- Reductive Cleavage of Propargylic Ethers with Alkali Metal: Application to the Synthesis of Allenylboronates
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Treatment of propargylic ethers with sodium dispersion in the presence of lithium iodide results in the generation of the corresponding carbanion species via cleavage of the propargylic C-O bond. The anionic species react with trimethoxyborane to yield th
- Koyama, Shunsuke,Saito, Hayate,Takahashi, Fumiya,Yorimitsu, Hideki
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supporting information
p. 8590 - 8594
(2021/11/17)
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- Synthesis and Functionalization of Allenes by Direct Pd-Catalyzed Organolithium Cross-Coupling
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A palladium-catalyzed cross-coupling between in situ generated allenyl/propargyl-lithium species and aryl bromides to yield highly functionalized allenes is reported. The direct and selective formation of allenic products preventing the corresponding isomeric propargylic product is accomplished by the choice of SPhos or XPhos based Pd catalysts. The methodology avoids the prior transmetalation to other transition metals or reverse approaches that required prefunctionalization of substrates with leaving groups, resulting in a fast and efficient approach for the synthesis of tri- and tetrasubstituted allenes. Experimental and theoretical studies on the mechanism show catalyst control of selectivity in this allene formation.
- Casti?eira Reis, Marta,Feringa, Ben L.,Mateos-Gil, Jaime,Mondal, Anirban
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supporting information
p. 7823 - 7829
(2020/03/24)
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- Enabling the Rearrangement of Unactivated Allenes to 1,3-Dienes by Use of a Palladium (0)/Boric Acid System
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A redox neutral rearrangement of an allene to a 1,3-diene by means of a unique palladium hydride complex is reported. The palladium hydride complex is generated from a simple Pd 0 source and boric acid [B(OH) 3 ], which is typically identified as a waste by-product of the Suzuki-Miyaura reaction. A mechanism for this transformation using this novel palladium hydride complex is presented; using a direct sample loop and flow injection ESI-HRMS analysis we have detected and identified key π-allylpalladium complexes that support the addition of the palladium hydride complex to the allene.
- Al-Jawaheri, Yassir,Turner, Matthew,Kimber, Marc C.
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supporting information
p. 2329 - 2336
(2018/06/15)
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- Synthesis of 1,3-Dienes via a Sequential Suzuki-Miyaura Coupling/Palladium-Mediated Allene Isomerization Sequence
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We report a facile method for the synthesis of 1,3-dienes by a sequential process consisting of a palladium-catalyzed, base-free, Suzuki-Miyaura coupling/isomerization sequence. This sequence couples boronic acids with propargyl alcohols, generating the requisite allene in situ, followed by conversion of the unactivated allene to its 1,3-diene via a hydro-palladation/dehydro-palladation process. This process is general for a range of boronic acids, including boronic acids with electron-donating and -withdrawing groups, as well as heteroarylboronic acids. Key to this process is the boric acid byproduct of the base-free Suzuki-Miyauru coupling, which generates the required palladium-hydrido complex [H-PdII-OB(OH)2] required for the isomerization.
- Al-Jawaheri, Yassir,Kimber, Marc C.
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supporting information
p. 3502 - 3505
(2016/07/23)
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- Synthesis of Allenes by Catalytic Coupling of Propargyl Carbonates with Aryl Iodides in the Presence of Diboron Species
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Bimetallic copper-/palladium-catalyzed multicomponent reaction of propargyl carbonates, aryl iodides, and diboron species was studied. This procedure can be used for synthesis of di-, tri-, and tetra-substituted allenes. Using diboronic acid, the reaction
- Yang, Yuzhu,Szabó, Kálmán J.
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p. 250 - 255
(2016/01/15)
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- SAMDI Mass Spectrometry-Enabled High-Throughput Optimization of a Traceless Petasis Reaction
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Development of the self-assembled monolayer/MALDI mass spectrometry (SAMDI) platform to enable a high-throughput optimization of a traceless Petasis reaction is described. More than 1800 unique reactions were conducted simultaneously on an array of self-assembled monolayers of alkanethiolates on gold to arrive at optimized conditions, which were then successfully transferred to the solution phase. The utility of this reaction was validated by the efficient synthesis of a variety of di- and trisubstituted allenes.
- Diagne, Abdallah B.,Li, Shuheng,Perkowski, Gregory A.,Mrksich, Milan,Thomson, Regan J.
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supporting information
p. 658 - 662
(2015/11/17)
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- Gold-catalyzed isomerization of unactivated allenes into 1,3-dienes under ambient conditions
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We have developed a gold-catalyzed isomerization of unactivated allenes into 1,3-dienes with nitrosobenzene as an additive. This reaction proceeded almost exclusively at room temperature for highly substituted allenes. The utility of this reaction is manifested by the development of one-pot [4+2]-cycloaddition of allenes and reactive alkenes.
- Ting, Chun-Ming,Hsu, Yi-Ling,Liu, Rai-Shung
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p. 6577 - 6579
(2012/07/31)
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- Coupling of n-tosylhydrazones with terminal alkynes catalyzed by copper(i): Synthesis of trisubstituted allenes
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The easy way to allenes: An operationally simple reaction under mild conditions has led to the direct formation of trisubstituted allenes (see scheme; Ts=4-toluenesulfonyl). An unprecedented copper-carbene migratory insertion process seems to take place,
- Xiao, Qing,Xia, Ying,Li, Huan,Zhang, Yan,Wang, Jianbo
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p. 1114 - 1117
(2011/04/16)
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- Gold(I)-catalyzed rearrangement of propargyl benzyl ethers: A practical method for the generation and in situ transformation of substituted allenes
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A series of benzyl propargyl ethers react with a gold(I) catalyst to furnish variously substituted allenes via a 1,5-hydride shift/fragmentation sequence. This transformation is rapid and practical. It can be performed under very mild conditions (room temperature or 60 °C) using terminal as well as substituted alkyne substrates bearing a primary, secondary, or tertiary benzyl ether group. The allenes thus formed can be reacted in situ with an internal or external nucleophile, corresponding to an overall reductive substitution process, to produce more functionalized compounds.
- Bolte, Benoit,Odabachian, Yann,Gagosz, Fabien
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supporting information; experimental part
p. 7294 - 7296
(2010/08/05)
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- Generation of allenic/propargylic zirconium complexes and subsequent cross-coupling reactions: A facile synthesis of multisubstituted allenes
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(Chemical Equation Presented) The β-alkoxide elimination reaction of propargylic ether with Negishi reagent leads to allenes and/or alkynes after hydrolysis. The product distribution is highly dependent on the substitution pattern of starting propargylic
- Zhang, Hao,Fu, Xiaoping,Chen, Jingjin,Wang, Erjuan,Liu, Yuanhong,Li, Yuxue
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supporting information; experimental part
p. 9351 - 9358
(2010/03/04)
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- Palladium-catalyzed cross-coupling reaction of triorganoindium reagents with propargylic esters
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Triorganoindium reagents (R3In) react with propargylic esters under palladium catalysis via an SN2′ rearrangement to afford allenes in good yields and with high regioselectivity. The reaction proceeds smoothly at room temperature wit
- Riveiros, Ricardo,Rodriguez, David,Sestelo, Jose Perez,Sarandeses, Luis A.
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p. 1403 - 1406
(2007/10/03)
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- (Cycloalkylidenemethyl)triphenylphosphonium Salts as Versatile Intermediate Reagents
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The (cycloalkylidenemethyl)triphenylphosphonium salts 2b-d were synthesized in high yields by phenylselenylation of (cycloalkylmethylene)triphenylphosphoranes with benzeneselenenyl bromide to the triphenylphosphonium salts 1b-d and subsequent oxidative elimination of the phenylseleno moiety, while the synthesis of the (cyclopropylidenemethyl)triphenylphosphonium salt 2a was unsuccessful.Hydrolysis of 2b-d in aqueous THF and methanol containing sodium hydroxide was studied.The reactions of the (cyclohexylidenemethyl)phosphonium salt 2d and 1.1 equiv of butyllithium with aldehydes 9 gave alkenylcyclohexenes 10d-f in 56-81percent yields, whereas similar reactions using 1.5 equiv and 2 equiv of butyllithium produced allenes 11d-f as major products together with small amounts of 10d,e.Similar reactions of the (cyclopentylidenemethyl)phosphonium salt 2c and butyllithium with 9 gave alkenylcyclopentenes 10a-c in 56-80percent yields, regardless of the amount of butyllithium used.The formation mechanism of 10 and 11 was discussed.
- Minami, Toru,Shikita, Shoji,So, Shuichiro,Nakayama, Minoru,Yamamoto, Izumi
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p. 2937 - 2942
(2007/10/02)
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- PALLADIUM-CATALYZED REDUCTION OF PROPARGYLIC ACETATES WITH SmI2. A MILD AND CONVENIENT METHOD FOR THE PREPARATION OF ALLENES
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A highly regioselective reduction of propargylic acetates has been attained by using SmI2 and catalytic Pd(0) in the presence of 2,4-dimethyl-3-pentanol affording various types of allenes in high yields.
- Tabuchi, Takanori,Inanaga, Junji,Yamaguchi, Masaru
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p. 5237 - 5240
(2007/10/02)
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- Preparation of Allenes from Geminal Dibromo Olefins and Aldehyds
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The carbonyl carbons of ketones (acetone, cyclohexanone) and aldehydes (propanal, 2,2-dimethylpropanal, acrolein, benzaldehyde, p-methoxybenzaldehyde) are joined through a single carbon atom (originating from carbon tetrabromide) to give trisubstituted al
- Haessig, Robert,Seebach, Dieter,Siegel, Herbert
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p. 1877 - 1884
(2007/10/02)
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