- RADICAL REACTIONS OF (2-TRIMETHYLSILYLALLYL)TRIPHENYLSTANNANE WITH ALKYL HALIDES: A NEUTRAL ACETONE ENOLATE EQUIVALENT
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Facile transfer of 2-trimethylsilylallyl group is achieved when (2-trimethylsilylallyl)triphenylstannane is reacted with some halides under radical reaction conditions.
- Lee, Eun,Yu, Sang-Gu,Hur, Chang-Uk,Yang, Seung-Min
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- Synthesis of (1-Halo-1-alkenyl)trimethylsilanes via gem-Trimethylsilylation of Vinyl Halides
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Various vinyl halides including enol silyl ethers of α-halo ketones and esters give the corresponding (1-halo-1-alkenyl)trimethylsilanes in fair to good yields on treatment with lithium diisopropylamide at Dry Ice temperature in the presence of chlorotrimethylsilane.
- Shimizu, Nobujiro,Shibata, Fumihiro,Tsuno, Yuho
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- An efficient synthesis of 2-trimethylsilyl-2-propenal, a useful three- carbon synthon
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A formal efficient synthesis of 2-trimethylsilyl-2-propenal (2), a potentially useful synthetic reagent, is hereby described. The readily available α-bromovinyltrimethylsilane can be converted into 2- trimethylsilyl-2-propen-1-ol (1) via Grignard formation followed by addition of paraformaldehyde. The alcohol 1 can be oxidized using Jones reagent or PCC to yield the desired aldehyde 2.
- Hsung
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- Stereospecific 1,4-polymerization of 2,3-bis(trimethylsilyl)-1,3-butadiene
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Polymerization of 2,3-bis(trimethylsilyl)-1,3-butadiene in hexane/HMPA catalyzed by n-butyllithium yields trans-1,4-poly.This polymer has been characterized by 1H, 13C and 29Si NMR as well as IR spectroscopy and elemental analysis.The stereochemistry of the carbon-carbon double bonds has been established by protodesilation of the polymer with HI.The molecular weight distribution of the polymer has been determined by gel permeation chromatography and its thermal stability by thermogravimetric analysis.
- Ding, Yi-Xiang,Weber, William P.
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- Trimethylsilylacetylene synthesis process
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The invention discloses a process route for synthesizing trimethylsilylacetylene, which comprises the following steps of: generating trimethylchlorosilylethylene by taking ethylene bromide and trimethylchlorosilane as initial raw materials through a Grignard method, and forming 1-bromo trimethylchlorosilylethylene under the action of alkali through a bromination reagent; and removing monomolecularhydrogen bromide under the action of strong alkali to generate trimethylsilylacetylene. Compared with the traditional process, the process route has the advantages that the use of gas acetylene is avoided, the risk is reduced, the safety is improved, the used raw materials are easily available, the operation is easy, the safety and the environmental protection are realized, and the industrial production can be realized.
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Paragraph 0022; 0023
(2021/01/11)
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- Intermediate for preparing halichondrin compound and preparation method thereof
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The invention relates to an intermediate for preparing a halichondrin compound and a preparation method thereof. The invention particularly relates to an intermediate for preparing halichondrin, eribulin or analogues thereof, and a preparation method and application of the intermediate. The intermediate as well as the preparation method and application thereof are used for constructing C20-C26 structural fragments of the halichondrin compound. The initial raw materials of the synthesis route are cheap, easy to obtain, stable in source and reliable in quality; the structural characteristics ofreactants are fully utilized in the selection of a chiral center construction method, so that the synthesis efficiency is practically improved, and the difficulty and risk of product quality control are reduced; and the use of a high-toxicity and expensive organic tin catalyst is avoided, so that the cost and the environmental friendliness are remarkably improved.
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Paragraph 0132; 0139-0142
(2020/07/07)
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- Removable Silyl Group as a "masked Proton" in Oxy-2-oxonia(azonia)-Cope Rearrangement: Applications in Stereoselective Total Synthesis of Natural Macrolides
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In the presence of a Lewis acid, trimethylsilyl-substituted β,γ-unsaturated ketones and aldehydes (imines) undergo nucleophilic addition to produce zwitterionic intermediates, followed by oxy-2-oxonia(azonia)-Cope rearrangements to give homoallylic esters (amides). In the case of TMS-containing 2-vinylcycloalkanones, the process results in ring-enlargement, providing 10- to 16-membered lactones. This protocol was applied to the total synthesis of (R)-phoracantholide I.
- Mu, Wenbo,Zou, Yue,Zhou, Lijun,Wang, Quanrui,Goeke, Andreas
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supporting information
p. 4982 - 4989
(2015/08/03)
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- Catalytic asymmetric Claisen rearrangement in natural product synthesis: Synthetic studies toward (-)-xeniolide F
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(Chemical Equation Presented) The catalytic asymmetric Claisen rearrangement (CAC) of a highly substituted and functionalized α-alkoxycarbonyl-substituted allyl vinyl ether has been exploited to gain access to an advanced building block for the projected total synthesis of (-)-xeniolide F, the enantiomer of a xenicane diterpene isolated from a coral of the genus Xenia.
- Pollex, Annett,Hiersemann, Martin
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p. 5705 - 5708
(2007/10/03)
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- 1-Bromo-1-lithioethene: A practical reagent in organic synthesis
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A reliable preparative scale synthesis of 1-bromo-1-lithioethene is reported. This reagent undergoes clean 1,2-addition with a range of aldehydes and ketones at -110 °C to afford the corresponding 2-bromo-1-alken-3-ols in moderate to excellent yield. Trapping with other electrophiles (acylsilanes, chlorosilanes, tributyltin chloride, iodine) cleanly provides practically useful yields of various 1-substituted 1-bromoethene products. Unexpectedly high diastereoselectivities were observed during the addition of 1-bromo-1- lithioethene to α-siloxy aldehydes (typically 10:1, Felkin-Ahn control) and protected ketopyranose and ketofuranose sugars (> 10:1, addition from the less-hindered face). The title organolithium reagent possesses relatively low basicity at low temperature, and is compatible with a variety of common protecting groups. We believe that these unusual properties of 1-bromo-1-lithioethene may originate from the specific crystalline structure of the reagent in which lithium is coordinatively saturated and thus unavailable for chelation. 2005 American Chemical Society.
- Novikov, Yehor Y.,Sampson, Paul
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p. 10247 - 10259
(2007/10/03)
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- 1-Bromo-1-lithioethene: A practical reagent for the efficient preparation of 2-bromo-1-alken-3-ols
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(Matrix presented) A reliable preparative-scale synthesis of 1-bromo-1-lithioethene is reported. This reagent undergoes clean 1,2-addition with a range of aldehydes and ketones at -105°C to afford the corresponding 2-bromo-1-alken-3-ols in moderate to excellent yield. Efficient diastereoselective addition to α-siloxy and α-methylcyclohexanones, as well as protected 3-keto furanose sugars, is achieved in the presence of 10 mol% CeBr3. The resulting bromoallylic alcohol adducts have considerable potential as synthetic building blocks.
- Novikov, Yehor Y.,Sampson, Paul
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p. 2263 - 2266
(2007/10/03)
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- Synthetic Studies on Bicyclomycin and its Analogues. Part 1. Synthesis of Substituted 2-Oxa-8,10-diazabicyclodecanes
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Methods have been developed for formation of the eight-membered oxygen-containing ring system (2) present in the antibiotic bicyclomycin.The procedure starts with N,N'-disubstituted piperazine-2,5-diones or the corresponding mono imino ethers.A new method is based on the oxidation of the mono imino ethers using 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) as oxidant: the bis imino ethers gave pyrazines under these conditions, whilst the parent piperazinedione proved to be unreactive.
- Dawson, Ian M.,Gregory, Julian A.,Herbert, Richard B.,Sammes, Peter G.
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p. 2585 - 2594
(2007/10/02)
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- A New Approach to Bicyclomycin
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A simple route to the bicyclomycin nucleus (2) is described which involves use of a β-vinyl sulphone as a new vinylic cation synthon.
- Dawson, Ian M.,Gregory, Julian A.,Herbert, Richard B.,Sammes, Peter G.
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p. 620 - 621
(2007/10/02)
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