- Site-Selective Aliphatic C?H Silylation of 2-Alkyloxazolines Catalyzed by Ruthenium Complexes
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The Ru-catalyzed dehydrogenative silylation of 2-alkyloxazolines with 1,1,1,3,5,5,5-heptamethyltrisiloxane took place site-selectively at methyl C(sp3)?H bonds located γ to the nitrogen atom of the oxazolyl groups. Pyridine and pyrazole rings could also be used as a directing group. A catalytic mechanism based upon successive σ-bond metathesis is proposed.
- Kon, Kazumasa,Suzuki, Hiroyuki,Takada, Kosuke,Kohari, Yoshihito,Namikoshi, Takeshi,Watanabe, Shinji,Murata, Miki
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Read Online
- Nucleophilic addition of arylmethylzinc reagents (ArCH2ZnCl) to formaldehyde: An easy access to 2-(hetro)arylethyl alcohols
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The selective addition of arylmethylmagnesium halides with formaldehyde giving arylethyl alcohols is extremely challenging. To circumvent the difficulties, in the current communication, we have reported on the nucleophilic addition of benzyl zinc reagents derived from inexpensive and abundant benzyl chlorides to paraformaldehyde. The reaction investigated herein is hitherto unknown and was found to be selective, operationally simple, atom- and step-economical and high yielding to deliver phenethyl alcohols utilized as key perfumery ingredients in 60–83% yields. After successful establishment of the reaction condition, the reaction was also scaled up successfully to deliver a large-scale preparation of the phenethyl alcohol.
- Bhatt,Samant,Pednekar, Suhas
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Read Online
- The benzyl can be selectively removed by visible light or near visible light. Method for protecting allyl and propargyl group
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The invention provides a method for selectively removing benzyl, allyl and propargyl protecting groups by visible light or near visible light, namely a substrate containing benzyl, allyl or propargyl protecting groups. The method has the advantages of simple operation, safe and clean visible light or near visible light as excitation conditions, cheap and easily available reagents, high reaction yield, high reaction chemistry and regional selectivity, and is suitable for selective removal of benzyl, allyl and propargyl protecting groups in various substrates.
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Paragraph 0029
(2021/10/16)
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- Chemoselective Cleavage of Si-C(sp3) Bonds in Unactivated Tetraalkylsilanes Using Iodine Tris(trifluoroacetate)
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Organosilanes are synthetically useful reagents and precursors in organic chemistry. However, the typical inertness of unactivated Si-C(sp3) bonds under conventional reaction conditions has hampered the application of simple tetraalkylsilanes in organic synthesis. Herein we report the chemoselective cleavage of Si-C(sp3) bonds of unactivated tetraalkylsilanes using iodine tris(trifluoroacetate). The reaction proceeds smoothly under mild conditions (-50 °C to room temperature) and tolerates various polar functional groups, thus enabling subsequent Tamao-Fleming oxidation to provide the corresponding alcohols. NMR experiments and density functional theory calculations on the reaction indicate that the transfer of alkyl groups from Si to the I(III) center and the formation of the Si-O bond proceed concertedly to afford an alkyl-λ3-iodane and silyl trifluoroacetate. The developed method enables the use of unactivated tetraalkylsilanes as highly stable synthetic precursors.
- Matsuoka, Keitaro,Komami, Narumi,Kojima, Masahiro,Mita, Tsuyoshi,Suzuki, Kimichi,Maeda, Satoshi,Yoshino, Tatsuhiko,Matsunaga, Shigeki
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supporting information
p. 103 - 108
(2021/01/13)
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- Synthesis method of (2-hydroxyethyl)pyridine
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The invention discloses a synthesis method of (2-hydroxyethyl)pyridine. The preparation method comprises the following step: reacting 2-methylpyridine with formaldehyde in a solvent under a pressure of 2-8 MPa and under the action of organic alkali so as to obtain (2-hydroxyethyl)pyridine, wherein the organic alkali is one or more selected from triethylene diamine, hexamethylenediamine, tetramethyl guanidine, 1,8-diazabicycloundec-7-ene and 1,5,7-triazabicyclo[4.4.0]deca-5-ene. When the method is used for preparing (2-hydroxyethyl)pyridine, reaction time is obviously shortened, a one-way conversion rate is high, and production cost can be saved.
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Paragraph 0040-0068
(2020/12/10)
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- Electrochemical Deoxygenation of N-Heteroaromatic N -Oxides
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An electrochemical method for the deoxygenation of N-heteroaromatic N -oxide to give the corresponding N-heteroaromatics has been developed. Several classes of N-heterocycles such as pyridine, quinoline, isoquinoline, and phenanthridine are tolerated. The electrochemical reactions proceed efficiently in aqueous solution without the need for transition-metal catalysts and waste-generating reducing reagents.
- Xu, H.-C.,Xu, P.
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supporting information
p. 1219 - 1221
(2019/06/08)
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- Preparation method of orthographic optimizing betahistine hydrochloride
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The invention discloses a preparation method of orthographic optimizing betahistine hydrochloride, and relates to the field of drug preparation. The preparation method includes the steps: adding raw materials into a reaction bottle according to the feeding ratio (molar ratio) of 2-methylpyridine to paraformaldehyde of 1:0.57, leading in nitrogen, stirring mixture for 20 hours at the temperature of125 DEG C and at 4 barometric pressure, performing reduced pressure distillation, and collecting distillation cut at the temperature of 130-145 DEG C and under the pressure of 16mm mercury columns toobtain light-yellow oily 2-hydroxyethyl pyridine; adding the 2-hydroxyethyl pyridine into a three-opening bottle, adding sodium hydroxide according to the feeding ratio of 2-(2-Hydroxyethyl)pyridineto sodium hydroxide of 1:0.05, heating the mixture to reach 95-100 DEG C, stirring the mixture for 2 hours, removing a water layer, performing reduced pressure distillation on an oil layer, and collecting the distillation cut at the temperature of 65-70 DEG C and under the pressure of 17mm mercury columns to obtain 2-vinylpyridine. The preparation method is simple in technological process, safe tooperate and mild in reaction, production efficiency and product quality can be greatly improved, and production cost is reduced.
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Paragraph 0009
(2018/07/30)
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- A vinyl pyridine production process (by machine translation)
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Vinyl pyridine is an important chemical products. The production flow: (1) 2 - hydroxy ethyl pyridine synthesis; (2) dehydration reaction; (3) the essence steams. (by machine translation)
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Page/Page column 2
(2017/07/20)
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- METHODS AND MATERIALS FOR PREPARING ORGANIC COMPOUNDS FROM PRIMARY AMINES
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Methods are disclosed for the conversion of primary amines to other functional groups. The methods can be used to prepare chiral organic compounds, including organic alcohols and organic halides. The methods can be carried out by treating a primary amine with an activating agent and a nitrosyl agent to produce the transformed compound along with nitrous oxide.
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Page/Page column 28-29
(2008/06/13)
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- Anionic, in situ generation of formaldehyde: A very useful and versatile tool in synthesis
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(Chemical Equation Presented) A very simple, safe and powerful method for the in situ generation of formaldehyde at low temperature in anhydrous conditions is described. This new tool avoids the use of gaseous formaldehyde and is suitable for basic carbon nucleophiles which cannot be generated in aqueous reaction media. Various substrates, including organolithium reagents and enolates, underwent smooth hydroxymethylation showing the versatility of this process. A Wittig reaction was also carried out in high yield.
- Deguest, Geoffrey,Bischoff, Laurent,Fruit, Corinne,Marsais, Francis
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p. 1165 - 1167
(2007/10/03)
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- N-substituted norephedrine chiral derivatives, their preparation and their use for the synthesis of optically active functionalised compounds by hydrogen transfer
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A ligand adapted for use in a process for enantioselective reduction of unsaturated compounds carrying functional groups by a hydrogen transfer method including an optically active N-substituted chiral derivative of norephedrine and the associated process.
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