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1.
Quantum-chemical calculations using the semiempirical AM1/COSMO method have shown that the regioselectivity of [2+3] cycloaddition
of 3-nitro-1-propene to triphenylnitrone is a function of thermodynamic factors.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp.913–917, June, 2008. 相似文献
2.
We describe the synthesis of a series of conformationally constrained nicotine analogues 2-5 from appropriate pyridine-containing enals, featuring an intramolecular azomethine ylide-alkene [3+2] cycloaddition. The objective of the current project is to develop new selective nAChRs-targeting ligands. Of the nicotine analogues that we have studied, the conformation-restricting ring B unit can be either a five-membered carbocycle, or a six-membered carbocycle or heterocycle. The present work constitutes a general method for rapid assembly of other related tricyclic nicotine analogues. 相似文献
3.
Fernanda M. Ribeiro Laia 《Tetrahedron letters》2009,50(45):6180-2356
The reactivity of buta-2,3-dienoates toward aziridines is reported. Allenoates react as 2π-component in the [3+2] cycloaddition with the azomethine ylide generated from cis-1-benzyl-2-benzoyl-3-phenylaziridine affording 4-methylenepyrrolidines in a site-, regio-, and stereoselective fashion. Under conventional thermolysis, cis- and trans-2-benzoyl-1-cyclohexyl-3-phenylaziridines showed a different reactivity. These aziridines participate in formal [3+2] cycloadditions with allenes via C-N bond cleavage of the three-membered ring leading to functionalized pyrroles. 相似文献
4.
Shū Kobayashi Ryoji HirabayashiHaruka Shimizu Haruro IshitaniYasuhiro Yamashita 《Tetrahedron letters》2003,44(16):3351-3354
[3+2] Cycloaddition between hydrazones and olefins was accelerated in the presence of a stoichiometric amount of BF3·OEt2 or a catalytic amount of Zr(OTf)4, Hf(OTf)4, or Sc(OTf)3 under mild conditions. The corresponding pyrazolidine derivatives were obtained in moderate to high yields using this novel [3+2] Lewis acid catalysis. 相似文献
5.
Beatriz Lantaño Esteban Ariel Ugliarolo Graciela Yolanda Moltrasio 《Tetrahedron》2008,64(18):4090-4102
We report the single step synthesis of several 3-arylindanes and related compounds via a formal [3+2] cycloaddition. A study of the influence of the aromatic ring substitution pattern on the reaction was carried out. 相似文献
6.
Sylvain Celanire Frederic Marlin Jack E. Baldwin Robert M. Adlington 《Tetrahedron》2005,61(12):3025-3032
The synthesis of 3,11-dioxatricyclo[5.3.1.01,5]undeca-5,9-dien-8-ones is reported from suitable 5-substituted furfuryl alcohols bearing an acetylenic side-chain. Successive peracid-mediated oxidative rearrangement of furan carbinols and base-assisted intramolecular 1,3-dipolar cycloaddition afforded oxygen-bridged tricyclo-undecane derivatives. Stereoselective transformations of cycloadducts are also discussed. 相似文献
7.
A novel synthesis to camptothecin is described. A Friedlander condensation of o-aminobenzaldehye 2 with tricylclic ketone 3 affords camptothecin after further elaboration. Tricyclic ketone 3 is prepared via a route employing a [3+2] nitrone cycloaddition and an intramolecular Knoevenagel condensation. 相似文献
8.
Shota Nagasaki 《Tetrahedron letters》2008,49(22):3578-3581
[2+2] Cycloaddition reactions of P2 with alkenes were predicted to have concerted paths, that is, pseudoexcitation, distorted 2πs+2πs, and 2πs+2πa processes without any interventions of intermediates. The pseudoexcitation and/or distorted 2πs+2πs paths with retention of configuration of alkenes are kinetically preferred to the 2πs+2πa path with inversion of configuration. The reactions were predicted from the appreciable difference in the calculated enthalpies of activation to be stereospecific. 相似文献
9.
Methylenecyclopropanes react with activated aldehydes or ketones in the presence of various Lewis acids to give the corresponding [3+2] cycloaddition products having tetrahydrofuran (THF) skeleton in good yields and in some cases with high stereoselectivity. 相似文献
10.
A model study toward total synthesis of madreporanone, a novel diterpene isolated from Azorella madreporica, was investigated. The [3.3.0] bicyclic core of madreporanone bearing a cis-configured isopropyl group and two vicinal quaternary carbon centers was stereoselectively constructed via an intramolecular Rh-catalyzed [3 + 2] cycloaddition in a single step. 相似文献
11.
The synthesis of a phosphoramidite reagent for 5′-modification of oligonucleotides by introducing an arylacetylene residue
has been described. Using the reaction with 3-(perylen-3-yl)propyl azide as an example, it was shown that the acetylene derivatives
of oligonucleotides synthesized using this reagent undergo CuI-catalyzed [3+2] dipolar cycloaddition. Fluorescent conjugates were obtained in high yields and characterized by mass spectra.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1220–1226, July, 2006. 相似文献
12.
《Comptes Rendus Chimie》2016,19(3):306-313
A simple, mild and efficient method is developed for the synthesis of 5-substituted 1H-tetrazoles. Out of three used Pb(II) catalysts, lead chloride (PbCl2) has been found to be an efficient catalyst for [3+2] cycloaddition of NaN3 with aromatic and aliphatic nitriles to afford 5-substituted 1H-tetrazoles. The catalyst is reusable up to four cycles with consistent activity. The cost effectiveness and easy availability of the catalyst, simple methodology, excellent yield and easy work-up are the additional advantages. 相似文献
13.
Didier Bérard 《Tetrahedron letters》2007,48(46):8238-8241
Treatment of various substituted phenols in the presence of furan, iodobenzene diacetate, and trifluoroethanol promotes oxidative formal [2+3] cycloaddition in moderate to useful yields. 相似文献
14.
A. V. Varlamov A. I. Chernyshev F. I. Zubkov K. F. Turchin A. N. Levov 《Chemistry of Heterocyclic Compounds》2004,40(3):364-369
The cycloaddition of methyl acrylate and ethyl acrylate to 4,5-dihydro-5-methyl-3H-spiro[benz-2-azepine-3,1'-cyclohexane] N-oxide proceeds without either regiospecificity or stereospecificity. Eight geometrical isomers of spiro[isoxazolidino[3,2-a]benz-2-azepine-5,1'-cyclohexane] were formed, of which several were isolated as pure samples. The cycloaddition of dimethyl acetylenedicarboxylate proceeds stereoselectively, leading to spiro[isoxazolino[3,2-a]benz-2-azepine-5,1'-cyclohexane] with cis arrangement of the protons at C(7) and C(11b). 相似文献
15.
以吲哚-3-丙酸和吲哚-3-丁酸为原料,分别与炔丙胺发生缩合反应得到3-(丙酰丙炔胺)吲哚(4a)和3-(丁酰丙炔胺)吲哚(4b),然后4a和4b分别与9-(叠氮基乙基氨基)-1,2,3,4-四氢吖啶类衍生物5a~5c在微波辐射下发生Husigen[3+2]环加成反应得到12个新型乙酰胆碱酯酶抑制剂——他克林-吲哚杂二联体,其结构经NMR,IR和HRMS表征.初步生物活性测试表明,目标化合物均具有较强的乙酰胆碱酯酶抑制能力,其中化合物2b和2d抑制鱼鳐乙酰胆碱酯酶的IC50值分别为1.6和2.0 nmol.L-1,是6T6BA(IC50=11.0 nmol.L-1,鱼鳐)的6.9和5.5倍. 相似文献
16.
J. Paul Raj D. Gangaprasad K. Karthikeyan R. Rengasamy M. Kesavan M. Venkateswarulu M. Vajjiravel J. Elangovan 《Tetrahedron letters》2018,59(51):4462-4465
A collection of 3,5-disubstituted pyrazoles are constructed by the oxidative [3+2] cycloaddition of electron deficient terminal olefins with α-diazoesters and amides in the presence of Oxone and cetyltrimethyl ammonium bromide. The highlights of this protocol are; (i) shorter reaction time (ii) moderate to excellent yield (iii) good regioselectivity. 相似文献
17.
18.
Pengcheng Wang Ruirui Yu Sajjad Ali Zhengshen Wang Zhigang Liu Jinming Gao Huaiji Zheng 《Molecules (Basel, Switzerland)》2021,26(10)
As an important moiety in natural products, N,O-acetal has attracted wide attention in the past few years. An efficient method to construct N,O-acetal has been developed. Using silver catalyst, cyclobutenediones were smoothly converted to the corresponding γ-aminobutenolides in the presence of formamides, in which cyclobutenediones likely proceed with a key decarbonylative [3 + 2] cycloaddition process. In this way, a series of products with varied substituents were isolated in moderate yield and fully characterized. 相似文献
19.
Bing-Feng Sun Chao-Lei Wang Rui DingJin-Yi Xu Guo-Qiang Lin 《Tetrahedron letters》2011,52(17):2155-2158
A concise enantioselective synthesis of diversely functionalized advanced intermediates comprising the tricyclic skeleton of englerin A and related oxygen-bridged guaianes has been successfully accomplished, which features a Harmata organocatalytic [4+3] cycloaddition reaction. 相似文献
20.
Jianwu Xie 《Tetrahedron letters》2008,49(48):6910-6913
A chiral thiourea catalyst possessing an amine function catalyzes an asymmetric [3+2] cycloaddition of azomethine ylides to nitroolefins to provide highly functionalized pyrrolidines with high diastereo- and enantioselectivities (up to 98:1:1 dr, 92% ee). The reaction proceeds in a stepwise manner consisting of Michael addition and subsequent intramolecular aza-Henry reaction. Both reactions are promoted by the thiourea catalyst, and the reaction rate of the latter step is efficiently enhanced by the addition of 2,2,2-trifluoroethanol. 相似文献