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1.
《Tetrahedron letters》1989,30(2):239-242
Silyl enol ethers (2) react with tributyl [(phenylthio) chloromethyl] stannane (1) in the presence of Zinc bromide to give β-phenylthiomethylstannyl ketones (3) in good yields. Silyl dienol ethers (4) mainly give products (5) due to γ-attack, under these conditions. 相似文献
2.
Florine Cavelier Sylvie Gomez Robert Jacquier Jean Verducci 《Tetrahedron: Asymmetry》1993,4(12):2501-2505
The deracemization by enantioselective protonation of silyl enol ethers was tested using 2,2-dimethyl 5-phenyl 1,3-dioxolan 4-one 1. The results obtained, especially with pantolactone as a chiral proton donor, are better than when the deracemization is carried out with the lithium enolate of 1. 相似文献
3.
Nucleophilic reactions of various enol silyl ethers with carbocation species generated from propargyl silyl ethers by the action of a Lewis acid have been developed. The present method is highly useful for the introduction of allenic or enyne functionalities into the alpha-position of substituted ketones. [reaction--see text] 相似文献
4.
Site-specific ureidoalkylation of silyl enol ethers can be achieved by their reactions with chloromethylcarbamates at ?78° under the influence of titanium tetrachloride. 相似文献
5.
A. V. Shastin O. A. Rakitin T. I. Godovikova Yu. A. Strelenko F. I. Dubovitskii L. I. Khmel'nitskii 《Russian Chemical Bulletin》1988,37(6):1282-1282
Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1447–1448, June, 1988. 相似文献
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Ring out the old: The cycloisomerization of alkynyl silyl enol ethers proceeds at ambient temperature under the mild conditions of silver catalysis. Mono- or bicyclic spiro compounds can be obtained by 5-exo-dig reactions. Trapping the vinyl silver species with an iodide source, such as N-iodosuccinimide (NIS), afforded the alkenyl iodide derivatives. 相似文献
9.
A new oxygen-centered radical cyclization onto silyl enol ethers has been developed and utilized for the synthesis of versatile siloxy-substituted tetrahydrofurans. The reactions display excellent chemoselectivity for cyclization onto the electron-rich silyl enol ether when competing terminal alkene cyclization, 1,5-hydrogen abstraction, and beta-fragmentation pathways are present. The increased chemoselectivity also allows for the synthesis of tetrahydropyrans, a challenging substrate class to access using oxygen-centered radical alkene cyclizations due to competing 1,5-hydrogen abstractions. 相似文献
10.
A facile, regiospecific entry to α-alkoxymethyl ketones is described. 相似文献
11.
[reaction: see text] The radical trifluoromethylation of ketone silyl enol ethers gave alpha-CF(3) ketones in good yields with wide scope of the ketonic substrates including acyclic ketones and cyclopentanone. The use of dialkylzinc to activate the silyl enol ethers is the key to the efficient radical trifluoromethylation. 相似文献
12.
Hiroharu Suzuki Yoshihiko Koyama Yoshihiko Moro-Oka Tsuneo Ikawa 《Tetrahedron letters》1979,20(16):1415-1418
A novel synthetic method for silyl enol ethers from allyl alcohols was developed using ruthenium hydride catalyst. 相似文献
13.
《Tetrahedron letters》1986,27(12):1385-1386
Si]yl enol ethers (1,2) are γ-alkylated in moderate yields by a series of vinyl thionium ions generated from the corresponding allylic sulphoxides (3–6) with TMSOTf and diisopropylethylamine in CH2Cρ at –78°C. 相似文献
14.
《Tetrahedron letters》1986,27(23):2563-2566
The N-chlorosuccinimide (NSC) reaction of a number of cyclic and acyclic trimethylsilyl enol ethers was investigated. Based on product analyses, the mechanism of the reaction is postulated to involve a step-wise process. 相似文献
15.
Hans-Ulrich Reissig 《Tetrahedron letters》1985,26(33):3943-3946
Methyl 2-siloxycyclopropanecarboxylates rearrange smoothly and quantitatively to the corresponding silyl enol ethers (3) by addition of a catalytical amount of iodo trimethylsilane. Scope and limitation of this novel process as well as the synthesis of the electron rich diene (10a) are described. 相似文献
16.
Langer P Döring M Seyferth D Görls H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2001,7(3):573-584
The first elimination reactions of silyl enol ethers to lithiated allenes are reported. These reactions allow a direct transformation of readily available silyl enol ethers into functionalized allenes. The action of three to four equivalents of lithium diisopropylamide (LDA) on silyl enol ethers results in the formation of lithiated allenes by initial allylic lithiation, subsequent elimination of a lithium silanolate, and finally, lithiation of the allene thus formed. Starting with amide-derived silyl imino ethers, lithiated ketenimines are obtained. A variety of reactions of the lithiated allenes with electrophiles (chlorosilanes, trimethylchlorostannane, dimethyl sulfate and ethanol) were carried out. Elimination of silanolate is observed only for substrates that contain the hindered SiMe2tBu or Si(iPr)3 moiety, but not for the SiMe3 group. The reaction of 1,1-dilithio-3,3-diphenylallene with ketones provides a convenient access to novel 1,1-di(hydroxymethyl)allenes which undergo a domino Nazarov-Friedel-Crafts reaction upon treatment with p-toluenesulfonic acid. 相似文献
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Higashiya S Chung WJ Lim DS Ngo SC Kelly WH Toscano PJ Welch JT 《The Journal of organic chemistry》2004,69(19):6323-6328
A variety of mono- and difluoroacetylsilanes and the corresponding silyl enol ethers were prepared from trifluoroethanol and chlorotrialkylsilanes in the presence of LDA through retro-Brook rearrangement. Sterically demanding silyl groups, especially those bound to oxygen, resulted in higher yields of difluoroacetylsilanes. The yields of difluoroacetylsilanes were also dramatically affected by the method of the termination of the reaction. Difluorohaloacetylsilanes were prepared from the corresponding difluoroethenyl silyl ethers with electrophilic halogenating reagents in good yields. A gamma-fluorinated beta-diketone 9a was prepared from monofluoroacetyltriisopropylsilane by nucleophilic acylation with methyl trifluoroacetate. 相似文献
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We describe here a Tf?NH-catalyzed formal (3+3) cycloaddition of silyl enol ethers with acrylates as a new domino reaction. In the domino sequence, the catalyst activates Michael addition, deprotonation of the resulting silyloxonium cation and intramolecular Claisen condensation. It was found that reaction modes significantly depend on the reaction temperature. We also examined the mechanistic detail of the reaction by 1H-NMR experiment. 相似文献