- Chemiluminescence-promoted oxidation of alkyl enol ethers by NHPI under mild conditions and in the dark
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The hydroperoxidation of alkyl enol ethers using N-hydroxyphthalimide and molecular oxygen occurred in the absence of catalyst, initiator, or light. The reaction proceeds through a radical mechanism that is initiated by N-hydroxyphthalimide-promoted autoxidation of the enol ether substrate. The resulting dioxetane products decompose in a chemiluminescent reaction that allows for photochemical activation of N-hydroxyphthalimide in the absence of other light sources.
- Anderson,Andia, Alexander A.,Woerpel
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supporting information
(2021/02/03)
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- One-pot enol silane formation-Mukaiyama aldol reactions: Crossed aldehyde-aldehyde coupling, thioester substrates, and reactions in ester solvents
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Trimethylsilyl trifluoromethanesulfonate (TMSOTf) and a trialkylamine base promote both in situ enol silane/silyl ketene acetal formation and Mukaiyama aldol addition reactions between a variety of reaction partners in a single reaction flask. Isolation of the required enol silane or silyl ketene acetal is not necessary. For example, crossed aldol reactions between α-disubstituted aldehydes and non-enolizable aldehydes yield β-hydroxy aldehydes in good yield. In a related reaction, the common laboratory solvent ethyl acetate functions as both an enolate precursor and a green reaction solvent. When thioesters are employed as enolate precursors, high yields for additions to non-enolizable aldehydes are routinely observed.
- Downey, C. Wade,Dixon, Grant J.,Ingersoll, Jared A.,Fuller, Claire N.,MacCormac, Kenneth W.,Takashima, Anna,Sediqui, Rohina
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supporting information
(2019/10/14)
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- Stereoselective Synthesis of Trisubstituted Vinylboronates from Ketone Enolates Triggered by 1,3-Metalate Rearrangement of Lithium Enolates
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An unprecedented stereoselective synthesis of trisubstituted vinylboronates is reported to proceed by direct borylation of lithium ketone enolates under transition-metal-free conditions. The stereospecific C?O borylation of lithium enolates was triggered by a carbonyl-induced 1,3-metalate rearrangement via a C-bound boron enolate. DFT calculations and control experiments revealed that the stereoselectivity is controlled by sterics. A variety of stereospecific trisubstituted vinylboronates, together with several tetrasubstituted vinylboronates, were conveniently synthesized with the newly developed methodology. Based on the transformation of stereospecific vinylboronate, a single isomer of Dienestrol was efficiently obtained.
- Hu, Yue,Sun, Wei,Zhang, Tao,Xu, Nuo,Xu, Jianeng,Lan, Yu,Liu, Chao
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supporting information
p. 15813 - 15818
(2019/10/28)
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- Silazanes/catalytic bases: Mild, powerful and chemoselective agents for the preparation of enol silyl ethers from ketones and aldehydes
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We have developed an efficient method for the preparation of enol silyl ethers using novel agents, silazanes together with NaH or DBU catalyst, wherein TMS and TBDMS groups were smoothly and chemoselectively introduced into ketones and aldehydes under mil
- Tanabe, Yoo,Misaki, Tomonori,Kurihara, Minoru,Iida, Akira,Nishii, Yoshinori
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p. 1628 - 1629
(2007/10/03)
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- Preparation of silyl enol ethers using (bistrimethylsilyl)acetamide in ionic liquids
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(matrix presented) Ionic liquids have been used for the preparation of silyl enol ethers from aldehydes and ketones with (bistrimethylsilyl)acetamide (BSA) in good yields.
- Smietana, Michael,Mioskowski, Charles
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p. 1037 - 1039
(2007/10/03)
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- Scope and limitations of the [1,2]-alkylsulfanyl (SMe, SEt and SCH2Ph) and sulfanyl (SH) migration in the stereospecific synthesis of substituted tetrahydrofurans
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Acid catalysed rearrangement of a series of 4-RS-1,3-diols (R = Me, Et, Bn and H) with toluene-p-sulfonic acid in dichloromethane gives stereospecifically substituted tetrahydrofurans via a [1,2]-SR shift in near quantitative yield. We comment on the structural variation of the migrating (RS) substituent and that of the migration origin and terminus on the outcome of the title reaction. We also report on the surprising similarity between an alkylsulfanyl (RS) and sulfanyl (SH) migrating group.
- Eames, Jason,Kuhnert, Nikolai,Warren, Stuart
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p. 138 - 143
(2007/10/03)
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- Facile synthesis of silyl enol ethers by Mg-promoted coupling of aliphatic carbonyl compounds with trimethylsilyl chloride
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Treatment of aliphatic carbonyl compounds with trimethylsilyl chloride with Mg turning for Grignard reaction without any pre-treatment in N,N- dimethylformamide at room temperature brought about highly facile, effective and stereoselective coupling to give the corresponding silyl enol ethers in good yields.
- Ishino, Yoshio,Kita, Yoshio,Maekawa, Hirofumi,Ohno, Toshinobu,Yamasaki, Yasuhiro,Miyata, Toshiyuki,Nishiguchi, Ikuzo
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p. 1349 - 1352
(2007/10/03)
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- Easy preparation of enoxysilanes from aldehydes and ketones catalyzed by samarium diiodide
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Ketones and α-substituted aldehydes are converted to trimethylsilyl enol ethers by reaction with the trimethylsilyl ketene acetal of methyl isobutyrate in dichloromethane in presence of a catalytic amount of samarium diiodide.
- Hydrio, Jerome,Van De Weghe, Pierre,Collin, Jacqueline
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- Formation of quaternary centres via iron allyl cations. Rapid entry into spirocyclic ring systems
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Ester-substituted allyltetracarbonyliron cations react with cycloalkylidene-type silyl enol ethers, silyl ketene acetals, and β-keto- esters to give 1,6-dicarbonyl compounds containing a newly formed quaternary centre. Selected condensation products are c
- Charlton, M. Anne,Green, James R.
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p. 965 - 974
(2007/10/03)
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- Efficient alkylsulfanyl (SMe, SEt and SCH2Ph) and sulfanyl (SH) migration in the stereospecific synthesis of substituted tetrahydrofurans
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Treatment of a series of 4-RS-1,3-diols (R = Me, Et, Bn and H) with TsOH in CH2Cl2 gives substituted tetrahydrofurans. We discuss the scope of this reaction using structural variation of the migrating (RS) substituent. All reactions proceeded in high yield and give synthetically useful products.
- Eames, Jason,Jones, Ray V.H.,Warren, Stuart
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p. 4823 - 4826
(2007/10/03)
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- LITHIUM DIISOPROPYLAMIDE AS A HYDRIDE DONOR. REDUCTION OF ALDEHYDES.
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Lithium diisopropylamide reduces aldehydes to the corresponding alcohols and also forms adducts with aldehydes.Both processes can compete with enolization.
- Majewski, Marek
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p. 4057 - 4060
(2007/10/02)
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- 1,5-DICARBONYL COMPOUNDS A GENERAL PREPARATION METHOD
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In this report, a general method for the preparation of 1,5-dicarbonyl compounds and six membered ring annelation is described.This method involves the reaction of hemiacetal vinylogs 1 with enol ethers 2 or 3 in the presence of a Lewis acid.This reaction was successfully applied to the enol ethers of α and α,α'-hindered ketones such as 2,2,6-trimethyl cyclohexanone. α-Cyperone and 6-epi-α-cyperone were obtained using this process.
- Duhamel, P.,Hennequin, L.,Poirier, J. M.,Tavel, G.,Vottero, C.
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p. 4777 - 4786
(2007/10/02)
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- PHENYLTHIO(PhS) MIGRATION IN THE STEREOCONTROLLED SYNTHESIS OF ALLYLIC ALCOHOLS WITH 1,4 RELATED CHIRAL CENTRES.
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Stereoselective aldol products are transformed by PhS migration into lactones, tetrahydrofurans, and, by subsequent Evans-Mislow rearrangement, into the title compounds with complete stereochemical control.
- Aggarwal, Varinder K.,Warren, Stuart
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p. 101 - 104
(2007/10/02)
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- Preparation of a New, Highly Reactive Form of Iron(0) and Its Use in Deprotonation of Carbonyl Compounds
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A new, highly reactive form of zerovalent iron, prepared from the reaction of methylmagnesium bromide and ferric chloride, has been found to deprotonate cyclic unsymmetrical ketones in the presence of trimethylsilyl chloride to give thermodynamic (more substituted) silyl enol ethers regiospecifically.
- Krafft, Marie E.,Holton, Robert A.
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p. 3669 - 3670
(2007/10/02)
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- Vinyl Cations, 36. Solvolysis of Cycloalkylidenemethyl and 1-Cyclopenten-1-yl Triflates
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Cyclohexylidenemethyl triflate (2), cyclobutylidenemethyl triflate (5), 1-cyclopenten-1-yl triflate (7), bicyclohex-2-en-2-yl triflate (9), 1-cyclobutylideneethyl triflate (19), and 2-methyl-1-cyclopenten-1-yl triflate (29) were solvolyzed in solvents of various ionizing power and nucleophilicity and the solvolysis products were identified.The cyclobutylidenealkyl triflates solvolyze via a vinyl cation mechanism involving ion pairs with rearrangement to cyclopentene and cyclopentanone compounds.The 1-cyclopenten-1-yl triflates do not produce vinyl cation intermediates but give only the corresponding ketones via an O - S bond cleavage of the triflate group.
- Hanack, Michael,Maerkl, Rainer,Martinez, Antonio Garcia
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p. 772 - 782
(2007/10/02)
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- Carbon-Carbon Bond Formation by the Use of Chloroiodomethane as a C1 Unit. III. A Convenient Synthesis of the Mannich Base from Enol Silyl Ether by a Combination of Chloroiodomethane and N,N,N',N'-Tetramethylmethanediamine
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The Mannich dimethylaminomethylation of carbonyl compounds is conveniently carried out via enol trimethylsilyl ethers by a combination of chloroiodomethane (CH2ClI) and N,N,N',N'-tetramethylmethanediamine (TMMD) in DMSO as the solvent at ambient temperatute.The mechanism of the transformation is discussed on the basis of product analysis and 1H NMR spectral studies.The reagent system CH2ClI/TMMD also provides a convenient route to the Eschenmoser's salt ().
- Miyano, Sotaro,Hokari, Hiroshi,Hashimoto, Harukichi
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p. 534 - 539
(2007/10/02)
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