- Expedient synthesis of quadrilure antipodes, the pheromone of square-necked grain beetle
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Both the enantiomers of the title pheromone, (E)-3-methyl-7-acetoxynon-3-ene (I) have been synthesized in high enantiomeric excess via a stereoselective route. Thus, easily accessible, 3-methylpent-1-en-3-ol (2) was converted via a Claisen orthoester rearrangement to the ester (3) with exclusive (E)-geometry. Its derivatization to the aldehyde (5) followed by reaction with ethylmagnesium bromide gave the racemic pheromone alcohol (6) in 27.7% overall yield. Its enantioselective lipase catalyzed trans-esterification directly afforded (R)-I, while its antipode was obtained from the resolved alcohol by chemical acetylation.
- Pawar,Chattopadhyay
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Read Online
- Gold-Catalyzed Iminations of Terminal Propargyl Alcohols with Anthranils with Atypical Chemoselectivity for C(1)-Additions and 1,2-Carbon Migration
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This work reports gold-catalyzed iminations of terminal propargyl alcohols with anthranils or isoxazoles to yield E-configured α-amino-2-en-1-ones and -1-als with complete chemoselectivity. These catalytic iminations occur exclusively with C(1)-nucleophilic additions on terminal alkynes, in contrast to a typical C(2)-route. For 3,3-dialkylprop-1-yn-3-ols, a methyl substituent is superior to long alkyl chains as the 1,2-migration groups toward α-imino gold carbenes. For secondary prop-1-yn-3-ols, phenyl, vinyl, and cyclopropyl substituents are better than hydrogen as the migrating groups, obviating typical gold carbene reactions. DFT calculations have been performed to rationalize the observed C(1)-regioselectivity and the preferable cyclopropyl migration based on gold carbene pathways.
- Skaria, Manisha,More, Sayaji Arjun,Kuo, Tung-Chun,Cheng, Mu-Jeng,Liu, Rai-Shung
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supporting information
p. 3600 - 3608
(2020/03/04)
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- Alkynylation of aldehydes and ketones using the Bu4NOH/H 2O/DMSO catalytic composition: A wide-scope methodology
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The Favorsky reaction of a wide range of aldehydes and ketones with alkynes has been implemented under mild conditions (5-20 C). Using a Bu 4NOH/H2O/DMSO catalytic system, propargylic alcohols are formed cleanly in 39-93% (mostly 72-93%) yields and with ca. 100% selectivity. The method is suitable for aliphatic, aromatic, and heteroaromatic aldehydes and ketones, and for aliphatic, aromatic, and functionalized acetylenes. Thus, this represents the most general and efficient protocol to achieve the Favorsky reaction. Copyright
- Schmidt, Elena Yu.,Cherimichkina, Natalia A.,Bidusenko, Ivan A.,Protzuk, Nadezhda I.,Trofimov, Boris A.
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p. 4663 - 4670
(2014/08/05)
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- Pd(II)-catalyzed highly regio-and stereoselective assembly of C-C double bonds: An efficient method for the synthesis of 2,4-dihalo-1,3,5-trienes from alkynols
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A highly efficient method for the synthesis of 2,4-dihalo-1,3,5-trienes from alkynols was developed. This chemistry allows access to multiple conjugated double bonds in a single step with high stereoselectivity.
- Jiang, Huanfeng,Gao, Yang,Wu, Wanqing,Huang, Yubing
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supporting information
p. 238 - 241
(2013/03/13)
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- Stereoselective One-Pot synthesis of 1-Aminoindanes and 5,6-Fused azacycles using a Gold-Catalyzed Redox-Pinacol-Mannich-Michael cascade
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"Chemical Equation Presented" Just another Mannich Monday: A cascade intramolecular redox-pinacol-Mannich-Michael reaction sequence catalyzed by gold complexes can be used to generate a variety of structures including spirocycles, 1-aminoindanes, and 5,6-fused azabicycles that have a quaternary carbon center. The reaction is characterized by complete atom-economy, high diastereoselectivity, and remarkable efficiency through tandem reactions.
- Yeom, Hyun-Suk,Lee, Youngun,Jeong, Jaewon,So, Eunsoo,Hwang, Soojin,Lee, Ji-Eun,Lee, Shim Sung,Shin, Seunghoon
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supporting information; experimental part
p. 1611 - 1614
(2010/06/15)
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- Anti-AIDS agents. Part 62: Anti-HIV activity of 2′-substituted 4-methyl-3′,4′-di-O-(-)-camphanoyl-(+)-cis-khellactone (4-methyl DCK) analogs
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Four 4-methyl-3′,4′-di-O-(-)-camphanoyl-(+)-cis-khellactone (4-methyl DCK) analogs (7a-d) with different alkyl substituents at the 2′-position were synthesized and evaluated for inhibition of HIV-1 replication in H9 lymphocytes. 2′-Methyl-2′-ethyl-4-methyl DCK (7b) was more potent (EC50 = 0.22 μM, TI > 175) than the other three compounds (7a, 7c, and 7d), but significantly less potent than 4-methyl DCK (2, EC50 = 0.0059 μM, TI > 6600). Four 4-methyl-3′,4′- di-O-(-)-camphanoyl-(+)-cis-khellactone (4-methyl DCK) analogs (7a-d) with different alkyl substituents at the 2′-position were synthesized and evaluated for inhibition of HIV-1 replication in H9 lymphocytes. 2′-Methyl-2′-ethyl-4-methyl DCK (7b) was more potent (EC 50 = 0.22 μM, TI > 175) than the other three compounds (7a, 7c, and 7d), but significantly less potent than 4-methyl DCK (2, EC50 = 0.0059 μM, TI > 6600). The bioassay results indicated that the 2′-substituents had a strong effect on the anti-HIV activity, and gem-dimethyl substitution at the 2′-position was greatly preferable to larger alkyl substituents or hydrogen atoms.
- Zhang, Qian,Chen, Ying,Xia, Peng,Xia, Yi,Yang, Zheng-Yu,Yu, Donglei,Morris-Natschke, Susan L.,Lee, Kuo-Hsiung
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p. 5855 - 5857
(2007/10/03)
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- ETHYNYLATION PROCESS
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A process for the manufacture of an acetylenically unsaturated alcohol comprising reacting formaldehyde, an aldehyde or a ketone (a carbonyl compound) with acetylene in the presence of ammonia and an alkali metal hydroxide, the molar ratio of the alkali metal hydroxide to the carbonyl compound being less than 1 : 200. The reaction products, which depending on the starting carbonyl compound are propargyl alcohol or 1-monosubstituted or 1,1-disubstituted derivatives thereof, are of use as intermediates in the synthesis of many useful end products, inter alia in the field of vitamins and carotenoids.
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- Carbon-carbon bond formation in regio- and stereoselective palladium-catalyzed cyclization of allene-substituted conjugated dienes
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Regio- and stereoselective palladium-catalyzed reactions of allene-substituted 1,3-dienes 1 in acetic acid at room temperature lead to cyclization with formation of a carbon-carbon bond between the middle carbon of the allene and the terminal carbon of the 1,3-diene. Two different types of reactions, both that constitute 1,4-carboacetoxylations of the 1,3-diene, have been developed. In one of the reactions, Pd(II) catalyzes the oxidation of 1 to bicyclic compounds 2, and in the other, Pd(0) catalyzes the transformation of 1 to bicyclic compounds 3. The products 2 are useful for further synthetic tr0nsformations and undergo Diels-Alder reactions with dienophiles to give polycyclic ring systems.
- Loefstedt, Joakim,Franzen, Johan,Baeckvall, Jan-E.
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p. 8015 - 8025
(2007/10/03)
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- REACTIONS OF NITROGEN NUCLEOPHILES WITH 1-BROMOALLENES: REGIOSELECTIVE SYNTHESIS OF PROPARGYLAMINES
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The results of a study on the reactivity of 3-alkyl- and 3,3-dialkyl-1-bromo-1,2-dienes 2 towards nitrogen nucleophiles, such as aqueous ammonia, lithium amide, aliphatic and aromatic amines allowed us to propose new methods for the synthesis of propargylamines, 1, with an available acetylenic hydrogen.The regio- and the stereoselectivity of these reactions are examined and possible mechanisms are discussed.
- Geri, Roberto,Polizzi, Carmela,Lardicci, Luciano,Caporusso, Anna Maria
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p. 241 - 248
(2007/10/02)
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- The reaction of some propargyl alcohols with benzeneselenenyl chloride
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The reaction of benzeneselenenyl chloride with twenty-two propargyl alcohols in methylene chloride solution is reported.Products of both Markownikoff and anti-Markownikoff regiochemistry are formed in an anti stereospecific manner.The regioselectivity or specificity is found to be very dependent upon the nature of the substituents geminal to the alcoholic moiety.In general the presence of bulky substituents geminal to the alcoholic moiety tend to favour formation of the anti-Markownikoff adduct under conditions of kinetic control.The Markownikoff adducts are found to be favoured thermodynamically.
- Garratt, Dennis G.,Beaulieu, Pierre L.,Morisset, Veronique M.
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p. 927 - 934
(2007/10/02)
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- Hydroformylation of mono-α-olefins and mono-α-acetylenes
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This invention relates to improvements in certain catalytic reactions, namely, hydrogenation, hydroformylation and carbonylation reactions.
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