共查询到19条相似文献,搜索用时 187 毫秒
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本文报道稳定胂叶立德与异氰酸苯酯反应时,在胂叶立德的亚甲基碳原子上发生N-苯胺甲酰化,并得到相应的稳定双羰基胂叶立德.经元素分析,IR和^1HNMR鉴定,确证了产物的结构. 相似文献
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利用温室气体二氧化碳(CO2)与环氧化合物共聚制备具有生物可降解性的脂肪族聚碳酸酯是近年来聚合物科学领域的研究热点之一。其中最受关注的是CO2和环氧丙烷(PO)的交替共聚物-聚碳酸亚丙酯(PPC)。由于PPC的分子间作用力比较弱,致使其热性能和力学性能较差,限制了其规模化生产与应用。三元共聚、嵌段共聚、接枝、扩链、交联和封端等化学方法是调控PPC链结构进而改善其性能的最直接最有效途径。本文对这一研究领域的进展情况进行了综述,探讨了化学改性过程中面临的挑战和问题,指出了未来发展的新趋势,以期促进PPC的开发和应用。 相似文献
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Fluorescein ethyl ester as a model and four dyads of Fluorescein and Anthroic acid linked with different length spacer were synthesized and characterized. They were put in bilayer membrane and on SnO2 coated substrate, The photoinduced voltaic responses were observed and compared when fluorescein was excited using visible light. It was found that the dyads have higher responses than the model, and the dyad with a butylene spacer (n=4) has the highest response. The results and related mechanisms were discussed. 相似文献
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Sodium dialkyl phosphite reacts with non-activated alkyl halide in the presence of crown ether to give dialkyl alkyl phosphonate in moderate yield. Little or no reaction takes place in the absence of crown ether under the same conditions. In all cases, crown ether was present in catalytic amts. indicating that it behaves as a phase transfer catalyst between solid and liquid phases. The influences of structures of crown ethers, alkyl halides, dialkyl phosphites and the nature of solvent on the P-alkylation of sodium dialkyl phosphite have been investigated. 相似文献
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A new “task-specific” ionic liquid (TSIL), 1-n-butyl-3-methylimidazolium thiocyanate ([bmim]SCN), has been prepared and used for the first time as the medium as well as reactant for the synthesis of alkyl thiocyanates from the corresponding alkyl halides by thiocyanate-halide exchange at room temperature. The alkyl thiocyanate products can be easily isolated from the reaction mixture by simple extraction and the ionic liquid 1-n-butyl-3-methylimidazolium halide may be reused for the synthesis of the ionic liquid [bmim]SCN and recycled for further use. 相似文献
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Alkylation of 1,2,4,5-tetrahydro-3-methyl-3H-3-benzazepin-2-one 1a with various halides and sodium hydride in tetrahydrofuran-dimethylformamide solvent system was studied. Primary halides predominantly provided the 1-mono-substituted products, such as alkyl (2a-g, p, q), allyl (2j, k), propargyl (21) and benzyl (2m-o) derivatives, in satisfactory yields, and secondary halides resulted in lower yields (2h, i) than primary halides. In attempted dialkylations with ω, ω'-dibromoalkanes, 5- and 6-membered spiro products (4c, d) were obtained by this method. The Michael type addition reaction was also studied and it was found that acrylic acid esters gave the corresponding adducts (2p, q). 相似文献
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Ankita Chakraborty Sudipto Debnath Tanmoy Ghosh Dilip K. Maiti Swapan Majumdar 《Tetrahedron》2018,74(40):5932-5941
A sustainable route for the N-1 alkylation of imidazole and benzimidazole derivatives has been developed under volatile organic solvent free condition in alkaline water-SDS system. Incorporation of SDS in the reaction medium enhances the reaction rate by suppressing the solubility issue that arises for different substrates. This method provides high yield of the alkylated product in a shorter reaction time. For reactive alkyl halides reaction proceeds at ambient temperature whereas in the cases of less reactive alkyl halides require 55–60?°C to complete alkylation process. N-alkylation induced ring opening of the heterocyclic ring in benzimidazole derivatives to multifunctional aromatic compounds were noticed at 60?°C when more than two equivalents of alkyl halide was used. 相似文献
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The alkylation of alkyl phosphinates and some H-phosphonate diesters is promoted by the base DBU. Only more reactive alkyl halides react in preparatively useful yields. However, the method provides easy access to important H-phosphinate building blocks, without the need for a protecting group strategy or metal catalysts. The reaction is conveniently conducted at, or below, room temperature. The preparation of methyl-H-phosphinate esters is particularly interesting as it avoids the heretofore more common use of methyldichlorophosphine MePCl2. 相似文献
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Rapid and convenient methods are described for the exhaustive derivatization of carbonyl, carboxyl and hydroxyl groups of prostaglandins and related compounds to methoxime, alkyl ester and alkyl ether compounds respectively. Optimal reaction conditions were established for each group. The reactions were carried out in polar aprotic solvents. Alkyl ester alkyl ether derivatives were obtained quantitatively and rapidly in one step with n-alkyl (C1-C4) halides in the presence of sodium hydroxide. Methyl ester methyl ether derivatives have the highest volatility, but propyl ester propyl ether derivatives improved the separation of complex mixtures. The carbonyl group sometimes induced side-products, so the carbonyl group was converted into methoxime. Methoximation was achieved quantitatively by using methoxylamine in the presence of hydrochloric acid or sodium hydroxide, followed by alkylation in same reaction medium. Methoximation gave syn- and anti-isomers, which were separated chromatographically, decreasing the resolution for complex samples. 相似文献
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N-Heterocyclic carbene-catalyzed umpolung of aldehydes followed by their interception with diarylbromomethanes has been reported. This conceptually novel transition-metal-free cross-coupling of aldehydes with alkyl halides works well at low catalyst loadings and under mild reaction conditions leading to the formation of diaryl acetophenone derivatives in good yields. In addition, α-halo ketones and esters can also be used as aldehyde reaction partners. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(12):3367-3371
Suzuki, Negishi, and Kumada couplings are some of the most important reactions for the formation of skeletal C−C linkages. Their widespread use to forge bonds between two aromatic rings has enabled every branch of chemical science. The analogous union between alkyl halides and metallated aryl systems has not been as widely employed due to the lack of commercially available halide building blocks. Redox‐active esters have recently emerged as useful surrogates for alkyl halides in cross‐coupling chemistry. Such esters are easily accessible through reactions between ubiquitous carboxylic acids and coupling agents widely used in amide bond formation. This article features an amalgamation of in‐house experience bolstered by approximately 200 systematically designed experiments to accelerate the selection of ideal reaction conditions and activating agents for the cross‐coupling of primary, secondary, and tertiary alkyl carboxylic acids with both aryl and heteroaryl organometallic species. 相似文献
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[reaction: see text] A one-pot protocol for converting 1,3- and 1,4-substituted aryl halides to arylamine boronate esters is described. This is achieved by sequential Ir-catalyzed aromatic borylation at the least hindered C-H bond of the aryl halide and subsequent Pd-catalyzed C-N coupling at the halide position of the crude arylboronic ester. 相似文献
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A novel, convenient, and efficient approach to the synthesis of penta-substituted pyrroles has been reported based on the multicomponent reaction. Solvent-free condition for the formation of enaminones from primary amines and alkyl acetoacetates and it's reaction with fumaryl chloride lead to the formation of pyrroles that have halide, CH2CO2H, ester functional groups, and two alkyl substitutions. 相似文献