- Generation of a geminal dicarbenoid of chromium: Formation of allenes from terminal alkenes in one-pot
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Treatment of CCl4 with 4 equiv of CrCl2 in THF generates a geminal dicarbenoid of chromium by reduction of two of the chlorine atoms of CCl4, and the dicarbenoid species selectively reacts with terminal olefins to give cyclopropylidene carbenoids, which readily decompose to allenes.
- Takai, Kazuhiko,Kokumai, Ryo,Toshikawa, Shota
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- Preparation of (E)-1,3-Enyne Derivatives through Palladium Catalyzed Hydroalkynylation of Allenes
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A general and efficient palladium catalyzed hydroalkynylation of allenes was developed to produce synthetically versatile (E)-1,3-enyne derivatives with high regio- and stereoselectivity. This catalytic system proceeded under mild conditions and was compatible with a broad range of substrates, especially for allenes without electron-bias groups. This work further broadens the synthetic potential of these scaffolds in organic synthesis and medicinal chemistry.
- Liu, Zhi-Kai,Yang, Ying,Zhan, Zhuang-Ping
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supporting information
p. 1589 - 1597
(2022/01/20)
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- Addition of Chloroprene Grignards to Aromatic Aldehydes: Synthesis of Homoallenyl Alcohols
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A general procedure for the one-pot synthesis of racemic homoallenyl alcohols from the corresponding aldehyde and chloroprene-derived Grignards is described. Employing bis[2-dimethylaminoethyl]ether (BDMAEE) as an additive at low temperatures shifts the selectivity of the chloroprene Grignard addition to aldehydes such that it is almost exclusive toward allene formation. In a set of follow-up experiments, simple and more elaborate methods for further derivatization have been demonstrated, allowing quick access to more complex structures.
- Geissler, Arne G. A.,Breit, Bernhard
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supporting information
p. 2621 - 2625
(2021/04/12)
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- Palladium-Catalyzed Carbonylative Four-Component Synthesis of β-Perfluoroalkyl Amides
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Transition-metal-catalyzed multicomponent carbonylation is one of the most efficient strategies to construct carbonyl-containing compounds. Herein, a palladium-catalyzed four-component perfluoroalkylation/aminocarbonylation of unactivated alkenes with per
- Geng, Hui-Qing,Wu, Xiao-Feng,Zhang, Youcan
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supporting information
p. 17682 - 17687
(2021/10/25)
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- Migratory Hydrogenation of Terminal Alkynes by Base/Cobalt Relay Catalysis
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Migratory functionalization of alkenes has emerged as a powerful strategy to achieve functionalization at a distal position to the original reactive site on a hydrocarbon chain. However, an analogous protocol for alkyne substrates is yet to be developed. Herein, a base and cobalt relay catalytic process for the selective synthesis of (Z)-2-alkenes and conjugated E alkenes by migratory hydrogenation of terminal alkynes is disclosed. Mechanistic studies support a relay catalytic process involving a sequential base-catalyzed isomerization of terminal alkynes and cobalt-catalyzed hydrogenation of either 2-alkynes or conjugated diene intermediates. Notably, this practical non-noble metal catalytic system enables efficient control of the chemo-, regio-, and stereoselectivity of this transformation.
- Liu, Bingxue,Liu, Qiang,Liu, Xufang
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supporting information
p. 6750 - 6755
(2020/03/13)
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- Enantioselective Copper-Catalyzed Three-Component Carboboronation of Allenes: Access to Functionalized Dibenzo [b,f][1,4]oxazepine Derivatives
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A copper-catalyzed enantioselective three-component difunctionalization of allenes with seven-membered cyclic imines and bis(pinacolato)diboron (B2(Pin)2) to approach functionalized dibenzo[b,f][1,4]oxazepine derivatives is developed. The chiral products are obtained in up to 81% yield, >20:1 dr, and 98% ee when either a chiral diphosphine ligand or a chiral ferrocenyl-based P,N-ligand is used. Furthermore, the reaction exhibits reversed diastereoselectivities when the chiral diphosphine ligand and the chiral P,N-ligand are used respectively. (Figure presented.).
- Deng, Hao,Meng, Ziwei,Wang, Sifan,Zhang, Zheming,Zhang, Yaqi,Shangguan, Yu,Yang, Fazhou,Yuan, Dekai,Guo, Hongchao,Zhang, Cheng
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p. 3582 - 3587
(2019/07/17)
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- Copper-Catalyzed Propargylic Reduction with Diisobutylaluminum Hydride
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A mild and efficient method for the synthesis of allenes through selective copper-catalyzed hydride addition to propargylic chlorides using commercially available diisobutylaluminum hydride has been developed. This transformation, which is promoted by a readily accessible N-heterocyclic carbene-copper complex, provides a wide range of new and versatile functionalized allenes in good to excellent yields with high regio- A nd stereoselectivities.
- Kim, Yuna,Lee, Hanseul,Park, Sunga,Lee, Yunmi
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supporting information
p. 5478 - 5481
(2018/09/13)
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- Co(III)-Catalyzed, Internal and Terminal Alkyne-Compatible Synthesis of Indoles
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A Co(III)-catalyzed, internal and terminal alkyne-compatible indole synthesis protocol is reported herein. The N-amino (hydrazine) group imparts distinct, diverse reactivity patterns for directed C-H functionalization/cyclization reactions. Notable synthetic features include regioselectivity for a meta-substituted arylhydrazine, regioselectivity for a chain-branched terminal alkyne, formal incorporation of an acetylenic unit through C2-desilylation on a C2-silylated indole derivative, formal inversion of regioselectivity through consecutive C3-derivatization and C2-desilylation processes, and formal bond migration for a linear-chain terminal alkyne.
- Zhou, Shuguang,Wang, Jinhu,Wang, Lili,Chen, Kehao,Song, Chao,Zhu, Jin
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supporting information
p. 3806 - 3809
(2016/08/16)
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- Highly Regio- and Enantioselective Alkoxycarbonylative Amination of Terminal Allenes Catalyzed by a Spiroketal-Based Diphosphine/Pd(II) Complex
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An enantioselective alkoxycarbonylation-amination cascade process of terminal allenes with CO, methanol, and arylamines has been developed. It proceeds under mild conditions (room temperature, ambient pressure CO) via oxidative Pd(II) catalysis using an aromatic spiroketal-based diphosphine (SKP) as a chiral ligand and a Cu(II) salt as an oxidant and affords a wide range of α-methylene-β-arylamino acid esters (36 examples) in good yields with excellent enantioselectivity (up to 96% ee) and high regioselectivity (branched/linear > 92:8). Preliminary mechanistic studies suggested that the reaction is likely to proceed through alkoxycarbonylpalladation of the allene followed by an amination process. The synthetic utility of the protocol is showcased in the asymmetric construction of a cycloheptene-fused chiral β-lactam.
- Liu, Jiawang,Han, Zhaobin,Wang, Xiaoming,Wang, Zheng,Ding, Kuiling
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p. 15346 - 15349
(2015/12/26)
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- Highly regio- and stereoselective synthesis of alkylidenecyclopropanes via Ru(II)-pheox catalyzed asymmetric inter- and intramolecular cyclopropanation of allenes
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An efficient protocol for the synthesis of optically active alkylidenecyclopropanes (ACPs) via the Ru(II)-Pheox catalyzed asymmetric cyclopropanation of allenes has been established. This catalytic system proceeded with high regioselectivity to give the A
- Chanthamath, Soda,Chua, Hao Wei,Kimura, Seiya,Shibatomi, Kazutaka,Iwasa, Seiji
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supporting information
p. 3408 - 3411
(2014/07/08)
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- Rhodium-catalyzed chemo-, regio-, and enantioselective addition of 2-pyridones to terminal allenes
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A rhodium-catalyzed chemo-, regio-, and enantio-selective addition of 2-pyridones to terminal allenes to give branched N-allyl 2-pyridones is reported. Preliminary mechanistic studies support the hypothesis that the reaction was initiated from the more acidic 2-hydroxypyridine form, and the initial kinetic O-allylation product was finally converted into the thermodynamically more stable N-allyl 2-pyridones.
- Li, Changkun,K?hny, Matthias,Breit, Bernhard
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supporting information
p. 13780 - 13784
(2015/02/05)
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- Highly selective copper-catalyzed hydroboration of allenes and 1,3-dienes
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The highly selective copper-catalyzed hydroboration of allenes has been developed. Allylboranes and alkenylboranes were selectively prepared by the judicious choice of catalytic species (copper hydride and boryl copper). Furthermore, two types of alkenylboranes could be selectively synthesized by the choice of an appropriate ligand. Mechanistic studies confirmed that the protonation of a (Z)-σ-allyl copper species, which was isolated and structurally characterized by single-crystal X-ray diffraction, was a key step in these reactions. Besides allenes, this method is also applicable to the selective hydroboration of 1,3-diene derivatives to afford allylboranes and homoallylboranes. Copyright
- Semba, Kazuhiko,Shinomiya, Masataka,Fujihara, Tetsuaki,Terao, Jun,Tsuji, Yasushi
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p. 7125 - 7132
(2013/07/04)
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- CuI-catalyzed synthesis of functionalized terminal allenes from 1-alkynes
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Relative to our original protocol that uses CuI (0.5 equiv.), paraformaldehyde (2.5 equiv.), and dicyclohexylamine (1.8 equiv.), a facile and efficient protocol for the gram-scale synthesis of functionalized terminal allenes by using CuI (7.5-10 mol-%), p
- Luo, Hongwen,Ma, Shengming
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p. 3041 - 3048
(2013/06/27)
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- Gold-catalyzed regioselective oxidation ofterminal allenes: Formation of α-methanesulfonyloxy methyl ketones
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Synthetically useful α-methanesulfonyloxy methyl ketones are readily prepared in one-step from terminal allenes in fair to good yields. The chemistry relies on a gold-catalyzed intermolecular oxidation of the 1,2-diene unit using 3,5-dichloropyridine N-ox
- Luo, Yingdong,Zhang, Guozhu,Hwang, Erik S.,Wilcoxon, Thomas A.,Zhang, Liming
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supporting information; experimental part
p. 596 - 600
(2011/06/26)
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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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- N-isopropylidene-N′-2-nitrobenzenesulfonyl hydrazine, a reagent for reduction of alcohols via the corresponding monoalkyl diazenes
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The reagent N-isopropylidene-N′-2-nitrobenzenesulfonyl hydrazine (IPNBSH) is used in the reduction of alcohols via the loss of dinitrogen from transiently formed monoalkyl diazene intermediates accessed by sequential Mitsunobu displacement, hydrolysis, and fragmentation under mild reaction conditions.
- Movassaghi, Mohammad,Ahmad, Omar K.
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p. 1838 - 1841
(2007/10/03)
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- Determination of the rate constant for ring opening of an a-cyclopropylvinyl radical
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The rate constant for ring opening of the l-(trans-2-phenylcyclopropyl)ethen-l-yl radical, 4, generated by photolysis of the corresponding vinyl iodide 2, is reported. The value of the rate constant was determined by the tin hydride method and was found t
- Milnes, Kaarina K.,Gottschling, Stephen E.,Baines, Kim M.
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p. 3530 - 3534
(2007/10/03)
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- Synthesis of allenes from allylic alcohol derivatives bearing a bromine atom using a palladium(0)/diethylzinc system
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A general and efficient synthesis of allenes using a palladium(0)/diethylzinc system is described. Treatment of mesylates or trichloroacetates of (E)- or (Z)-2-bromoalk-2-en-1-ols with diethylzinc in the presence of a catalytic amount of palladium(0) affords allenes bearing an aminoalkyl, alkyl, or aryl substituent(s) in good to high yields. No transfer of chirality from the stereogenic center carrying the mesyloxy group to the allene was observed.
- Ohno, Hiroaki,Miyamura, Kumiko,Tanaka, Tetsuaki,Oishi, Shinya,Toda, Ayako,Takemoto, Yoshiji,Fujii, Nobutaka,Ibuka, Toshiro
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p. 1359 - 1367
(2007/10/03)
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- A new method for synthesis of allenes, including an optically active form, from aldehydes and alkenyl aryl sulfoxides by sulfoxide-metal exchange as the key reaction and an application to a total synthesis of male bean weevil sex attractant
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The sulfoxide-metal exchange reaction of β-acetoxy sulfoxides or β-mesyloxy sulfoxides, which were derived from alkenyl aryl sulfoxides and aldehydes in two steps, with a Grignard reagent or alkyllithium at low temperature gave allenes in good yields. Optically active allenes were synthesized starting from optically active 2-substituted ethenyl p-tolyl sulfoxides. A synthesis of (-)-methyl (E)-2,4,5-tetradecatrienoate, a male bean weevil sex attractant, was realized by this method.
- Satoh, Tsuyoshi,Hanaki, Noriko,Kuramochi, Yuko,Inoue, Yujiro,Hosoya, Kayo,Sakai, Ken
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p. 2533 - 2549
(2007/10/03)
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- Allenes through Horner-Wadsworth-Emmons olefination of alkenylphosphonates
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Mono- and di-substituted allenes 5 were synthesized by successive Horner-Wadsworth-Emmons olefination starting from methylene-bisphosphonate 1 and two carbonyl compounds. The key to success is KH or KH-18-crown-6 as a base for the second HWE olefination o
- Nagaoka, Yasuo,Inoue, Hideki,Tomioka, Kiyoshi
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p. 1843 - 1846
(2007/10/03)
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- Magnesium cyclopropylidenes generated from 1-chlorocyclopropyl phenyl sulfoxides with Grignard reagents: Their properties, and a sulfoxide version of the Doering-Moore-Skattebol reaction
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Magnesium cyclopropylidenes were generated from 1-chlorocyclopropyl phenyl sulfoxides with Grignard reagents (EtMgCl or i-PrMgCl) in THF at -78°C in high yields by a sulfoxide-magnesium exchange reaction. The generated magnesium cyclopropylidenes were found to be stable at below -60°C for at least 3 h. It was also found that the pyramidal inversion of the magnesium carbenoid was quite slow at below -60°C. When the sulfoxide-magnesium exchange reaction was conducted with phenylmagnesium chloride at 0°C, the 1-chlorocyclopropyl phenyl sulfoxides gave allenes in good to high yields.
- Satoh,Kurihara,Fujita
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p. 5369 - 5375
(2007/10/03)
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- General method for preparation of allenic zinc reagents by three-carbon homologation of triorganozincates: Convergent three-component coupling of propargylic substrates, triorganozincates, and electrophilic reagents
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Allenic zinc reagents (R1R2C=C=C(R3)ZnL) are efficiently prepared by the reaction of propargylic substrates (R1R2C(X)C≡CH, X = MeSO2O,Cl, R2NCO2) with a variety of tri
- Harada, Toshiro,Katsuhira, Takeshi,Osada, Atsushi,Iwazaki, Katsuhiro,Maejima, Keiji,Oku, Akira
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p. 11377 - 11390
(2007/10/03)
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- Chemistry of gem-Dihalocyclopropanes. XXII. Intramolecular Addition of Cyclopropylidenes to Aliphatic and Aromatic Double Bonds. A Synthesis of 2-Alkenyltropones
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Substituted gem-dibromocyclopropanes containing a vinylic or phenolic ether oxygen α to the cyclopropane ring undergo intramolecular cycloaddition as well as ring opening to allenes when treated with methyllithium.Cycloaddition of derivatives with a vinyl
- Skatteboel, Lars,Nilsen, Nils O.,Myhren, Finn
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p. 782 - 790
(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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- A CONVENIENT SYNTHESIS OF ALLENES BY THE REACTION OF PROPARGYL ALCOHOLS WITH GRIGNARD REAGENTS USING 1-CHLORO-2-METHYL-N,N-TETRAMETHYLENEPROPENYLAMINE
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1-Chloro-2-methyl-N,N-tetramethylenepropenylamine was found to be an efficient condensation reagent for the regioselective coupling reaction of propargyl alcohols with Grignard reagents to give allenes in good yields with high chemo- and enantioselectivities.The utility of the reaction was demonstrated in the stereocontrolled synthesis of methyl (E)-2,4,5-tetradecatrienoate, the pheromone of the male dried bean beetle.
- Fujisawa, Tamotsu,Iida, Sachio,Sato, Toshio
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p. 4007 - 4010
(2007/10/02)
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