- Cobalt-Catalyzed Intermolecular Markovnikov Hydroamination of Nonactivated Olefins: N2-Selective Alkylation of Benzotriazole
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Cobalt-catalyzed Markovnikov-selective hydroamination of nonactivated olefins was developed. Hydrogen atom transfer from a catalytically generated cobalt(III)-hydride complex to the olefins proceeded regioselectively, and the nucleophilic addition of benzotriazoles occurred selectively at their N2-positions. The synthetic utility of the obtained N2-alkylated benzotriazoles as stable amine protecting groups under various reaction conditions was demonstrated, and the products were also transformed into primary amines by zinc-mediated reduction.
- Yahata, Kenzo,Kaneko, Yuki,Akai, Shuji
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p. 598 - 603
(2020/02/04)
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- Renewable Polyethers via GaBr3-Catalyzed Reduction of Polyesters
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Herein, a novel approach is reported for the synthesis of medium- and long-chain aliphatic polyethers 2 based on the GaBr3-catalysed reduction of polyesters 1 with TMDS as the reducing agent. Thus, various linear and branched aliphatic polyesters 1 were prepared and systematically investigated for this reduction strategy, demonstrating the applicability and versatility of this new polyether synthesis protocol. Medium- and long-chain chain polyethers were obtained from the respective polyesters without or with minor chain degradation, whereas short-chain polyesters, such as poly-l-lactide 1 i and poly[(R)-3-hydroxybutanoate] 1 j, showed major chain degradation. In this way, previously unavailable and uncommon polyethers were obtained and studied.
- Dannecker, Patrick-Kurt,Biermann, Ursula,von Czapiewski, Marc,Metzger, Jürgen O.,Meier, Michael A. R.
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supporting information
p. 8775 - 8779
(2018/07/14)
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- Synthesis of racemic lipid unit of the nucleoside antibiotic, liposidomycin-B
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The lipid part (10) of liposidomycin-B has been synthesised through functional manipulation of undecenoic acid (1) which involves chain extension via Reformatsky reaction and introduction of the methyl branching through organocuprate coupling.
- Kalyanakumar,Chadha,Chattopadhyay,Mamdapur
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p. 356 - 358
(2007/10/03)
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- Reaction of Organic Halides with Chlorotris(triphenylphosphine)cobalt(I)
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Reaction of various types of organic halides with a monovalent cobalt complex, chlorotris(triphenylphosphine)cobalt(I) is described.Reaction of benzylic monohalides, dihalides and trihalides with CoCl(Ph3P)3 gave a coupling product with formation of a carbon-carbon single bond, double bond and triple bond, respectively, under mild and non-basic conditions.Dehalogenation of non-benzylic vicinal dihalides with the reagent took place cleanly to give an olefin in high yield.Reductive coupling of allylic halides using the reagent afforded regioselectively a 1,5-diene with retention of the stereochemistry of the carbon-carbon double bond of the allylic halides used.By using this reaction, (E,E,E,E)-squalene was stereospecifically synthesized from (E,E)-farnesyl bromide.Reaction of halohydrins with CoCl(Ph3P)3 gave exclusively a ketone in the presence of an amine or olefin through an alkylcobalt intermediate.A 1,2-hydrogen shift is involved in this reaction.Keywords - chlorotris(triphenylphosphine)cobalt(I); coupling reaction; benzylic halides; allylic halides; synthesis of 1,5-diene; squalene; halohydrin; ketone synthesis.
- Momose, Den-ichi,Iguchi, Kazuo,Sugiyama, Toshikazu,Yamada, Yasuji
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p. 1840 - 1853
(2007/10/02)
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- REACTION OF BROMOHYDRINS WITH CHLOROTRIS(TRIPHENYLPHOSPHINE)COBALT(I)
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Bromohydrins were converted into ketones in high yields by the reaction with chlorotris(triphenylphosphine)cobalt(I) in the presence of amine or olefin.A probable path-way for the formation of ketones from bromohydrins was also described.
- Momose, Den-ichi,Yamada, Yasuji
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p. 2669 - 2672
(2007/10/02)
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- INSECT PHEROMONES AND THEIR ANALOGS III. SYNTHESIS OF THE SEX ATTRACTANTS OF SOME LEPIDOPTERA
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A new route to the synthesis of a number of attractants of Lepidoptera (Argyrotaenia velutinana, Mamestra configurata, and Lycorea ceres ceres) have been developed.These substances are acetates of enols with the cis configuration: tetradec-11-en-1-ol, hexadec-11-en-1-ol, and octadec-11-en-1-ol, respectively.The constants of the substances obtained agree completely with those given in the literature.The method is based on the coupling of the C3, C5, and C7 aldehydes with methyl 11-bromoundecanoate (I) by the Wittig reaction.To obtain compound (I) from methyl undeca-2E,5E,10-trienoate or methyl undeca-10-enoate we used hydroboration according to Brown followed by hydrogenation and bromination of the alcohol obtained.The advantage of this method is the use as starting materials of esters of unsaturated acids readily obtained by the homogeneous catalytic co-oligomerization of 1,3-dienes with acrylates.
- Dzhemilev, U. M.,Balezina, G. G.,Volkova, L. A.,Krivonogov, V. P.,Tolstikov, G. A.
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