- Poly(ethylene glycol) Promoted Reactions of Vinylic Dibromides. Dehydrohalogenation and Palladium(0)-Catalyzed Formal Oxidative Homologation
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Aldehydes are converted to the homologous acids by a simple two-step procedure involving initial generation of a vinylic dibromide followed by Pd(diphos)2 catalyzed, poly(ethylene glycol) induced reaction with base.This reaction is useful for aromatic and α,β-unsaturated aldehydes and is also applicable to cyclic as well as alkyl aryl ketones. 1-Bromoalkynes are formed in good yields when the vinylic dibromide reaction is effected in the absence of the palladium(0) catalyst.
- Li, Pei,Alper, Howard
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- Visible-Light-Promoted Oxo-Sulfonylation of Ynamides with Sulfonic Acids
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A visible-light-promoted oxo-sulfonylation of ynamides with sulfonic acids is reported, giving rise to a collection of functionalized α-sulfonylated amides in a straightforward manner. The reaction proceeds sequentially through a cascade of electrophilic addition and photoinduced sulfonyl radical-sustained skeleton rearrangement. The high atom economy, mild reaction conditions, and wide substrate scope comprised the merits of this synthetic transformation.
- Wang, Lu,Lu, Chengrong,Yue, Yanni,Feng, Chao
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supporting information
p. 3514 - 3517
(2019/05/16)
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- Nickel-Catalyzed Reductive 1,2-Dialkynylation of Alkenes Bearing an 8-Aminoquinoline Directing Group
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An unprecedented nickel-catalyzed reductive 1,2-dialkynylation of alkenes bearing an 8-aminoquinoline directing group has been developed. This method proceeded through a migratory insertion/reductive-coupling process under mild conditions with a wide substrate scope and good functional group tolerance, providing direct access to the synthetically flexible 1,5-diynes. Moreover, the 1,2-dialkynylation products could be further converted to borate-ester- or azide-functionalized 1,5-dienes, ditriazole, β-diyne primary amide, and trisubstituted benzene.
- Pan, Rui,Shi, Cong,Zhang, Dongquan,Tian, Yang,Guo, Songjin,Yao, Hequan,Lin, Aijun
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supporting information
p. 8915 - 8920
(2019/11/14)
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- Palladium-Catalyzed Oxygenative Cross-Coupling of Ynamides and Benzyl Bromides by Carbene Migratory Insertion
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A palladium-catalyzed oxygenative cross-coupling of ynamides and benzyl bromides has been developed. After subsequent hydrogenation, α,α-disubstituted amide derivatives were obtained in good yields. Migratory insertion of α-oxo palladium carbene species, generated by intermolecular oxidation, is proposed as the key step in this reaction. The study demonstrates the potential of ynamides to serve as carbene precursors in palladium-catalyzed C?C bond-forming cross-coupling reactions.
- Gao, Yunpeng,Wu, Guojiao,Zhou, Qi,Wang, Jianbo
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supporting information
p. 2716 - 2720
(2018/02/13)
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- Gold-Catalyzed Intermolecular [4+2] Annulation of 2-Ethynylanilines with Ynamides: An Access to Substituted 2-Aminoquinolines
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A gold-catalyzed intermolecular [4+2] annulation of easily accessible 2-ethynylanilines with ynamides offers a highly region-selective, modular, efficient, and atom-economical strategy for the synthesis of substituted 2-aminoquinolines in up to 93% yield. (Figure presented.).
- Zhao, Ximei,Song, Xinlong,Jin, Hongming,Zeng, Zhongyi,Wang, Qian,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 2720 - 2726
(2018/07/29)
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- Cyclobutene vs 1,3-Diene Formation in the Gold-Catalyzed Reaction of Alkynes with Alkenes: The Complete Mechanistic Picture
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The intermolecular gold(I)-catalyzed reaction between arylalkynes and alkenes leads to cyclobutenes by a [2 + 2] cycloaddition, which takes place stepwise, first by formation of cyclopropyl gold(I) carbenes, followed by a ring expansion. However, 1,3-butadienes are also formed in the case of ortho-substituted arylalkynes by a metathesis-type process. The corresponding reaction of alkenes with aryl-1,3-butadiynes, ethynylogous to arylalkynes, leads exclusively to cyclobutenes. A comprehensive mechanism for the gold(I)-catalyzed reaction of alkynes with alkenes is proposed on the basis of density functional theory calculations, which shows that the two pathways leading to cyclobutenes or dienes are very close in energy. The key intermediates are cyclopropyl gold(I) carbenes, which have been independently generated by retro-Buchner reaction from stereodefined 1a,7b-dihydro-1H-cyclopropa[a]naphthalenes.
- De Orbe, M. Elena,Amenós, Laura,Kirillova, Mariia S.,Wang, Yahui,López-Carrillo, Verónica,Maseras, Feliu,Echavarren, Antonio M.
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supporting information
p. 10302 - 10311
(2017/08/09)
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- Borane-catalyzed selective hydrosilylation of internal ynamides leading to β-silyl (Z)-enamides
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We have developed a borane-catalyzed regioand stereoselective hydrosilylation of internal ynamides for the first time. The scope of ynamide substrates and silane reactants was broad under mild reaction conditions, affording synthetically versatile β-silyl (Z)-enamide products. The observed stereoselectivity was reasoned to be due to the β-silicon effect on a postulated ketene iminium intermediate.
- Kim, Youngchan,Dateer, Ramesh B.,Chang, Sukbok
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supporting information
p. 190 - 193
(2017/11/27)
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- Controlled Reactivity of 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) in the Selective Synthesis of 1-(Bromoethynyl)arenes
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The nucleophilic reactivity of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) was completely controlled by the formation of monohydrate (DBU?H2O) in the synthesis of 1-(bromoethynyl)arenes from 1,1-dibromoalkenes. Differential reactivity of DBU in pr
- Krishna Moodapelly, Shiva,Sharma, Gangavaram V. M.,Ramana Doddi, Venkata
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supporting information
p. 1535 - 1540
(2017/05/05)
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- Gold-Catalyzed Intermolecular Nitrene Transfer from 2H-Azirines to Ynamides: A Direct Approach to Polysubstituted Pyrroles
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(Chemical Equation Presented). An effective gold-catalyzed intermolecular nitrene transfer by the reaction of 2H-azirines and ynamides is reported, which provides highly substituted pyrroles in a straightforward manner. This transformation proceeds under mild conditions and gives the polysubstituted pyrroles in good-to-excellent yields. Preliminary results indicate that a nongold carbenoid pathway is preferred for current pyrrole synthesis.
- Zhu, Lei,Yu, Yinghua,Mao, Zhifeng,Huang, Xueliang
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supporting information
p. 30 - 33
(2015/07/28)
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- Copper-catalyzed N-alkynylations of sulfoximines with bromoacetylenes
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N-Alkynylated sulfoximines have been obtained by copper-catalyzed cross-coupling reactions starting from NH-sulfoximines and bromoacetylenes in moderate to good yields. The reaction conditions are mild, and the substrate scope is wide.
- Chen, Xiao Yun,Wang, Long,Frings, Marcus,Bolm, Carsten
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supporting information
p. 3796 - 3799
(2014/08/05)
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- Intramolecular carbocupration of N-aryl-ynamides: A modular indole synthesis
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A modular indole synthesis based on an intramolecular 5-endo-dig carbocupration starting from readily available N-aryl-ynamides is reported. A variety of ynamides are converted to indoles in moderate to good yields and with varying substitution pattern on the indole ring. This further extends the synthetic utility of ynamides in organic synthesis and provides additional insights on the use of intramolecular carbometalation reactions.
- Gati, Wafa,Couty, Francois,Boubaker, Taoufik,Rammah, Mohamed M.,Rammah, Mohamed B.,Evano, Gwilherm
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supporting information
p. 3122 - 3125
(2013/07/26)
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- Catalytic electrophilic halogenation of silyl-protected and terminal alkynes: Trapping gold(I) acetylides vs. a Bronsted acid-promoted reaction
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In the presence of a cationic gold(I) catalyst and N-halosuccinimide, both trimethylsilyl-protected and terminal alkynes are converted into alkynyl halides. Further experiments showed that silyl-protected alkynes undergo electrophilic iodination and bromination under Bronsted acid catalysis, whilst terminal alkynes require a cationic gold catalyst. The former reactions probably proceed via activation of the electrophile, whilst the latter reactions proceed via a gold(I) acetylide intermediate. Gold-catalysed halogenation was further combined with gold-catalysed hydration and subsequent annulation to provide convenient routes to iodomethyl ketones and five-membered aromatic heterocycles. Copyright
- Starkov, Pavel,Rota, Filippo,D'Oyley, Jarryl M.,Sheppard, Tom D.
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supporting information
p. 3217 - 3224
(2013/01/15)
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- Palladium-catalyzed bromoalkynylation of C-C double bonds: Ring-structure-dependent synthesis of 7-alkynyl norbornanes and cyclobutenyl halides
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Strain versus flexibility: The palladium-catalyzed reaction of haloalkynes with norbornene derivatives leads to 7-alkynyl norbornane products (see scheme). Key to the success of this reaction is the formation of a "bridging" palladium species, which can rearrange to result in a C-7 functionalization. The ring-structure-dependent [2+2] cycloaddition of haloalkynes with cyclooctene has been achieved in moderate to good yields under similar conditions. Copyright
- Li, Yibiao,Liu, Xiaohang,Jiang, Huanfeng,Liu, Bifu,Chen, Zhengwang,Zhou, Peng
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supporting information; experimental part
p. 6341 - 6345
(2011/09/13)
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- Alkynyl halides in ruthenium(II)-catalyzed [2+2] cycloadditions of bicyclic alkenes
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Ru-catalyzed [2+2] cycloadditions between bicyclic alkenes and alkynyl halides were found to occur in moderate to good yields. The presence of the halide moiety greatly enhances the reactivity of the alkyne component in the cycloaddition and can be transformed into a variety of products that are difficult or impossible to obtain by direct cycloaddition. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Allen, Anna,Villeneuve, Karine,Cockburn, Neil,Fatila, Elisabeth,Riddell, Nicole,Tam, William
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experimental part
p. 4178 - 4192
(2009/05/27)
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- Ruthenium-catalyzed [2 + 2] cycloadditions between bicyclic alkenes and alkynyl halides
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(Chemical equation presented) Ru-catalyzed [2 + 2] cycloadditions between norbornadiene and alkynyl halides were found to occur in moderate to good yields (32-89%). The presence of the halide moiety greatly enhances the reactivity of the alkyne component in the cycloaddition and can be transformed into a variety of products that are difficult or impossible to obtain via direct cycloaddition.
- Villeneuve, Karine,Riddell, Nicole,Jordan, Robert W.,Tsui, Gavin C.,Tam, William
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p. 4543 - 4546
(2007/10/03)
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