共查询到20条相似文献,搜索用时 15 毫秒
1.
Efficient synthesis of a variety of 3-substituted coumarins via NaOMe-catalyzed Knoevenagel condensation and one-pot preparation of 3,4-unsubstituted coumarins in the presence of NaOMe via Wittig reaction in room-temperature ionic liquids are described. Knoevenagel condensation of 2-hydroxybenzaldehyde with dimethyl- and diethylmalonate was performed with excellent yields in room-temperature ionic liquids. Although diethyl- and dimethylchloromalonates were mostly recovered unchanged in Knoevenagel condensation, higher conversions were observed via Wittig reaction of these compounds with 2-hydroxybenzaldehyde derivatives and triphenylphosphine. Other 2-hydroxybenzaldehyde derivatives, methyl- and ethylchloroacetates, were reacted in ionic liquids to afford simple coumarins in good yields. These reactions widen the applicability of ionic liquid in organic synthesis. 相似文献
2.
Reaction of cyclic sulfates of vic-diols with magnesium iodide in acetonitrile produced the corresponding olefins in excellent isolated yields at room temperature. Cyclic sulfates of trans-diols gave trans-alkenes exclusively. Cyclic sulfates of cis-diols gave a mixture of cis- and trans- alkenes. However, the cyclic sulfate of cyclic cis-diol afforded the corresponding cis-alkene only. 相似文献
3.
A convenient general synthesis of 2,2-dimethyl-3,4-dihydro-2H-pyrano[2,3-b]quinolines using the Wittig reaction is described. The o-nitrobenzaldehydes (1a–d) on reaction with phosphorane 2 provided ( E )-ethyl-α-(2,2-dimethylprop-2-ene)-2-nitrocinnamates (3a–d) in excellent yields, which on cyclization with polyphosphoric acid followed by reductive cyclization using Fe/HCl afforded dihydropyranoquinolines (5a–d). Alternatively, the pyranoquinolines 5a–d were also synthesised from esters 3a–d by employing domino reductive cyclization in a single step. 相似文献
4.
Abbas Shockravi Hassan Valizadeh Majid M. Heravi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3):501-504
An efficient and facile preparation of simple coumarins via in situ Wittig reaction of salicylaldehydes, triphenylphosphine, and chloroethylacetate supported on MgO in satisfactory yields in solvent-free condition. 相似文献
5.
由二苯甲酮合成二苯甲硫酮,再使它与月佳烯发生环加成反应,合成了两种不饱和环状硫醚,总产率74.6%。 相似文献
6.
A convenient and environmentally-friendly synthetic method of olefins via deacylation reaction is described. The reaction gives olefins by condensation of aldehydes with a variety of 1,3-dicarbonyl compounds in the presence of anhydrous potassium carbonate at room temperature in high yields (70-90%) in one step. The synthetic potential of this strategy can be used as an alternative procedure to the Wittig, Wittig-Horner reactions. The stereochemistry of the resulted olefins was determined by NOE experiment with correct radio frequency and X-ray analysis. The E/Z selectivity of the deacylation reaction depends on the α-substituents of the 1,3-dicarbonyl compounds. 相似文献
7.
8.
以邻氨基苯酚和对甲基苯甲酸为原料,多聚磷酸为溶剂,N2保护下于220 ℃反应制得中间体L1; L1溴代得中间体L2; L2与三苯基膦反应得膦盐L3,L3与吡啶-3-甲醛通过Wittig反应制得中间体L4,再通过甲基化反应和阴离子置换合成了未见报导的化合物1~6,并利用1H NMR, 13C NMR, FT-IR和HR-MS对化合物1~6的结构进行了表征。单晶结构测试表明:化合物1(CCDC: 1838541)的阳离子部分的平面性较好。紫外可见吸收光谱和荧光发射光谱结果表明:化合物1~6在不同极性溶剂中均具有良好的光学性质。 相似文献
9.
Interaction of α,ω-dihaloalkanes with sulfide ion (eq. 1) is a common route for the synthesis in good yield of 5- and 6-membered polymethylene sulfides. 相似文献
10.
An improved method for the large scale preparation of N, N'-disuccinimidyl carbonate from triphosgene and N-hydroxy-succinimide has been developed. 相似文献
11.
12.
Organocatalytic inter- and intramolecular [4+2] and [3+3] cycloadditions of α,β-unsaturated aldehydes to give polysubstituted aromatic aldehydes are described. High periselectivity for the cycloadditions, with catalyst effects exerted by l-proline and pyrrolidine-HOAc, as well as cocatalyst, additive effects, has been observed. 相似文献
13.
In a system of ammonium acetate and acetic acid under microwave irradiation, N‐phenacylpyridinium chloride 1 reacted with 2 mol of aromatic aldehydes 2a–h to give 2,4,6‐triarylpyrimidine 3a–h, reacted with pyridinecarboxaldehyde 4a–c and acetophenone 5 to yield bipyridine derivatives 6a–c. The structure of the products was characterized with 1H NMR, 13C NMR, IR, and mass spectroscopy. 相似文献
14.
An alternative synthesis of monosubstituted ferrocenylheterocyclic compounds, using impure bis(tributylstannyl)ferrocene and heterocyclic bromides as substrates through Pd-catalyzed selective Stille coupling reaction and subsequent destannylation, is described. 相似文献
15.
Diketopyrrolo[3,4-c]pyrroles (DPP) are high-performance organic optoelectronic materials. They have applications in solar cells, fluorescent probes, bioimaging, photodynamic/photothermal therapy, and in many other areas. This article reports a convenient two-step synthesis of various DPP dyes from Pigment Red 254, an inexpensive commercial pigment. The synthesis includes a Suzuki–Miyaura cross-coupling reaction of a bis(4-chlorophenyl)DPP derivative with aryl and hetaryl boronic acids under mild reaction conditions. The new dyes show large Stokes shifts and high fluorescence quantum yields, important features for their potential use in technical and biological applications. 相似文献
16.
Studies on the Synthesis of Penazetidine A, an Alkaloid Inhibitor of Protein Kinase C 总被引:1,自引:0,他引:1
ZhiMingLI BingWANG FengGangTAO GuoQiangLIN 《中国化学快报》2004,15(2):138-140
A convergent asymmetric synthesis of (2S, 3R, 4S, 12′R)-3-hydroxy-2-hydroxymethyl-4-(12′-methyloctadecyl)-N-(p-tolylsulfonyl)-azetidine, a key precursor of penazetidine A, has been achieved by starting from divinylcarbinol. 相似文献
17.
Despite recent advances in the use of alkyl azides in ring expansion reactions of ketones, there has been little work done on the corresponding chemistry of aldehydes. In the present study, the Lewis acid-promoted reactions of alkyl azides with aldehydes were studied in both intermolecular and intramolecular contexts. The intramolecular reactions of azidoalkyl aldehydes in which the azide and carbonyl groups were separated by 2-5 carbons were examined. Although the examples having the shortest tether failed (3-azidopropanals), each of the other systems gave good yields of either NH-substituted lactams (resulting from hydride migration in the initially formed azidohydrin adduct) or formamides (alkyl migration). The product formed was dependent on the chain length of the starting azido aldehyde. The intermolecular reactions were less efficient, requiring TiCl4 promotion for even moderate yields, and in each case gave mixtures of products resulting from hydride and alkyl migration. 相似文献
18.
A. G. Korepin P. V. Galkin N. I. Golovina L. O. Atovmyan L. T. Eremenko 《Russian Chemical Bulletin》1992,41(3):582-583
Hydrogen fluoride was eliminated from N,C-difluorinated derivatives of bis(polynitroalkyl)amines by the action of alkanols. Previously unreported -fluoropolynitroalkylaldimines were obtained.Institute of Chemical Physics, Russian Academy of Sciences, 142432 Chernogolovka. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 742–743, March, 1992. 相似文献
19.
20.
Phebaclavin A (1) and C (2) were synthesized in 60% and 58% total yields over 5 steps from commercially available starting meterials respectively. The synthesis feature was usage of the Wittig reaction twice and solvent-free cyclizing reaction as the key steps. 相似文献