共查询到20条相似文献,搜索用时 15 毫秒
1.
Janine Cossy Haja Rakotoarisoa Philippe Kahn Jean-Roger Desmurs 《Tetrahedron letters》1998,39(52):3240-9674
The synthesis of functionalized 2,2-disubstituted 2H-1-benzopyrans was achieved by condensing 2,3,5-trimethylhydroquinone (TMHQ) with ,β-unsaturated aldehydes or ,β-unsaturated acetals under acidic conditions. 相似文献
2.
Lin WW Jang YJ Wang Y Liu JT Hu SR Wang LY Yao CF 《The Journal of organic chemistry》2001,66(6):1984-1991
Reactions of ketones 1, nitromethane 2, and catalytic amount of piperidine 3 in the presence of mercaptan 6 generate beta-nitroalkyl sulfides 7-9. At 0 degrees C and by the use of dichloromethane as solvent, beta-nitroalkyl sulfides 7-9 can be oxidized by m-chloroperoxybenzoic acid (m-CPBA) 10 to generate beta-nitroalkyl sulfoxides 11-13 and undergo elimination in carbon tetrachloride solution to produce medium to high yield of 2,2-disubstituted 1-nitroalkenes 5. The irreversibility of the synthetic mechanism not only can overcome the reversibility of the Henry reaction in the synthesis of 2,2-disubstituted 1-nitroalkenes 5 but also can generate the major products "exo-nitro olefins"5c-e when cyclic ketones 1c-e were used. Under similar conditions, medium to high yield of 5-substituted-2-nitromethyl-2-phenylthioadamantane 17 also can be prepared from the reaction of 5-substituted-2-adamantanones 15, nitromethane 2, piperidine 3, thiophenol 6a. The intermediate17 can be oxidized by m-CPBA 10 in dichloromethane solution and then undergo elimination at room temperature or can be dissolved in solvent, coated on silica gel, and then heated at 90-100 degrees C to generate 5-substituted-2-nitromethyleneadamantane 16. 相似文献
3.
Treatment of diethyl 2-(3-mesyloxypropyl) malonate with KSCOCH3/DMF at room temperature gave 2,2-dicarbethoxytetrahydrothiophene. The reaction can be used to prepare isopenams in good yield. 相似文献
4.
Copper is found to be an effective catalyst for the preparation of alkynylphophonates. A novel copper-catalyzed one-pot synthesis of alkynylphophonates from terminal alkynes and dialkyl phosphites is developed which involves the haloalkynes intermediates. This method provides a unique and alternative approach to the well-documented oxidative coupling or arylpropiolic acid strategies. 相似文献
5.
以3-(4-氯磺酰苯基)-2,3-二溴丙酸和氨水(2.2 eq)为原料,以 DMF为溶剂,经微波辐射25 s,磺酰胺化和脱溴脱羧反应可同步进行,立体选择性地合成中间体(Z)-4-(2-溴乙烯基)苯磺酰胺;该中间体不需分离,直接向反应体系中加入1,8-二氮杂环[5,4,0]十一烯-7 (DBU,2eq),再微波辐射1 min,“一锅法”得到4-乙炔基苯磺酰胺,并通过1H NMR和13C NMR和IR进行了表征,收率达70%。 相似文献
6.
Keng Yoon Yeong Mohamed Ashraf Ali Chee Wei Ang Soo Choon Tan Hasnah Osman 《Tetrahedron letters》2014
A facile method to synthesize various 1,2-disubstituted benzimidazoles is developed. It is suggested that formation of a Meisenheimer adduct between the substrate, amine, and solvent aids the N-arylation process. The generality of the protocol is demonstrated by the efficient reactions involving numerous substituents ranging from electron-withdrawing groups to electron-donating groups. 相似文献
7.
AbstractA new and practical method has been developed for the synthesis of 2,4-disubstituted quinolines via one-pot three-component reaction of o-amino arylketones, aldehydes and ammonium acetate in high yields by using DDQ in CH3CN under mild conditions. Neutral conditions, atom economy, easy work-up procedures and compatible with different functional groups are the salient features of this protocol. 相似文献
8.
A series of 1,4-disubstituted 1,2,3-triazoles were synthesized through a one-pot process from easily available anti-3-aryl-2,3-dibromopropanoic acids and nitrobenzaldehydes in hexamethylphosphoric triamide. Inexpensive copper(I) iodide was the catalyst. 相似文献
9.
We demonstrated a novel, facile, high-yield, and efficient one-pot approach for the synthesis of symmetrically disubstituted ureas from isocyanates in the presence of trimethylsilanol. This novel protocol boasts the use of inexpensive reagents, operational simplicity, excellent yields of products, environmentally friendly conditions, and easy workup. To the best of our knowledge, this is the first example of the synthesis of symmetrically disubstituted ureas from isocyanates in the presence of trimethylsilanol in one pot. 相似文献
10.
Highly substituted pyridine derivatives have been accessed through an efficient, one-pot, multicomponent reaction of aldehydes, malononitrile, and ammonium acetate in the presence of triethylamine as a catalyst under solvent-free conditions. This procedure affords the desired products in high purity and has advantages such as short reaction time, excellent yields, and simple workup procedure. This procedure affords the desired products in moderate to high yields and has such advantages as short reaction time and simple workup procedure. 相似文献
11.
A facile one-pot synthesis of oxazoles 1a-h is described that utilizes readily available aromatic α-methyl ketones and a safe hypervalent iodine reagent, iodobenzene diacetate. 相似文献
12.
An efficient, convenient, high-yielding synthesis of α-amino aryl ketones is described, involving the one-pot deprotonation-transmetallation-arylation of a Weinreb amide while retaining chirality of the original amide. 相似文献
13.
Nissy Ann Harry Thomas Shilpa Sankuviruthiyil M. Ujwaldev Gopinathan Anilkumar 《Journal of heterocyclic chemistry》2021,58(1):375-381
An efficient green on-water protocol for the synthesis of 2,2-disubstituted 2,3-dihydro-1H-perimidines is demonstrated. The reaction used safer p-toluenesulfonic acid (PTSA) as a catalyst on water at 80°C, for 2 hours affording a novel method for the synthesis of various disubstituted perimidines in moderate to excellent yields. 相似文献
14.
《Green Chemistry Letters and Reviews》2013,6(4):269-273
Abstract Alum (KAl(SO4)2·12H2O) performs as a novel catalyst for the synthesis of anthraquinone derivatives from phthalic anhydride and substituted benzenes in good to excellent yields (70–96%) using water as a solvent at ambient temperature. Several solvents were examined for this reaction; however, in terms of reaction yield and time, water was found to be the optimum solvent. The remarkable advantages offered by this method are an inexpensive and easily available catalyst, a simple procedure, mild conditions, and much faster (60–120 min) reactions. 相似文献
15.
Unsymmetrically 2,5-disubstituted 1,3,4-oxadiazoles were efficiently synthesized from the cyclization-oxidation reaction of acyl hydrazones. Also, the synthesis of the title compounds was achieved by the condensation of acyl hydrazides and aromatic aldehydes in the presence of ceric ammonium nitrate in dichloromethane. 相似文献
16.
《Mendeleev Communications》2022,32(4):446-448
A new one-pot two step synthesis of unsymmetrically substituted indenes from available 3,4-diarylbutadiene sulfones involves SO2 thermal extrusion followed by acid- catalyzed cyclization of the diene formed, the cyclization proceeding selectively at the more electron-rich aryl rings. The procedure is efficient for substrates bearing donor, acceptor, as well as bulky substituents. 相似文献
17.
2,2-Disubstituted 3(2H)-furanones can be prepared readily by 1,2-addition of organometallic compounds to γ,γ-disubstituted β-bromo-α,β-butenolides followed by treatment of the adducts with acid. 相似文献
18.
Srinivasulu Ramineni Ravi Kumar Kannasani V.V. Satyanarayana Peruri 《Green Chemistry Letters and Reviews》2014,7(1):85-89
A simple and efficient method has been developed for the synthesis of benzoxazoles from 2-aminophenol and substituted aldehydes in the presence of a catalytic amount of zinc triflate in ethanol solvent at reflux temperature. 相似文献
19.
Roberto Ballini Dennis FioriniMaria Victoria Gil Alessandro PalmieriEmilio Román José Antonio Serrano 《Tetrahedron letters》2003,44(14):2795-2797
DBU catalyses the one-pot Michael addition of nitroalkanes to 1,4-dienone derivatives, elimination of nitrous acid, then intramolecular conjugate addition-ring closure to allow the direct formation of a variety of tetrahydrofurans. 相似文献