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1.
A new catalytic system for enantioselective [2+2]-cycloaddition reaction of 2-methoxycarbonyl-2-cyclopenten-1-one with thioacetylene derivatives is described. The use of a catalytic amount (20-30 mol%) of copper(II) salt with chiral bis-pyridine ligand was found to be effective in promoting the [2+2]-cycloaddition reaction, furnishing the corresponding bicyclic compound in good yield and good enantioselectivity. 相似文献
2.
N. A. Keiko T. A. Kuznetsova L. I. Larina Yu. A. Chuvashev T. A. Klepikova L. V. Sherstyannikova 《Russian Journal of Organic Chemistry》2006,42(10):1421-1425
Conditions were found for the preparation of 2-ethoxyprop-2-enal dimethylhydrazone by reaction of 2-ethoxypropenal with N,N-dimethylhydrazine. 2-Ethoxyprop-2-enal dimethylhydrazone reacted with methyl vinyl ketone and methyl acrylate according to the [4 + 2]-cycloaddition pattern with regioselective formation of substituted tetrahydropyridines. The major product in the reaction of 2-ethoxyprop-2-enal dimethylhydrazone with 1,4-benzoquinone was 5-hydroxy-1-benzofuran-2-carbaldehyde dimethylhydrazone formed as a result of [3 + 2]-cycloaddition; a small amount of the corresponding [4 + 2]-cycloaddition product was also obtained. Some spontaneous transformations of the primary cycloaddition products were revealed. 相似文献
3.
A. F. Khlebnikov M. S. Novikov R. R. Kostikov 《Chemistry of Heterocyclic Compounds》1987,23(10):1070-1076
Ketenimine-ylides Ph2C=C-N+(=CCl2)Ar, formed by the reaction of N-(2,2-diphenylvinylidene)anilines with dichlorocarbene, generated by heating sodium trichloroacetate in chloroform, undergoes [2+3]-cycloaddition with dimethylacetylenedicarboxylate, methyl methacrylate, and dimethyl fumarate to give pyrrole derivatives; in addition, pyridine derivatives are formed in the reaction with dimethyl fumarate. In the absence of a dipolar compound, ketenimines-ylides give N-aryl-N-(2,2-diphenylvinyl)amides of di- and trichloracetic acids.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1336–1342, October, 1987. 相似文献
4.
Enantioselective short formal synthesis of (+)-precapnelladiene (1) was achieved from a bicyclo[3.2.0]heptane derivative, which was prepared enantioselectively by chiral copper-catalyzed [2+2]-cycloaddition reaction of 2-methoxycarbonyl-2-cyclopenten-1-one with phenylthioacetylene developed by us. 相似文献
5.
2-(tert-Butyl)-3,7-dehydrotropone (7-(tert-butyl)bicyclo[3.2.0]hepta-1(7),2,4-trien-6-one; 1 ) was found to dimerize reversibly to 2A by [2 + 4]-cycloaddition/cycloreversion reaction. The equilibrium lies on the side of the highly strained dimer 2A in the solid state, and on the side of the monomer 1 in solution. The [2 + 4]-reaction is fully perisite-, regio- and stereoselective. Above room temperature, 1 irreversibly formed a decarbonylated dimer 6 , probably via the intermediate 9A or 9B , which resulted either from a dimerisation of 1 by [4 + 6]-cycloaddition or from a sigmatropic rearrangement of the originally formed dimer 2A or 2B . Similary, the 6-bromo derivative 14 afforded the corresponding decarbonylated dimer 15 . Should the formation of 6 and 15 be due to a primary cycloaddition then that reaction is fully peri-, site- and regioselective. Mild LiAlH4-reduction of 6 and subsequent acetylation yielded the acetate 11 , the structure of which was established by an X-ray analysis. More vigorous LiAlH4-treatment also reduced the terminal fulvenoid double bond of 6 and acetylation of the crude product led to the acetated 12 and 13 . 相似文献
6.
A. F. Khlebnikov I. V. Voznyi M. S. Novikov R. R. Kostikov 《Russian Journal of Organic Chemistry》2005,41(4):560-566
Geminal dichloroazomethine ylides generated by reaction of dichlorocarbene with Schiff bases derived from O-alkenyl- or O-alkynylsalicylaldehyde undergo intramolecular [3 + 2]-cycloaddition with participation of the olefinic or acetylenic dipolarophile to afford chromeno[4,3-b]pyrrole and chromeno[4,3-b]pyridine derivatives. The greatest yields of the intramolecular cycloaddition products were obtained from N-methyl-substituted dichloroazomethine ylides, whereas the main stabilization path of N-phenyl and N-tert-butyl derivatives was cyclization to geminal dichloroaziridines.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 4, 2005, pp. 571–577.Original Russian Text Copyright © 2005 by Khlebnikov, Voznyi, Novikov, Kostikov. 相似文献
7.
8.
Macías A Alonso E Del Pozo C Venturini A González J 《The Journal of organic chemistry》2004,69(21):7004-7012
The synthesis of enantiomerically pure modified proline derivatives was achieved by using spiro beta-lactams as starting material that were prepared in turn by the [2+2]-cycloaddition of unsymmetrical cyclic ketenes with optically active imines. A theoretical study of the [2+2]-cycloaddition reaction, using density-functional methods, gave insights on the origin of the observed stereoselectivity of the Staudinger reaction. The spiro beta-lactams were transformed in the N-Boc derivatives and subjected to nucleophilic ring opening, affording the corresponding enantiomerically pure modified proline derivatives, isolated as orthogonally protected compounds. 相似文献
9.
Prof. Dr. Jun-An Xiao Xiu-Liang Cheng Hai Peng Jin-Shao Liang Xiao-Yan Luo Prof. Dr. Wei Su 《化学:亚洲杂志》2021,16(17):2435-2438
The unexpected gold-catalyzed formal [3+2]-cycloaddition of N-2,2,2-trifluoroethylisatin ketimines with 2-(1-Alkynyl)-2-alken-1-ones is reported. Both diastereomers of the corresponding cycloadducts were formed in moderate to excellent yields with excellent diastereoselectivities by switching the catalytic system from mono-gold to gold/silver bimetallic catalytic system. The practicality of this protocol is demonstrated by scale-up reaction and the transformations of the cycloadduct. 相似文献
10.
[reaction: see text] 1-Phenylsulfonylallenes possessing a hexynyl appendage in refluxing toluene in the presence of catalytic amount of rhodium(I) catalyst under a carbon monoxide atmosphere underwent regioselective formal [2 + 2 + 1]-cycloaddition to produce the corresponding bicyclo[5.3.0]dec-1,7-dien-9-one derivatives in acceptable yields. 相似文献
11.
[formula: see text] The angiotensin converting enzyme inhibitor (-)-A58365A (1) was synthesized by a process based on the [3 + 2]-cycloaddition reaction of a phenylsulfonyl-substituted isomünchnone intermediate. The starting material for this process was prepared from L-pyroglutamic acid and involved using a diazo-phenylsulfonyl-substituted pyrrolidine imide. Treatment of the diazoimide with Rh2(OAc)4 in the presence of methyl vinyl ketone afforded a 3-hydroxy-2-pyridone derivative which was subsequently converted to the ACE inhibitor in six additional steps. 相似文献
12.
Dr. Yongming Deng Lynée A. Massey Dr. Peter Y. Zavalij Prof. Dr. Michael P. Doyle 《Angewandte Chemie (International ed. in English)》2017,56(26):7479-7483
The first asymmetric [3+1]-cycloaddition was successfully achieved by copper(I) triflate/double-sidearmed bisoxazoline complex catalyzed reactions of β-triisopropylsilyl-substituted enoldiazo compounds with sulfur ylides. This methodology delivered a series of chiral cyclobutenes in good yields with high enantio- and diastereoselectivities (up to 99 % ee, and >20:1 d.r.). Additionally, the [3+1]-cycloaddition of catalytically generated metallo-enolcarbenes was successfully extended to reaction with a stable benzylidene dichlororuthenium complex. 相似文献
13.
[formula: see text] beta-Functionalized nitroso alkene 2, obtained from methyl beta-nitropropionate 1 and N,O-bis(trimethylsilyl)acetamide, can function as a good heterodienophile in Diels-Alder reactions. Therefore, 2 was trapped by cyclic dienes to give adducts 4 with the corresponding stereoselectivity. Cycloadduct 4a undergoes retro-[4 + 2]-cycloaddition at 33 degrees C in solution; thus 4a can be used to generate nitroso alkene 2 in neutral medium. Cyclopentadiene reacts with adduct 4a according to an endo-(4 + 2]-cycloaddition scheme to give cycloadduct 5 in low yield. 相似文献
14.
D. A. Klok M. M. Shakirov V. V. Grishko V. A. Raldugin 《Russian Chemical Bulletin》1995,44(12):2412-2414
Vilsmeier—Haack formylation of methyl lambertianate results in its 16-formyl derivative as the predominant product, which readily enters the intramolecular reaction of photochemical [2+2]-cycloaddition in the absence of a sensitizer.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2514–2517, December, 1995. 相似文献
15.
Acylation of substituted 4-(furyl-2)-4-arylaminobut-1-enes with maleic anhydride provided 2-allyl-6-carboxy-4-oxo-3-aza-10-oxatricyclo[5.2.1.01,5]dec-8-enes in high yield under mild reaction conditions. The Diels-Alder adducts are formed via an initial amide formation followed by a stereoselective intramolecular [4+2] exo-cycloaddition reaction. Treatment of the tricyclic compounds with phosphoric acid at high temperatures (70-120 °C) promoted cyclic ether opening, intramolecular cyclization and aromatization to give the corresponding tetracyclic compounds, 5,6,6a,11-tetrahydro-10-carboxyisoindolo[2,1-a]quinolines, in moderate yields. The influence of the acid and the reaction temperature on the cyclization reactions are also discussed. 相似文献
16.
The 3-(2-propenylidene)-β-lactams 1a–c react as semicyclic dienes with the dihydrotriazole-diones 2 in a stereoselective fashion leading to the cycloadducts 3 . The 3′,3′-disubstituted derivative 4 gives no [4 + 2]-cycloaddition products but forms the adducts 5 and 6 . Sterochemistry and reaction pathways are discussed. 相似文献
17.
Dr. Michael Essers Prof. Dr. Günter Haufe 《European journal of organic chemistry》2023,26(17):e202300206
An eight-step linear sequence for the preparation of two diastereomers of an 8-fluoro-ABC-steroid building block was developed. Key step was an intramolecular Diels–Alder reaction of an intermediate o-quinodimethane formed from a benzocyclobutene substituted with a 5-fluorohex-5-en-4-one chain. This side chain was prepared from 6-chlorohex-1-ene by bromofluorination, elimination of HBr, Finkelstein reaction and alkylation of a literature-known benzocyclobutene derivative with the thus-formed 6-iodo-2-fluorohex-1-ene. Allylic oxidation of side chain's fluorovinyl moiety to an α-fluoro-α,β-unsaturated ketone completed the preparation of the precursor for the [4+2]-cycloaddition. 相似文献
18.
Nikolai V. YashinElena B. Averina Sergei M. GerdovTamara S. Kuznetsova Nikolai S. Zefirov 《Tetrahedron letters》2003,44(45):8241-8244
The reaction of ethyl nitrodiazoacetate with a series of methylenecyclobutanes was studied and both [1+2]- and [2+3]-cycloaddition pathways were observed depending on olefin structure. Amino acids of a spirohexane type were synthesized from methylenecyclobutanes by a three-step synthesis. 相似文献
19.
M. A. Kirpichenok L. M. Mel'nikova D. S. Yufit Yu. T. Struchkov I. I. Grandberg L. K. Denisov 《Chemistry of Heterocyclic Compounds》1988,24(9):965-974
The photocycloaddition of styrene to 4-methyl-7-aminocoumarin, 4-methyl-7-diethylaminocoumarin, 7-(N-morpholino) coumarin, 3-ethoxycarbonylmethyl-4-methyl-7-diethylaminocoumarin, and coumarin-102 (2,3,6,7-tetrahydro-9-methyl-1H, 5H,11H-[l]-benzopyrano[6,7,8-ij] quinolizin-11-one) was investigated. Adducts of regio- and stereospecific [2 + 2]-cycloaddition to the 3–4 bond were isolated. It was established by means of x-ray diffraction analysis that the phenyl group in the cycloadducts occupies the 1-endo position. The participation of the singlet excited states of the 7-aminocoumarin molecules in [2 + 2]-cycloaddition was demonstrated.See [1] for Communication 1.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1176–1184, September, 1988. 相似文献
20.
Yu. V. Khoroshavina G. A. Nikolaev G. A. Emel’yanov 《Russian Journal of General Chemistry》2010,80(11):2309-2313
Reaction of hexafluoropropene with butadiene and cyclopentadiene in a stationary system was studied. The reaction of hexafluoropropene
with burtadiene was shown to proceed along the scheme of [2+2]-cycloaddition, and with cyclopentadiene, as [2+4]-cycloaddition. 相似文献