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1.
Tatiana Klimova Berestneva Marcos Martínez García Simon Hernández Ortega Elena Klimova 《Journal of organometallic chemistry》2006,691(13):2872-2882
2,3-Diferrocenyl-1-methylthiocyclopropenylium iodide reacts with water, metal alkoxides, phenolates and with alcohols in the presence of Et3N to give E-1,2-diferrocenyl-3-methylthioprop-2-enone or its ketals. Their structures were established based on data from 1H and 13C NMR spectroscopy and X-ray diffraction analysis. The mechanistic aspects of these reactions are discussed. Electrochemical properties of 8 and 13b have been studied. The compounds present two oxidation processes (I-II), attributed to the oxidations of the ferrocenes groups, E0′(I), E0′(II), ΔE0′(II-I) and comproportionation constant Kcom are reported. 相似文献
2.
The protonation processes for eight three-membered ring molecules have been investigated using the SCF LCAO MO method with Gaussian basis sets and the results are compared with those obtained at the first order approximation, i.e. the electrostatic approximation. The electrostatic results are linearly connected with the SCF ones and are sufficient to get an ordering of the protonation energies in different chemical sites and to obtain reliable representations of the proton approaching paths. 相似文献
3.
Mojca Dobnikar Marijan Kočevar Andrej Petrič Miha Tišler Bojan Verček 《Monatshefte für Chemie / Chemical Monthly》1989,120(3):269-272
Summary Syntheses of 1-methylimidazo[1,2-c]quinazolinium iodide (3) and 1-methylimidazo[2,1-f]pyrido[3,2-d]pyrimidinium iodide (4) are described. These tricyclic compounds react with nucleophiles derived from active methylene compounds to give the corresponding open-chain enamines.
Reaktionen von quaternisierten Imidazo-Chinazolinen und -Pyridopyrimidinen mit Verbindungen mit reaktiven Methylengruppen
Zusammenfassung Synthesen von 1-Methylimidazo[1,2-c]chinazoliniumjodid (3) und 1-Methylimidazo[2,1-f]pyrido[3,2-d]pyrimidiniumjodid (4) werden beschrieben. Diese tricyclischen Verbindungen reagieren mit einigen Carbanionen aus Verbindungen mit reaktiven Methylengruppen, wobei die offenkettigen Enamine entstehen.相似文献
4.
In the presence of one equivalent of boron trifluoride etherate, organolithium compounds cause the ring cleavage reactions of tetrahydrofurans and tetrahydropyran to give the corresponding long-chain alcohols in moderate yields. These reactions are highly regioselective for unsymmetric cyclic ethers. 相似文献
5.
Aziridines and epoxides were reacted with diphenyl diselenide in the presence of a stoichiometric amount of (n-Bu)3P, respectively, giving β-amino- or β-hydroxy selenides in moderate to excellent yields under mild conditions. In the reactions the (n-Bu)3P might act as a reductant though it was a nucleophilic catalyst in other similar ring-opening reactions. 相似文献
6.
Reactions of phenyllithium with LiAlH4 in diethyl ether have been studied in detail. Lithium hydride, as an insoluble solid, and LiAlPhn H4?n (where n = 2 or 3)_in solution, are formed when the PhLi to LiAlH4 ratio is 2/1and 3/1. However, Li3AlH6 is formed when LiAlH4 is added to an equimolar solution of PhLi in diethyl ether. The integrity of the products have been established by IR, NMR and X-ray powder diffraction pattern. 相似文献
7.
Stefan Kwiatkowski Andrzej Wolinski 《Monatshefte für Chemie / Chemical Monthly》1984,115(6-7):869-872
Reaction of 1,3-dioxolanes and 1,3-dioxanes with aliphatic acid chlorides and bromides yields 2- or 3-halohydrine esters.
Reaktionen von 1,3-Dioxacyclanen mit Säurehalogeniden. Eine neue Synthese für -Halogenhydrinester (Kurze Mitteilung)
Zusammenfassung Die Reaktion von 1,3-Dioxolanen und 1,3-Dioxanen mit aliphatischen Säurechloriden ergab 2- bzw. 3-Halogenhydrinester相似文献
8.
非对称环氧乙烷的区域选择性亲核开环反应 总被引:4,自引:0,他引:4
本文总结了常用亲核试剂对非对称环氧乙烷的亲核开环反应及其区域选择性。强亲核性的亲核试剂通常只受空间效应影响,进攻非对称环氧乙烷位阻小的碳原子,对于烯基取代环氧乙烷还可以进攻烯基的β-碳原子发生SN2'开环反应,其他亲核试剂同时受空间效应和电子效应的影响,对于烷基环氧乙烷通常进攻其取代少的碳原子, 空间效应起主导作用,而对芳基和烯基取代环氧乙烷开环反应通常发生在环氧乙烷芳甲位和烯丙位的碳原子上, 电子效应起主导作用。在质子酸或强Lewis酸存在下,虽然单烷基环氧乙烷的开环仍然发生在其取代少的碳原子上,但对于芳基、烯基和同碳双取代环氧乙烷,亲核开环反应将主要受电子效应控制,一般亲核试剂倾向于进攻环氧乙烷的芳甲位、烯丙位或多取代的碳原子。分子内的亲核开环反应主要受成环时环大小的控制, 成环时的倾向是五元环> 六元环> 七元环。环氧乙烷亲核开环的区域选择性是环氧乙烷和亲核试剂空间效应和电子效应平衡的结果。 相似文献
9.
环硫乙烷与它的氧类似物环氧乙烷和氮类似物氮杂环丙烷一样,是一类重要的有机合成中间体,在医药和农用化学品工业领域也得到广泛应用。通过开环和异构化反应,还广泛用于制备硫醇和硫醚等含硫化合物。本文总结了常用亲核试剂对非对称环硫乙烷的亲核开环反应及其区域选择性。环硫乙烷的亲核开环反应通常只受空间效应影响,亲核试剂进攻非对称环硫乙烷位阻小的碳原子,对于烯基取代的环硫乙烷有时可以进攻烯基的β碳原子发生SN2’开环反应。强亲核性的亲核试剂容易致使环硫乙烷脱硫生成烯烃,而亲核性相对较弱的亲核试剂容易发生多聚反应生成多硫醚。在Lewis酸存在下,电子效应会对开环反应的区域选择性产生影响,甚至起主导作用。虽然烷基取代环硫乙烷在Lewis酸存在下的开环仍然主要发生在其取代基少的碳原子上(位阻控制),但受电子效应影响,芳基和烯基取代环硫乙烷的亲核开环,其亲核试剂一般倾向于进攻环硫乙烷的芳甲位和烯丙位碳原子(电子效应控制)。 相似文献
10.
综述了近年来过渡金属不对称催化氧杂苯并降冰片烯开环反应的研究进展, 包括钯催化、镍催化、铜催化和铑催化四部分内容, 并对部分反应的机理进行了介绍. 相似文献
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O. A. Sof''ina N. M. Igidov E. N. Koz''minykh N. N. Trapeznikova Yu. S. Kasatkina V. O. Koz''minykh 《Russian Journal of Organic Chemistry》2001,37(7):1017-1025
Acylpyruvic acids readily react with 2,3-diaminopyridine to form (Z)-3-acylmethylene-1H-3,4-di- hydropyrido[2,3-b]pyrazin-2-ones. 5-Aryl-2,3-dihydrofuran-2,3-diones which can be regarded as lactones derived from -enolized aroylpyruvic acids react with 2,3-diaminopyridine under mild conditions, yielding regioisomeric (Z)-2-aroylmethylene-4H-1,2-dihydropyrido[2,3-b]pyrazin-3-ones. The structure of the products and reaction chemoselectivity are discussed. 相似文献
15.
Dr. Lara Mata Prof. Alberto Avenoza Dr. Jesús H. Busto Prof. Jesús M. Peregrina 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(21):6831-6839
Although 1,2‐cyclic sulfamidates derived from α‐methylisoserine undergo nucleophilic displacement at the quaternary center, to the best of our knowledge their behavior with amines as nucleophiles has never been explored. We have found that a broad range of amines can be used, demonstrating the scope of the reaction, and that excellent control of the chemoselectivity can be achieved. Application of this methodology for the synthesis of a chiral α,β‐diamino acid and an important piperazinone heterocycle is also presented. Additionally, we have found that DMF and DMSO behave not only as polar aprotic solvents but also as O‐nucleophilic reagents, allowing the incorporation of an oxygen atom at a quaternary center of the electrophile, with inversion of configuration. 相似文献
16.
Long Yuhua Yang Dingqiao Zeng Heping Xie Lei Wu Lihuan Mo Haihong Zuo Xiongjun 《中国化学》2010,28(2):235-242
Asymmetric ring‐opening reactions of N‐Boc‐azabenzonorbornadiene with N‐substituted piperazine nucleophiles in the presence of 5 mol% of [Rh(COD)Cl]2 and 10 mol% of chiral ligand, (R,S)‐PPF‐P‐t‐Bu2, gave the corresponding 1,2‐diamine product in moderate to excellent yields (up to 95%) with reasonable enantiomeric excesses (up to 70% ee). The results showed that the nature of ligands had significant influence on the yields and the enantiomeric excesses. 相似文献
17.
2-Ethoxycarbonyl-5,6,7,8-tetrafluorochromone reacts with methylamine differently, depending on the solvent nature and the
amount of the amine: in DMSO and MeCN, the fluorine atom at the C(7) atom is initially replaced and then the C(2) and/or C(9)
are attacked, while in ethanol, the reaction involves the C(2) atom with opening of the pyrone ring. The reaction of 3-ethoxycarbonyl-5,6,7,8-tetrafluoro-2-methylchromone
with methylamine results, regardless of the solvent, in opening of the chromone ring and the formation of intermediate ethyl
3-(3,4,5,6-tetrafluoro-2-hydroxyphenyl)-2-(1-methylamino)ethylidene-3-oxopropionate, which undergoes intramolecular cyclization
to give 5,6,7,8-tetrafluoro-3-(1-methyl-amino)ethylidene-3,4-dihydro-2H-benzopyran-2,4-dione.
Dedicated to Academician N. S. Zefirov on the occasion of his 70th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2093–2098, September, 2005. 相似文献
18.
Martín-Rapún R Fan X Sayalero S Bahramnejad M Cuevas F Pericàs MA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(32):8780-8783
Lighten the load! A family of enantiopure 4-oxy-substituted 3-aminopyrrolidines arising from the enantioselective ring-opening of meso-3-pyrroline oxide have been developed as catalysts for the asymmetric, anti-selective Mannich reaction (see scheme; PMP=p-methoxyphenyl; PG=protecting group). Very high catalytic activity (down to 0.01 mol?% loading) and stereoselectivity have been recorded. 相似文献
19.
V. R. Sinyakov Ya. V. Zonov V. M. Karpov I. V. Beregovaya V. E. Platonov 《Russian Journal of Organic Chemistry》2013,49(7):1010-1018
Reactions of perfluorobenzocycloalkenes (ArFF) with methyllithium and ethyl cyanoacetate involved replacement of fluorine atoms in positions 3 and 4 of perfluorocyclobutabenzene, position 5 of perfluoroindan, and position 6 of perfluorotetralin by CH3 and CH(CN)COOEt groups. Hydrolysis of the resulting esters ArFCH(CN)COOEt gave the corresponding perfluoroarylacetic acids ArFCH2COOH which were converted into dichloroacetyl chlorides ArFCCl2COCl by treatment with PCl5. The reaction of ArFCCl2COCl with SbF5 produced trifluoromethyl derivatives ArFCF3. Decarboxylation of ArFCCl2COOH in DMF afforded dichloromethyl derivatives ArFCCl2H which reacted with CsF on heating to form difluoromethyl analogs ArFCF2H. 相似文献
20.
Highly Enantioselective Ring‐Opening Reactions of Aziridines with Indole and Its Application in the Building of C3‐Halogenated Pyrroloindolines 下载免费PDF全文
Fengxia Han Dan Li Dr. Depeng Zhao Dr. Yiming Cao Yunxia Ma Weidong Kong Quantao Sun Prof. Dr. Rui Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(50):16478-16483
A magnesium‐catalyzed asymmetric ring‐opening reaction of aziridine with indole has been realized by employing commercially available chiral ligands. Both of the enantiomers of the ring‐opening product could be obtained with good yields and a high level of enantioselectivity. The corresponding ring‐opening product could be further transformed to various types of enantioenriched C3‐halogenated‐pyrroloindolines. 相似文献