- Copper-catalyzed aerobic oxidative transformation of ketone- Derived N-tosyl hydrazones: An entry to alkynes
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A novel strategy involving Cu-catalyzed oxidative transformation of ketone-derived hydrazone moiety to various synthetic valuable internal alkynes and diynes has been developed. This method features inexpensive metal catalyst, green oxidant, good functional group tolerance, high regioselectivity and readily available starting materials. Oxidative deprotonation reactions were carried out to form internal alkynes and symmetrical diynes. Cross-coupling reactions of hydrazones with halides and terminal alkynes were performed to afford functionalized alkynes and unsymmetrical conjugated diynes. A mechanism proceeding through a Cu-carbene intermediate is proposed for the CC triple bond formation.
- Li, Xianwei,Liu, Xiaohang,Chen, Huoji,Wu, Wanqing,Qi, Chaorong,Jiang, Huanfeng
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p. 14485 - 14489
(2015/02/05)
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- Synthesis of bicyclic N,N-enaminals by cyclization of alk-4-ynals with aliphatic diamines in DMSO upon treatment with KOH
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A cyclization of alk-4-ynals with aliphatic diamines in DMSO upon treatment with KOH was found to lead to bicyclic N,N-enaminals. The studies of this reaction showed that 1,3-diaminopropane and N-methyl-1,3-diaminopropane gave (E)-6-(arylmethylidene)octahydropyrrolo[1,2-a]pyrimidines in 45 - 78% yields, whereas 1,2-diaminoethane gave 5-(arylmethylidene)hexahydropyrrolo[1,2-a] imidazoles as mixtures of E- and Z-isomers in up to 75% total yield. The mechanism of these new cascade cyclization reactions includes formation of the equilibrium mixtures of imines and cyclic aminals with subsequent intramolecular hydroamination of the triple bond having considerable ionic character.
- Gvozdev,Shavrin,Nefedov
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p. 2430 - 2437
(2014/11/08)
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- Copper-catalyzed nucleophilic trifluoromethylation of propargylic halides
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Reactions of propargylic halides with trifluoromethyltrimethylsilane in the presence of a catalytic amount of copper(i) thiophene-2-carboxylate (CuTC) have been found to give the corresponding trifluoromethylated products in good to high yields with a hig
- Miyake, Yoshihiro,Ota, Shin-Ichi,Shibata, Masashi,Nakajima, Kazunari,Nishibayashi, Yoshiaki
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supporting information
p. 7809 - 7811
(2013/09/02)
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- Copper(I)-catalyzed regio- and chemoselective single and double addition of nucleophilic silicon to propargylic chlorides and phosphates
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Copper(I)-catalyzed propargylic substitution of linear precursors with (Me2PhSi)2Zn predominantly yields the γ isomer independent of the propargylic leaving group. The thus formed allenylic silane reacts regioselectively with another equivalent of (Me2PhSi) 2Zn, yielding a bifunctional building block with allylic and vinylic silicon groups. The reaction rates of both steps are well-balanced for chloride (γ:α ≥ 99:1) where the propargylic displacement occurs quantitatively prior to the addition step. Substitutions of α-branched propargylic phosphates are also reported.
- Hazra, Chinmoy K.,Oestreich, Martin
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supporting information; experimental part
p. 4010 - 4013
(2012/10/08)
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- Development of a catalytic platform for nucleophilic substitution: Cyclopropenone-catalyzed chlorodehydration of alcohols
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Cyclopropenone makes the switch: 2,3-Bis-(p-methoxyphenyl)cyclopropenone is a highly efficient catalyst for the chlorodehydration of 20 diverse alcohol substrates (see scheme; X=Cl). With oxalyl chloride as catalytic activator, this nucleophilic substitution proceeded through cyclopropenium-activated intermediates and resulted in complete stereochemical inversion in substrates with chiral centers.
- Vanos, Christine M.,Lambert, Tristan H.
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supporting information; experimental part
p. 12222 - 12226
(2012/02/02)
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- Copper(I)-catalyzed regioselective propargylic substitution involving Si-B bond activation
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The silicon nucleophile generated by copper(I)-catalyzed Si-B bond activation allows several γ-selective propargylic substitutions. The regioselectivity (γ:α ratio) is strongly dependent on the propargylic leaving group. Chloride is superior to oxygen leaving groups in linear substrates (γ:α > 99:1), and it is only the phosphate group that also shows promising regiocontrol (γ:α = 90:10). That leaving group produces superb γ-selectivity (γ:α > 99:1) in α-branched propargylic systems, and enantioenriched substrates react with excellent central-to-axial chirality transfer.
- Vyas, Devendra J.,Hazra, Chinmoy K.,Oestreich, Martin
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supporting information; experimental part
p. 4462 - 4465
(2011/10/08)
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- A new method for the preparation of 1,5-diynes. Synthesis of (4E,6Z,10Z)-4,6,10-hexadecatrien-1-ol, the pheromone component of the cocoa pod borer moth Conopomorpha cramerella
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(Figure Presented) A new method for the synthesis of 1,5-diynes, from the reaction of 1,3-dilithiopropyne and propargyl chlorides, was developed. This new methodology was used to prepare (4E,6Z,10Z)-4,6,10-hexadecatrien-1-ol, one of the pheromone componen
- Pereira, Alban R.,Cabezas, Jorge A.
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p. 2594 - 2597
(2007/10/03)
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- 2-amino-1,3-propanediol compound and immunosuppressant
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2-Amino-1,3-propanediol compounds of the formula (I) STR1 wherein R is an optionally substituted straight- or branched carbon chain, an optionally substituted aryl, an optionally substituted cycloalkyl or the like, and R2, R3, R4 and R5 are the same or different and each is a hydrogen, an alkyl, an aralkyl, an acyl or an alkoxycarbonyl, pharmaceutically acceptable salts thereof and immunosuppressants comprising these compounds as active ingredients. The 2-amino-1,3-propanediol compounds of the present invention show immunosuppressive action and are useful for suppressing rejection in organ or bone marrow tranplantation, prevention and treatment of autoimmune diseases or as reagents for use in medicinal and pharmaceutical fields.
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- Study of the decomposition of halo adducts derived from propargylic phenylselenides. Intermediate formation of haloallenes
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The decomposition of bromo- and chloro-adducts, derived from propargylic phenylselenides, leads to 1,3-dihalo 2-phenylseleno propene derivatives through intermediate formation of haloallenes.
- Duclos, Jean-Francois
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p. 2627 - 2630
(2007/10/02)
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- Electrochemical Reduction of Phenylpropadiene at Mercury Cathodes in Dimethylformamide: Isomerization of the Allene to 1-Phenyl-1-propyne
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Polarograms and cyclic voltammograms exhibit two waves for reduction of phenylpropadiene at a mercury electrode in dimethylformamide containing tetra-n-butylammonium perchlorate; the first wave signals reduction of phenylpropadiene to 1-phenyl-1-propene and the second wave is attributable to reduction of 1-phenyl-1-propene to 1-phenylpropane.However, the first wave is abnormally small because phenylpropadiene undergoes substantial rearrangement to 1-phenyl-1-propyne, which is reducible to 1-phenylpropane at nearly the same potential as 1-phenyl-1-propene.Controlled-pot ential electrolyses of phenylpropadiene, 1-phenyl-1-propene, and 1-phenyl-1-propyne at mercury pool cathodes have verified the processes elucidated by means of polarography and cyclic voltammetry.In the presence of diethyl malonate (a proton donor), base-catalyzed isomerization of phenylpropadiene to 1-phenyl-1-propyne is blocked totally; at a potential corresponding to the first wave for reduction of phenylpropadiene, electrolysis products are trans-1-phenyl-1-propene, cis-1-phenyl-1-propene, and 1-phenyl-2-propene, whereas 1-phenylpropane and 1-phenyl-2-propene are obtained at a potential on the second reduction wave for phenylpropadiene.
- Chen, Tsu-yu Raymond,Anderson, Mark R.,Grossman, Steven,Peters, Dennis G.
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p. 1231 - 1236
(2007/10/02)
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- FREE RADICAL REARRANGEMENTS OF ORGANOCOBALOXIMES: ALKYNYL TO CYCLOALKYLIDENE AND HEXENYL TO CYCLOPENTYLMETHYL
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Under irradiation by tungsten light in pyridine solution, several substituted alkylcobaloximes undergo rearrangement to more stable substituted alkyl- or alkenyl-cobaloximes.When the same reactions are carried out in the presence of carbon tetrachloride or chloroform, no rearranged organobaloximes are obtained, but a variety of organic products are obtained derived from the interception of transient organic radicals by the halogenated solvent.The rearrangements are rationalised in terms of a reversible homolysis of the carbon-cobalt bond, rearrangement of the organic radical and recapture by the cobalt(II) fragment to give complexes that are more stable to irradiation than their precursors.
- Bougeard, Peter,Cooksey, Christopher J.,Johnson, Michael D.,Lewin, Melanie J.,Mitchell, Stewart,Owens, Paul A.
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p. 349 - 358
(2007/10/02)
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