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β-羰基膦酸酯是一类重要的有机化合物和反应中间体,在有机合成及药物化学中发挥着重要的作用.提供了一种高原子经济性、高选择性、温和的炔基膦酸酯水合反应体系.实验结果表明:在阳离子金催化剂(2.5 mol%)的催化作用下,以1,2-二氯乙烷(1 m L)为溶剂,室温下炔基膦酸酯(1 mmol)与水(3 mmol)发生水合反应,高收率、高区域选择性地得到β-羰基膦酸酯化合物(收率≥92%).该方法具有底物适用范围广、反应条件温和、环境友好等优点,为含β-羰基膦酸酯结构单元的天然产物及复杂药物分子的合成提供了一种新途径. 相似文献
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利用铑(Ⅱ)催化重氮苄基膦酸酯与芳香醛或酮化学专一地进行环氧化反应,高产率、高立体选择性地合成了顺式环氧乙烷-2-膦酸酯.反应历程是重氮化合物先与醛或酮形成羰基叶立德中间体,然后发生自身环化反应.产物经红外光谱、1H核磁共振谱、质谱和X射线衍射确定结构. 相似文献
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本文报道α-砜基碳阴离子和磷酰氯的反应,提供了合成α-砜基膦酸酯和α,β-不饱和砜的新方法,此方法具有原料易得、反应步骤少、得率较高等优点.还讨论了α-芳砜基膦酸酯的质谱. 相似文献
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本文报道乙烯基膦酸酯在钯催化下的芳基化和烯基化反应,乙烯基膦酸酯与芳基溴化合物在钯催化下反应,可顺利地生成相应的E式2-芳基取代乙烯基膦酸酯(6,7).操作简便,反应条件温和,产率中平,是合成2-芳基取代乙烯基膦酸酯较好的方法.测定了不同取代芳基乙烯基膦酸二乙酯的^31P NMRδ值,它们与Hammett取代基常数σ之间有较好的线性关系.乙烯基膦酸酯亦能与烯基溴化合物反应,生成相应的取代1,3-二烯基膦酸酯(10),但反应时间较长,产率较低,由NMR推定了6,7和10的构型。 相似文献
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扼要综述了近年来关于光学活性α一羟基膦酸酯的新合成方法,介绍了有关的手性试剂和不对称反应。关键词##4光学活性;;α-羟基膦酸酯;;不对称合成 相似文献
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The reaction of the dianion of phenylsulfinylacetone with alkyl halides afforded beta-keto sulfoxides, which were first chlorinated with hexachloroethane and then treated successively with KH and t-BuLi to give carboxylic acids in three-steps in moderate overall yields from the alkyl halides. This procedure affords a good method for a synthesis of carboxylic acids from alkyl halides with three-carbon elongation. 相似文献
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Stefan Büttner Alina Bunescu Sebastian Reimann T. H. Tam Dang Thomas Pundt Renske Klassen Andreas Schmidt Nazken K. Kelzhanova Zharylkasyn A. Abilov Tariel V. Ghochikyan Ashot S. Saghiyan Alexander Villinger Helmut Reinke Anke Spannenberg Peter Langer 《Helvetica chimica acta》2013,96(1):44-58
Functionalized 5‐alkyl‐3‐(trifluoromethyl)phenols were prepared by formal [3+3] cyclization of 1,3‐bis(silyloxy)buta‐1,3‐dienes with 1,1,1‐trifluoro‐4‐(silyloxy)alk‐3‐en‐2‐ones derived from 1,1,1‐trifluoroalkane‐2,4‐diones. The latter were prepared by condensation of the dianion of 1,1,1‐trifluoropentane‐2,4‐dione with alkyl halides. 相似文献
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Substituted pyridylphenylcarbinols are formed in the reaction of the dianions of isomeric pyridyl phenyl ketones with alkyl halides, aldehydes, and benzonitrile. The reaction of the dianion of 3-pyridyl phenyl ketone with benzophenone, in contrast to the analogous reaction of the dianion of 2-pyridyl phenyl ketone, gives 5-benzoyl-2-diphenylhydroxymethyl-1,2-dihydropyridine. It is assumed that the observed reaction includes one-electron transfer and the formation of two anion radicals. Recombination of the anion radical of 3-pyridyl phenyl ketone leads to 5,5′-dibenzoyl-2,2′-di(1,2-dihydropyridyl). 相似文献
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Alex V. ShtelmanJames Y. Becker 《Tetrahedron》2011,67(6):1135-1141
New α-silylacetic acids have been prepared following a general and convenient procedure of a one-pot reaction between trimethylsilylacetate and different chlorosilanes. New derivatives of diphenyl(methyl)silylacetic acid were prepared by a direct alkylation of its dianion with benzyl-, allyl-, and alkyl halides and trimethylchlorogermane to afford new α-silylcarboxylic acids. 相似文献
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Reactions of tetrahydrofuran solutions of butadiene and acenaphthylene with alkali metal produce dianionic species which give quantitative yields of copolymers when subsequently titrated with alkyl dibromides. These polymers, however, crosslink on standing; this has been correlated with the presence of a proportion of 1,5-dihydroacenaphthylene adduct in the product.Similar reactions involving phenanthrene are not quantitative and yield materials containing only a small proportion of the phenanthrene added. The low efficiency has been attributed to the low electron affinity of phenanthrene and to the ability of its dianion to react with alkyl halides by electron transfer rather than metathetically. 相似文献
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《Tetrahedron letters》1986,27(15):1687-1690
A novel lithium allyl dianion has been generated by double deprotonation of β-alkyl (aryl) thio-dithioester. Reactions of this dianion with alkyl iodide, trimethylsilyl chloride and epoxyde occur at the γ-site. The regiochemistry of its addition to carbonyl compounds depends on the carbonyl compounds, e.g., for aldehydes ketones, α -and γ-regioselectivity respectively, were observed. The reactivity with cyclopentenone was also examined.γ-Selectivity with alkyl halides and epoxydes; γ and α-prefered selectively with respectively ketones and aldehydes. 相似文献
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A. V. Aksenov I. V. Aksenova Yu. I. Smushkevich 《Chemistry of Heterocyclic Compounds》2001,37(8):976-981
2,3'-Biquinolyl dianion reacts with organolithium and organomagnesium compounds with the formation, after treatment of the reaction mixture with water, of 2'-alkyl(aryl)-1',2'-dihydro-2,3'-biquinolyls, and, after treatment of the reaction mixture with alkyl halides, of 1'-alkyl-2'-alkyl(aryl)-1',2'-dihydro-2,3'-biquinolyls. The reaction includes attack of the nucleophilic reagent with an electron transfer to a molecule of solvent. 相似文献
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《Tetrahedron letters》1986,27(1):95-98
The rate of the reaction between the anion of 1,4-dihydro-4-methoxycarbonyl-1-methylpyridine (1− and sterically hindered alkyl halides, and between the perylene dianion (Pe2−) and t-butyl chloride and sec-butyl bromide has been measured by electrochemical techniques. The rate was found to be close to the rate of single electron-transfer (SET) from anion radicals (A⨪) with the same standard potential as 1•/1−, resp. Pe⨪/Pe2− to the corresponding alkyl halides. The kinetic results strongly suggest that a SET mechanism is the rate-determining step in these nucleophilic substitutions. 相似文献
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John W. Patterson 《Journal of heterocyclic chemistry》1986,23(6):1689-1692
The reaction of carbanions derived from Hantzsch 1,4-dihydropyridines with alkyl halides was studied and methods for mono- and di-alkylation were devised. 相似文献
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Lithium arene dianions derived of polycyclic aromatic hydrocarbons, such as naphthalene, anthracene, phenanthrene, fluoranthene, pyrene, chrysene and binaphtyl react cleanly with n-alkylfluorides to afford regiochemically controlled alkylated dihydroarenes after hydrolysis. These arene dianions can be easily prepared by simple treatment of the arene with lithium in THP. Unlike simple radical coupling, the alkylation of these species with alkyl fluorides apparently goes through a SN2 transition state, despite the inertness of alkyl fluorides to undergo nucleophilic substitution. It is also atypical for reduced arenes, which tend to give ET reactions with other alkyl halides. Prediction of the regiochemistry was easily conducted by means of MO calculations (PM3) on the dianion, and in all cases were consistent with the experimental. 相似文献