共查询到20条相似文献,搜索用时 15 毫秒
1.
Kun Guo YANG Rui Mao HUA* Hai WANG Bo Qing XU* Department of Chemistry Tsinghua University Key Laboratory of Organic Optoelectronics & Molecular Engineering of Ministry of Education Beijing Department of Chemistry Chemical Engineering Guangxi Normal University Guilin 《中国化学快报》2005,16(4)
Diphenylmethane and substituted diphenylmethane are important compounds forsynthesis chemistry as well as industrial chemistry. These compounds are easilysynthesized by the benzylation of aromatic compounds with benzyl chloride or benzylalcohol catalyzed by homogeneous acid catalysts, such as AlCl3, FeCl3, H2SO4, HF andBF3. However, these catalytic systems are highly corrosive, and usually proceed withlow selectivity. In addition, they are less satisfactory from the environmen… 相似文献
2.
The [3+2] cycloaddition of a variety of diazo compounds with o-(trimethylsilyl)aryl triflates in the presence of CsF or TBAF at room temperature provides a very direct, efficient approach to a wide range of potentially biologically and pharmaceutically interesting substituted indazoles in good to excellent yields under mild reaction conditions. Simple diazomethane derivatives afford N-unsubstituted indazoles or 1-arylated indazoles, depending upon the stoichiometry of the reagents and the reaction conditions, while dicarbonyl-containing diazo compounds undergo carbonyl migration to afford 1-acyl or 1-alkoxycarbonyl indazoles selectively. 相似文献
3.
Hydrogen peroxide was supported on polyvinylpyrrolidone to afford a stable and mild oxidizing reagent.Acti-vated aromatic compounds were reacted with PVP-H_2O_2 in the presence of KI or I_2 and a catalytic amount ofH_3PW_(12)O_(40)in refluxing CH_2Cl_2 to afford the corresponding iodinated arenes. 相似文献
4.
5.
通过串联的不对称双Michael加成/分子内亲取代反应,一举得到了具有四个新手性中心的螺环/环丙烯类化合物(4).4在丙酮-5%HCl溶液中50℃下发生区域选择性单水解转换反应,得到螺[1-溴-4-羟基-5-氧杂-6-氧代双环[3.3.0]已-2,3'-(4'-亲核氧基-5'-孟氧基丁内酯)](5),化学产率53%~69%,光学纯度d.e≥98%.4在甲醇/TsOH催化下,实现了区域选择性单醇解转换反应,得到螺[1-溴-4-甲氧基-5-氧杂-6-氧代双环[3.1.0]已烷-2,3'-(4'-亲核氧基-5'-孟氧基丁内酯)](6),化学产率50%~78%,光学纯度d.e.≥98%.经元素分析,[α]D^20,UV,IR,1^HNMR,13^CNMR,MS以及X射线四圆衍射测定,确认了它们的化学结构。 相似文献
6.
L. V. Mikhal’chenko M. A. Syroeshkin M. Yu. Leonova A. S. Mendkovich A. I. Rusakov V. P. Gul’tyai 《Russian Journal of Electrochemistry》2011,47(11):1205-1210
The electrochemical behavior of 2-, 3-, and 4-nitrosonitrobenzenes (NNB) in DMF (with Bu4NClO4 suppoting salt) in the presence and in the absence of different proton donors (water, phenol, benzoic, acetic, chloroacetic,
and sulfuric acids) is studied by the methods of cyclic voltammetry, chronoamperometry and also by electrolysis at the controlled
potential. The electrochemical reduction of these compounds is shown to preferentially afford either monomeric (N-nitrophenylhydroxylamines)
or dimeric (azoxy compounds) products, which is determined by the interplay between reactions of protonation and dimerization
of NNB radical anions. The dimerization reactions proceed fast and reversibly to afford the corresponding dimeric dianions
with the basicity much higher as compared with NNB radical anions as the result of which the monomeric products are formed
in the presence of “strong” proton donors and the dimeric products form in the presence of “weak” proton donors. Like the
effective rate of formation of dimeric products, the basicity of radical anions increases in the row 4- < 3- < 2-NNB. 相似文献
7.
Pyrroles and indoles react smoothly with α-diazocarbonyl compounds in the presence of 10 mol% of InBr3 under mild conditions to afford the corresponding 2- and 3-alkyl pyrrole and 3-alkyl indole derivatives, respectively, in good yields with high selectivity. 相似文献
8.
Aromatic cycloimmonium ylides underwent smooth cyclization with electron deficient alkynes in presence of anhydrous K2CO3 in DMF solvent at room temperature to afford substituted indolizines. Ylides have also undergone expected cyclization with ethyl cyanoformate to produce imidazo[1,2-a]pyridines. The structures of these newly synthesized compounds have been confirmed by spectroscopic techniques and X-ray diffraction studies. 相似文献
9.
S. V. Popil'nichenko S. G. Pil'o B. S. Brovarets A. N. Chernega B. S. Drach 《Russian Journal of General Chemistry》2005,75(11):1816-1820
Addition products of carboxylic acid amides and trichloroacetaldehyde are readily converted into 3-arylsulfanyl-2-acylamino-3-chloroacrylonitriles which react with hydrazine hydrate to afford 3(5)-amino-5(3)-arylsulfanyl-4-acylaminopyrazoles. The presence of an amidine fragment in the latter makes them capable of undergoing cyclocondensations with β-dicarbonyl compounds and ethyl cyanoacetate. 相似文献
10.
Nishiyama Y Kawamatsu H Funato S Tokunaga K Sonoda N 《The Journal of organic chemistry》2003,68(9):3599-3602
A new synthetic method of organoselenium compounds has been developed. When phenyl tributylstannyl selenide (PhSeSnBu(3)) was allowed to react with acyl or aroyl chlorides in the presence of a catalytic amount of a palladium complex such as Pd(PPh(3))(4), Se-phenyl selenol esters were obtained in moderate to good yields. Similarly, the palladium complex catalyzed the reaction of PhSeSnBu(3) with alpha-halo carbonyl compounds to afford the corresponding alpha-phenyseleno carbonyl compounds in moderate yields. 相似文献
11.
Base-free catalytic alpha-alkylation of active methylene compounds with primary alcohols was successfully achieved using an [IrCl(cod)](2) complex in the presence of PPh(3) to afford the corresponding saturated alpha-alkylated products in good yields. 相似文献
12.
The epoxide 1 obtained by the Darzens condensation reaction of aldehydes with methyl dichloroacetate, reacted with aromatic compounds in the presence of aluminium chloride to afford α-aryl-β-chloro-α-hydroxyalkanoate 3. The intra-molecular nucleophilic addition of epoxide 1′ gave cyclisation compound 4. The scope and limitation of these reaction were studied for various aldehydes and aromatic compounds. The reaction was also studied in the presence of aluminium chloride supported on alumina or silica gel, which is thought to be a mild Lewis acid and harmless for environment. 相似文献
13.
Reductive esterification of aromatic aldehydes using Zn/Ac2O/imidazole or Zn/Yb(OTf)3/(RCO)2O system
Toshikazu Hirao Sirida SanthitikulHiroki Takeuchi Akiya OgawaHidehiro Sakurai 《Tetrahedron》2003,59(51):10147-10152
Benzaldehydes are reduced by metallic zinc in the presence of Ac2O and imidazole, giving the corresponding benzyl acetates in good yields. Reductive esterification of aromatic aldehydes is also carried out via gem-diacetoxy compounds. Carbonyl compounds are readily converted to the gem-diacyloxy compounds in excellent yields on treatment with 2 molar amounts of acid anhydride and 10 mol% of Yb(OTf)3 in MeCN at room temperature. Thus-formed diacyloxy compounds derived from aromatic aldehydes are reduced in situ by metallic zinc to afford the corresponding esters. 相似文献
14.
A wide variety of new macrocyclic diazocarbonyl compounds with various spacers was synthesized. Macrocyclic rhodium(II) carbenoid insertion with various substituted indoles was performed to afford regioselectively, indol-3-yl macrocyclic di- or tetralactones (C3-alkylation). Double carbenoid insertion was also performed to afford indolyl cryptand molecules. 相似文献
15.
Regioselective synthesis of 2-chloro-3-pyridinecarboxylates 总被引:3,自引:0,他引:3
Tony Y. Zhang James R. Stout James G. Keay Eric F.V. Scriven Joseph E. Toomey Gerald L. Goe 《Tetrahedron》1995,51(48):13177-13184
2-Chlorocyanoacetate was found to undergo base-catalyzed Michael addition to ,β-unsaturated ketones or aldehydes to afford 5-oxopentenenitrile derivatives. In the presence of anhydrous HCl, these compounds cyclize to yield 2-chloro-3-pyridinecarboxylates. The process is highly regiospecific and useful in the synthesis of 2,3-disubstituted pyridines. 相似文献
16.
Iodine/MeOH: a novel and efficient reagent system for thiocyanation of aromatics and heteroaromatics
Indoles, pyrroles, oxindoles and aromatic amino compounds undergo smooth thiocyanation with ammonium thiocyanate in the presence of molecular iodine in methanol under mild conditions to afford the corresponding 3-indolyl, 2-pyrrolyl and 4-aryl thiocyanates, respectively, in excellent yields with high selectivity. The reactions proceed rapidly at room temperature without heating or the use of strong Lewis acids. 相似文献
17.
Unexpected catalyst for Wittig-type and dehalogenation reactions 总被引:1,自引:0,他引:1
A novel catalyst 2 for Wittig-type and dehalogenation reactions was developed. In the presence of triphenyl phosphite, a wide variety of aldehydes could react with alpha-bromoacetates to afford alpha,beta-unsaturated esters or ketones in high yields with excellent E-stereoselectivity when 1-2 mol % of compound 2 was used. Compound 2 was also an effective catalyst for reductive dehalogenation of alpha-bromocarbonyl compounds. The mechanisms for the above reactions were also proposed. 相似文献
18.
Ameen A. Abu-Hashem Khadiga M. Abu-Zied Mohamed F. El-Shehry 《Monatshefte für Chemie / Chemical Monthly》2011,46(3):539-545
Abstract
The key intermediate ethyl 2-amino-5-benzoyl-4-methylthiophene-3-carboxylate was prepared by a Gewald reaction starting from benzoylacetone, sulfur, and ethyl cyanoacetate in the presence of diethylamine. This intermediate reacted with various reagents to afford different fused and polyfunctional substituted thiophenes. Antimicrobial screening of the synthesized compounds exhibited promising antimicrobial activities. 相似文献19.
Reaction of tri-O-acetyluridine (1) with benzyl bromide or 2-chloroacetophenone in the presence of K2CO3 gave the N3-substituted analogues 2a,c. Condensation of 1 with (+/-)-1-phenylethanol or 3,5-dimethylbenzyl alcohol using the Mitsunobu reaction also gave 2b,d in good yields. These compounds were allowed to react with Lawesson's reagent and were subsequently treated with ammonia to afford the 4-thiouracil derivatives 5a-d. Compounds 5a-c showed moderate hypnotic activity in mice. However, N3-(3,5-dimethyl)benzyl derivatives 3d, 5d were found to be almost inactive in this assay. 相似文献
20.
N. F. Eweiss 《Journal of heterocyclic chemistry》1982,19(2):273-277
2-Arylmethylene-l-indanones (I) and 2-arylmethylene-1,3-indanediones (VII) react with active methylene compounds in the presence of ammonium acetate as a basic catalyst to afford substituted pyridines. The postulated routes to the formation of the reported compounds are given. 相似文献