the occasion of his 65th anniversary 相似文献
18.
Yuri N. Stefanovsky Lilia Z. Viteva 《Monatshefte für Chemie / Chemical Monthly》1980,111(6):1287-1298
The NaNH2 catalyzed one stage reaction between phenylacetic acid dialkylamides and cinnamic acid methyl ester or dialkylamides was studied under various conditions. Conditions were found for easy preparation of each of the both possible diastereomeric derivatives of 2,3-diphenylglutaric acid. It was proved that catalytic amounts of NaNH2 take part in the reaction. It is assumed that the observederythro/threo equilibrium ratios are determined by an isomerization via two different carbanions (at C2 and C4) of the reaction products.Part III:J. Stefanovsky andL. Viteva, Comun. Dept. Chem. Bulg. Acad. Sci.4, 159 (1971). 相似文献
19.
J.A. PariharM.M.V. Ramana 《Tetrahedron letters》2003,44(9):1843-1845
Imidazolidine-2,4-dione was chemoselectively N-alkylated at the imidic NH with several 2-(3,4-dihydro-1-naphthalenyl)ethyl-4-methylphenylsulphonates to give the corresponding imides for the first time which on selective reduction at one of the carbonyl groups followed by cyclization in PPA gave the corresponding title compounds. 相似文献
20.
Werner W.K.R. Mederski Manfred BaumgarthMartina Germann Dieter KuxThomas Weitzel 《Tetrahedron letters》2003,44(10):2133-2136
An efficient one-step synthesis of 4-nitro-N-aryl substituted glutarimides, succinimides and maleimides in polyphosphoric acid is described together with the subsequent reduction to the corresponding anilines. The scope and limitation of this cyclocondensation are presented. 相似文献