- Alkylation of Terminal Alkynes under Zinc Lewis Acid Catalysis and Its Mechanistic Studies
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With a zinc Lewis acid catalyst and proton sponge in toluene, terminal alkynes were found to undergo the alkylation by alkyl triflates to provide unsymmetrical internal alkynes. This is the first example that a simple alkyl chain other than benzylic and norbornyl units can be introduced onto the alkynyl carbon atom under Lewis acid catalysis. Mechanistic studies revealed that the activation of the alkyne by the zinc Lewis acid and proton sponge is the trigger of the reaction to give a monoalkynylzinc species, which successively reacts with the alkyl triflate to afford the internal alkyne. A radical pathway is unlikely in this system. (Figure presented.).
- Osano, Mana,Kida, Takeru,Yonekura, Kyohei,Tsuchimoto, Teruhisa
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supporting information
p. 2825 - 2831
(2019/04/13)
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- New type formation of 1,3-enynes (or internal alkynes) via coupling of organoboranes with alkynylcopper compounds mediated by copper(II)
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The copper(II) - mediated coupling reaction of alkenyl-dialkyl- or trialkyl-boranes with alkynylcopper compounds (generated in situ), in the presence of appropriate solvents and a small amount of water, gives (E)-1,3-enynes (or disubstituted alkynes) with various functional groups in reasonable yields.
- Masuda, Yuzuru,Murata, Miki,Sato, Kaname,Watanabe, Shinji
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p. 807 - 808
(2007/10/03)
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- Selective Coupling Reactions of Alkynyl(phenyl)iodonium Tosylates with Alkynylcopper Reagents
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Alkynyl(phenyl)iodonium tosylates react with mixed cuprates coordinated by alkynyl components to give unsymmetrical diacetylenes selectively; the coupling reaction with dialkylcuprates afforded substituted alkynes.
- Kitamura, Tsugio,Tanaka, Toshimasa,Taniguchi, Hiroshi,Stang, Peter J.
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p. 2892 - 2893
(2007/10/02)
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- Preparation of (Z)-Alkenes, Ketones, and Alkynes via Trialkyltin Chloride Induced Intramolecular Transfer Reaction of Lithium 1-Alkynyltrialkylborates. Stereoselective Synthesis of the Sex Pheromones of the Douglas Fir Tussock Moth, the Gipsy Moth, and the Wild Silkmoth Antheraea poly...
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Trialkyltin chloride was used to induce selective migration of a primary alkyl group from the boron atom to the adjacent acetylenic carbon atom of lithium 1-alkynyltrialkylborate complexes derived from B-alkyl-9-borabicyclononanes and 1-lithio-1-alkynes.Protonolysis of the resultant olefinic intermediate substituted with boron and tin functionalities on the adjacent vinyl carbon atoms provided the corresponding (Z)-alkene.Oxidation or iodination afforded the corresponding ketone or alkyne, respectively.The high selectivity of 9-borabicyclononane as ahydroborating agent toward the terminal double bond allowed easy incorporation of internal double bond and triple bond into the alkyl group of the starting B-alkyl-9-borabicyclononane.Various types of diene, enyne, enone, ynone and diyne were synthesized.These reactions were also successfully adopted for the stereoselective synthesis of sex pheromones of the Douglas fir tussock moth, the gypsy moth, and the wild silkmoth Antheraea polyphemus.
- Wang, Kung K.,Chu, Kai-Hsuan
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p. 5175 - 5178
(2007/10/02)
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- Reactions with Phosphine Alkylenes, XLII. A Sequence for the Preparation of Acetylenes Starting from Carboxylic Chlorides and Phosphorus Ylides via 1,2-Diketones.
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Phosphorus ylides 1 and carboxylic chlorides 2 react with transylidation to give acyl ylides 3 which are oxidized with the adduct of ozone to triphenyl phosphite to yield 1,2-diketones 5.These are converted into the bis(hydrazones) 6 which are oxidized with O2/CuCl in pyridine giving acetylenes 7.
- Bestmann, Hans Juergen,Kumar, Kamlesh,Kisielowski, Lothar
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p. 2378 - 2382
(2007/10/02)
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- DEFLUORINATIVE COUPLING REACTIONS OF gem-DIFLUOROOLEFINS WITH ORGANOLITHIUM REAGENTS. NOVEL, FACILE METHODS FOR CHAIN ELONGATIONS OF ALDEHYDES LEADING TO AMIDES, ACETYLENES, AND KETONES
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Three types of coupling reactions of gem-difluoroolefins derived easily from aldehydes with lithium reagents (R'Li and R'2NLi) are described which constitute the facile procedures for conversions of aldehydes (RCHO) to amides (RCH2CONR'2), acetylenes (RCCR'), and ketones (RCH2COR').
- Hayashi, Sei-ichi,Nakai, Takeshi,Ishikawa, Nobuo
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p. 935 - 938
(2007/10/02)
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- REACTION OF TRIALKYLBORANE WITH 1-ALKYNE AND LEAD(IV) ACETATE, A NEW REGIOSPECIFIC AND STEREOSPECIFIC ONE-POT SYNTHESIS OF ENOL ACETATES
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In the reaction of trialkylborane with 1-alkyne and lead(IV) acetate in hexane, one of the alkyl groups of trialkylborane migrated to the terminal carbon atom of the triple bond, giving regiospecifically an internal enol acetate and an internal alkyne as the main reaction products.The former compound had (Z)-configuration.
- Masuda, Yuzuru,Hoshi, Masayuki,Arase, Akira
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p. 413 - 416
(2007/10/02)
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