- High Pressure Reaction of 1-Methoxy-3-trialkylsiloxybuta-1,3-diene with Aldehydes. Cycloaddition or Silicon Migration Reaction
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The high pressure reaction of Danishefsky's diene with aromatic aldehydes produces the cycloadduct, while with an aliphatic aldehyde such as 2-phenylpropionaldehyde the intermolecular silicon migration from oxygen to oxygen takes place.
- Yamamoto, Yoshinori
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- Method for preparing 2-chloro-4-methylpyridine-3-carbonitrile
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The invention discloses a method for preparing 2-chloro-4-methylpyridine-3-carbonitrile. The method comprises the following steps: at -20 DEG C to 50 DEG C, a hydrogen chloride solution is used for treating raw materials containing 4,4-dicyano-3-methyl-3-butenal dimethyl acetal. 2-chloro-4-methylpyridine-3-carbonitrile whose HPLC purity reaches 99% or above can be conveniently obtained, which has important meanings for subsequent preparation of high purity 2-chloro-4-methylpyridine-3-carbonitrile and nevirapine; the method has the advantages of short process route, simple operation, high yield, low cost, etc., a highly toxic product phosphorous oxychloride is avoided, discharge of waste water is reduced, and the method is very suitable for industrial production.
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Paragraph 0040; 0042
(2016/11/14)
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- Identification and synthesis of elymniafuran, a new monoterpene from the butterfly elymnias thryallis
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The main constituent of the scent gland secretion of the tropical butterfly Elymnias thryallis (Lepidoptera: Satyridae) could be identified as (S)-2-methyl-1-(4-methyl-2-furyl)-3-buten-2-ol (elymniafuran, 3). It is accompanied by small amounts of (E)- and (Z)-4-methyl-(2-methyl-1,3-butadienyl)-furan (4) as well as the spiro acetal 3,9-dimethyl-1,6-dioxaspiro[4.5]dec-3-ene (10). The structural assignment of these new natural products as well as the synthesis and enantiomeric separation by chiral gas chromatography are described. VCH Verlagsgesellschaft mbH, 1996.
- Schulz, Stefan,Steffensky, Mirjam,Roisin, Yves
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p. 941 - 946
(2007/10/03)
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- CYCLOADDITION OF 1-METHOXY-3-TRIMETHYLSILYLOXYBUTADIENE WITH HALOGENATED CARBONYL COMPOUNDS
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Cycloadditions of 1-methoxy-3-trimethylsilyloxy-1,3-butadiene (1) with halogenated carbonyl compounds (2) yielded corresponding substituted tetrahydro- and/or dihydropyran-4-ones (3 and/or 4).Lewis acids were found to be effective as catalysts.Reactions with less reactive carbonyl compounds (2c,d) afforded p-hydroxyacetophenone (5) produced by cyclodimerization of 1.Stereochemistry of the adducts was deduced by 1H nmr spectroscopy.
- Sera, Akira,Iwasaki, Yasuji,Umeda, Michio,Itoh, Kuniaki
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p. 273 - 278
(2007/10/02)
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- Chlorination of α,β-Unsaturated Ketones and Esters in the Presence of Acid Scavengers
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The chlorination of a series of α,β-unsaturated ketones and esters by Cl2 in CH3OH, with and without acid scavengers such as N-chlorosuccinimide (NCS), pyridine and 2,6-lutidine, is described.Methyl vinyl ketone and cyclohex-2-enone have also been chlorinated in ethanol.Mixtures of Markovnikov(M) and anti-Markovnikov(AM) methoxy chlorides and dichlorides are formed in most cases; phenyl vinyl ketone gives no M products in the absence of pyridine, M methoxy chloride is not formed with (E)-4-chlorobut-3-en-2-one under any conditions, pyridine has no effect on the product ratios and methyl 3-chlorobut-2-enoate forms only dichloride.Chlorination of the ketones in the presence of the pyridines results in a significant increase in the M regioisomer (except for methyl isopropenyl ketone and the ketones mentioned), giving M : AM ratios which are similar to the corresponding esters.Ratios for the esters are not affected significantly by pyridine.We ascribe the effect of the pyridine bases to the elimination of acid and the acid-catalysed mechanism, permitting the chlorination to occur via a carbon-carbon ?-bond (chloronium ion) mechanism.The rate of chlorination of methyl vinyl ketone is retarded by pyridine but is still considerably faster than methyl acrylate.NCS, in contrast to N-bromosuccinimide (NBS) reported previously, has no effect on the M : AM ratio.The chlorination of methyl vinyl ketone with NCS and HCl gives markedly different results from Cl2.
- Heasley, Victor L.,Elliott, Stephen L.,Erdman, Paul E.,Figueroa, Daphne E.,Krosley, Kevin W.,et al.
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p. 393 - 399
(2007/10/02)
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- THE TWO STAGES OF THE ACID-CATALYZED HYDRATION OF 1-ALKOXY-1-BUTEN-3-YNES AND THE EFFECT OF CIS-TRANS ISOMERISM
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The kinetics of the acid-catalyzed hydrolysis of alkoxybutenynes under mild conditions were studied, and this made it possible to measure the rate of the first stage of the reaction.It was shown that the reaction rate depends on the configuration of the initial alkoxybutenynes.
- Vavilova, A. N.,Trofimov, B. A.,Volkov, A. N.,Keiko, V. V.
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p. 809 - 812
(2007/10/02)
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