- Crossed beam reaction of phenyl radicals with unsaturated hydrocarbon molecules. I. Chemical dynamics of phenylmethylacetylene (C6H5CCCH3;X1A') formation from reaction of C6H5(X2A1) with methylacetylene, CH3CCH(X1A1)
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The chemical reaction dynamics to form phenylmethylacetylene, C6H5CCCH3(X2A'), via reactive collisions of the phenyl radical C6H5(X2A1) with methylacetylene, CH3CCH(X1A1), are unraveled under single collision conditions in a crossed molecular beam experiment at a collision energy of 140 kJ mol-1. The laboratory angular distribution and time-of-flight spectra of C9H8+ at m/e = 116 indicate the existence of a phenyl radical versus hydrogen replacement pathway. Partially deuterated methylacetylene, CH3CCD(X1A1), was used to identify the site of the carbon-hydrogen bond cleavage. Only the loss of the acetylenic hydrogen atom was observed; the methyl group is conserved in the reaction. Electronic structure calculations reveal that the reaction has an entrance barrier of about 17 KJ mol-1. Forward-convolution fitting of our data shows that the chemical reaction dynamics are on the boundary between an osculating complex and a direct reaction and are governed by an initial attack of the C6H5 radical to the π electron density of the Cl carbon atom of the methylacetylene molecule to form a short lived, highly rovibrationally excited (C6H5)HCCCH3 intermediate. The latter loses a hydrogen atom to form the phenylmethylacetylene molecule on the 2A' surface. The phenylallene isomer channel was not observed experimentally. The dynamics of the title reaction and the identification of the phenyl versus hydrogen exchange have a profound impact on combustion chemistry and chemical processes in outflows of carbon stars. For the first time, the reaction of phenyl radicals with acetylene and/or substituted acetylene is inferred experimentally as a feasible, possibly elementary reaction in the stepwise growth of polycyclic aromatic hydrocarbon precursor molecules and alkyl substituted species in high temperature environments such as photospheres of carbon stars and oxygen poor combustion systems.
- Kaiser,Asvany,Lee,Bettinger,Schleyer,Schaefer III
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- An Experimental and Computational Investigation of (α-Methylbenzylidene)carbene
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Photolysis of 1-(1-phenylethylidene)-1a,9b-dihydro-1H-cyclopropa[l]phenanthrene, in C6H6 (or C6D6), at ambient temperature, produces (α-methylbenzylidene)carbene which undergoes a facile Fritsch-Buttenberg-Wiechell (FBW)-type rearrangement to 1-phenylpropyne. The alkyne results exclusively from a 1,2-phenyl shift as evident from the use of a 13C-labeled precursor. This experimental result is consistent with CCSD(T)/cc-pVTZ//B3LYP/6-31+G? calculations which reveal that a 1,2-phenyl shift in the singlet carbene needs to overcome a barrier of only 3.8 kcal/mol whereas the 1,2-methyl shift has to surmount a much larger barrier of 11.9 kcal/mol. The alkyne remains the predominant product when the photolysis is carried out in cyclohexene but the carbene-alkene cycloadduct could be detected, albeit in low yield, in the photolysate.
- Yang, Xi,Languet, Keith,Thamattoor, Dasan M.
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- Rh(iii)-Catalyzed olefination to build diverse oxazole derivatives from functional alkynes
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A novel Rh(iii)-catalyzed olefination reaction of oxazoles to generate diverse oxazole skeleton derivatives has been realized by directly using oxazole as the directing group. The reaction could tolerate many functional groups, affording complex oxazole derivatives with long chain alkenyls in moderate to good yields, which might find applications in the construction of diverse compounds.
- He, Yuan,Zheng, Ting,Huang, Yin-Hui,Dong, Lin
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supporting information
p. 4937 - 4942
(2021/06/16)
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- Regio- And stereoselective electrochemical synthesis of sulfonylated enethers from alkynes and sulfonyl hydrazides
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An electrooxidative direct difunctionalization of internal alkynes with sulfonyl hydrazides has been developed for the construction of sulfonated enethers. In this transformation, metal catalysts or stoichiometric amount of oxidants are not required and molecular nitrogen and hydrogen are the sole byproducts, providing a simple and green approach for preparing various sulfonyl tetrasubstituted alkenes. Notably, the protocol could be efficiently scaled up and the follow-up procedures of the corresponding functionalized alkenes demonstrate the practicality of the electrochemical synthesis.
- Du, Wu-Bo,Wang, Ning-Ning,Pan, Chao,Ni, Shao-Fei,Wen, Li-Rong,Li, Ming,Zhang, Lin-Bao
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supporting information
p. 2420 - 2426
(2021/04/07)
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- Regio- and Diastereoselective Copper-Catalyzed Carbomagnesiation for the Synthesis of Penta- and Hexa-Substituted Cyclopropanes
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Despite the highly strained nature of cyclopropanes possessing three vicinal quaternary carbon stereocenters, the regio- and diastereoselective copper-catalyzed carbomagnesiation reaction of cyclopropenes provides an easy and efficient access to these novel persubstituted cyclopropyl cores with a complete regio- and diastereoselectivity.
- Cohen, Yair,Augustin, André U.,Levy, Laura,Jones, Peter G.,Werz, Daniel B.,Marek, Ilan
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supporting information
p. 11804 - 11808
(2021/04/26)
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- Iron-Catalyzed Contrasteric Functionalization of Allenic C(sp2)-H Bonds: Synthesis of α-Aminoalkyl 1,1-Disubstituted Allenes
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An iron-catalyzed C-H functionalization of simple monosubstituted allenes is reported. An efficient protocol for this process was made possible by the use of a newly developed electron-rich and sterically hindered cationic cyclopentadienyliron dicarbonyl complex as the catalyst andN-sulfonyl hemiaminal ether reagents as precursors to iminium ion electrophiles. Under optimized conditions, the use of a mild, functional-group-tolerant base enabled the conversion of a range of monoalkyl allenes to their allenylic sulfonamido 1,1-disubstituted derivatives, a previously unreported and contrasteric regiochemical outcome for the C-H functionalization of electronically unbiased and directing-group-free allenes.
- Durham, Austin C.,Murphy, Ethan,Palermo, Philip N.,Scrivener, Sarah G.,Wang, Ruihan,Wang, Yi-Ming,Wang, Yidong,Zuo, Xiao-Dong
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supporting information
p. 14998 - 15004
(2021/09/30)
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- Fritsch-Buttenberg-Wiechell rearrangement of magnesium alkylidene carbenoids leading to the formation of alkynes
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A series of 1-heteroatom-substituted vinyl p-tolyl sulfoxides were prepared and treated with organometallic reagents to evaluate which combination of sulfoxides and organometallic reagents yielded alkynes the most efficiently. The use of 1-chlorovinyl p-tolyl sulfoxide and isopropylmagnesium chloride was optimal for this purpose. A variety of 1-chlorovinyl p-tolyl sulfoxides were prepared from carbonyl compounds and chloromethyl p-tolyl sulfoxide and were converted into alkynes via the sulfoxide/magnesium exchange reaction and subsequent Fritsch-Buttenberg-Wiechell (FBW) rearrangement of the resulting magnesium alkylidene carbenoids. The mechanism of the FBW rearrangement of magnesium alkylidene carbenoids was studied by using13C-labeled sulfoxides and by using DFT calculations.
- Ando, Akane,Imafuji, Aki,Kimura, Tsutomu,Sekiguchi, Koto
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p. 1352 - 1359
(2021/06/06)
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- Xantphos-coordinated palladium dithiolates: Highly efficient catalyst for decarboxylative Sonogashira reaction into corresponding alkynes
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This work reports Xantphos-coordinated palladium dithiolate complexes as catalysts for decarboxylative Sonogashira coupling reaction of phenyl propiolic acid and 2-butynoic acid with various iodoarenes. These palladium aryl dithiolate complexes were synthesized and characterized by 1H and 31P nuclear magnetic resonance (NMR) spectroscopy, melting point, and elemental analysis (CHNS). Synthetic utility for the reported protocol is explored for the effect of various functional groups on the yield of corresponding heteroaryl alkynes. The current protocol showed excellent catalytic activity towards decarboxylative alkynylation reaction with high turn-over number (TON) up to 105 and turn-over frequency (TOF) up to 104 h?1. The catalyst could be recycled up to six recycles without losing its catalytic activity. The in situ generation of palladium nanoparticles (PdNPs) was observed after the third recycle, and the amount was significant after the sixth recycle, which were confirmed and characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive X-ray (EDX) analysis and high-resolution transmission electron microscopy (HR-TEM). The catalytic activity of the reaction is attributed to the formation of PdNPs.
- Lokolkar, Manjunath S.,Mane, Pravin A.,Dey, Sandip,Bhanage, Bhalchandra M.
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- Rh-Catalyzed Asymmetric Hydrogenation of α,β- and β,β-Disubstituted Unsaturated Boronate Esters
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A highly enantioselective hydrogenation of α,β-unsaturated boronate esters catalyzed by Rh-(S)-DTBM-Segphos complex has been developed. Both (Z)-α,β- and β,β-disubstituted substrates can be successfully hydrogenated to afford chiral boronates with excellent enantioselectivities, up to 98 % ee. Furthermore, the obtained chiral boronate esters, as important versatile synthetic intermediates are successfully transformed to the corresponding chiral alcohols, amines and other important derivatives with maintained enantioselectivities.
- Hou, Guohua,Shen, Xin,Yan, Qiaozhi,Zi, Guofu
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supporting information
(2020/05/08)
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- Sodium-metal-promoted reductive 1,2-syn-diboration of alkynes with reduction-resistant trimethoxyborane
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Reductive 1,2-diboration of alkynes has been accomplished by means of sodium dispersion in the presence of trimethoxyborane as a reduction-resistant boron electrophile. Two boron moieties can be introduced onto alkynes with excellent syn selectivity to afford the corresponding (Z)-1,2-diborylalkenes. Bis(borate) species generated in situ can be involved in one-pot Suzuki-Miyaura arylation, formal arylboration of alkynes thus being executed.
- Fukazawa, Mizuki,Ito, Shiori,Nogi, Keisuke,Takahashi, Fumiya,Yorimitsu, Hideki
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p. 1171 - 1179
(2020/10/18)
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- Insertion of Alkylidene Carbenes into B-H Bonds
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We have developed a protocol for insertion of alkylidene carbenes into the B-H bonds of amine-borane adducts, enabling, for the first time, the construction of C(sp2)-B bonds by means of carbene-insertion reactions. Various acyclic and cyclic alkenyl borane-amine adducts were prepared from readily accessible starting materials in good to high yields and were subsequently subjected to a diverse array of functional group transformations. The unprecedented spiro B-N heterocycles prepared in this study have potential utility as building blocks for the synthesis of pharmaceuticals. Preliminary mechanistic studies suggest that insertion of the alkylidene carbenes into the B-H bonds of the amine-borane adducts proceeds via a concerted process involving a three-membered-ring transition state.
- Yang, Ji-Min,Guo, Feng-Kai,Zhao, Yu-Tao,Zhang, Qiao,Huang, Ming-Yao,Li, Mao-Lin,Zhu, Shou-Fei,Zhou, Qi-Lin
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supporting information
p. 20924 - 20929
(2020/12/23)
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- Synthesis of trisubstituted alkenes by Ni-catalyzed hydroalkylation of internal alkynes with cycloketone oxime esters
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A method for Ni-catalyzed hydroalkylation of internal alkynes with cycloketone oxime esters was developed. The reaction has a broad substrate scope. This hydroalkylation shows excellent regio-and stereo-selectivity. This method enables readily available starting materials to be used to access a range of cyano-substituted single-configuration trisubstituted alkenes. These are valuable feedstock chemicals and are widely used in synthetic and medicinal chemistry.
- Lu, Xiao-Yu,Liu, Chuang-Chuang,Jiang, Run-Chuang,Yan, Lu-Yu,Liu, Qi-Le,Wang, Qing-Qing,Li, Jia-Mei
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supporting information
p. 14191 - 14194
(2020/11/24)
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- Direct Synthesis of Propen-2-yl Sulfones through Cascade Reactions Using Calcium Carbide as an Alkyne Source
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A simple method for the construction of propen-2-yl sulfones through cascade reactions of calcium carbide with arylsulfonylhydrazones using copper as a mediator is described. The salient features of this protocol are the use of readily available and easy-to-handle alkyne source, broad substrate scope, open-air condition, and simple operation procedure.
- Gao, Lei,Liu, Zhenrong,Ma, Xiaolong,Li, Zheng
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supporting information
p. 5246 - 5250
(2020/07/04)
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- Palladium-catalyzed methylation of terminal alkynes
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In this communication, a palladium-catalyzed procedure for the methylation of terminal alkynes has been developed. With N,N,N-trimethylbenzenaminium trifluoromethanesulfonate as the methyl source, various desired products were obtained in moderate to good yields. Both aromatic and aliphatic alkynes are applicable.
- Wang, Wei-Feng,Wu, Xiao-Feng
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- The ruthenium(ii)-catalyzed C-H olefination of indoles with alkynes: The facile construction of tetrasubstituted alkenes under aqueous conditions
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An environmentally-friendly and facile protocol for the construction of tetrasubstituted alkenes has been established with Ru(ii)-catalyzed C-H bond functionalizations under mild conditions. The method features the usage of readily available substrates, without external oxidants and additives, 100% atom economy, and excellent regioselectivity, thus enhancing the practicability of this protocol. Moreover, this transformation proceeded smoothly under aqueous conditions and could be extended to the gram scale. N-Methoxyamide, as a directing group (DG), played a vital role in the transformation.
- Li, Ming,Yao, Tian-Yu,Sun, Sheng-Zheng,Yan, Ting-Xun,Wen, Li-Rong,Zhang, Lin-Bao
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supporting information
p. 3158 - 3163
(2020/05/08)
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- A novel approach for rhodium(iii)-catalyzed C-H functionalization of 2,2′-bipyridine derivatives with alkynes: A significant substituent effect
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We described a novel approach for the C-H functionalization of 2,2′-bipyridine derivatives with alkynes. DFT calculations and experimental data showed a significant substituent effect at the 6-position of 2,2′-bipyridine, which weakened the adjacent N-Rh bond and provided the possibility of subsequent rollover cyclometalation, C-H activation, and functionalization.
- Wu, Shaonan,Wang, Zhuo,Bao, Yinwei,Chen, Chen,Liu, Kun,Zhu, Bolin
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supporting information
p. 4408 - 4411
(2020/05/05)
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- Direct Synthesis of 1-Arylprop-1-ynes with Calcium Carbide as an Acetylene Source
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A simple method is described for the synthesis of 1-arylprop-1-ynes directly from aromatic aldehyde p -tosylhydrazones by using calcium carbide as an acetylene source. The salient features of this protocol are its use of a readily available and easily handled source of acetylene, its operational simplicity, its high yield, and its broad substrate scope.
- Gao, Lei,Li, Zheng
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supporting information
p. 1580 - 1584
(2019/08/20)
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- Migratory Aptitudes in Rearrangements of Destabilized Vinyl Cations
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The Lewis acid-promoted generation of destabilized vinyl cations from β-hydroxy diazo ketones leads to an energetically favorable 1,2-shift across the alkene followed by an irreversible C-H insertion to give cyclopentenone products. This reaction sequence overcomes typical challenges of counter-ion trapping and rearrangement reversibility of vinyl cations and has been used to study the migratory aptitudes of nonequivalent substituents in an uncommon C(sp2) to C(sp) vinyl cation rearrangement. The migratory aptitude trends were consistent with those observed in other cationic rearrangements; the substituent that can best stabilize a cation more readily migrates. However, density functional theory calculations show that the situation is more complex. Selectivity in the formation of one conformational isomer of the vinyl cation and facial selective migration across the alkene due to an electrostatic interaction between the vinyl cation and the adjacent carbonyl oxygen work in concert to determine which group migrates. This study provides valuable insight into predicting migration preferences when applying this methodology to the synthesis of structurally complex cyclopentenones that are differentially substituted at the α and β positions.
- Brewer, Matthias,Cleary, Sarah E.,Hensinger, Magenta J.,Hong, Xin,Qin, Zhi-Xin
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p. 15154 - 15164
(2019/11/28)
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- Iron-Catalyzed Cross-Coupling of Alkynyl and Styrenyl Chlorides with Alkyl Grignard Reagents in Batch and Flow
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Transition-metal-catalyzed cross-coupling chemistry can be regarded as one of the most powerful protocols to construct carbon–carbon bonds. While the field is still dominated by palladium catalysis, there is an increasing interest to develop protocols that utilize cheaper and more sustainable metal sources. Herein, we report a selective, practical, and fast iron-based cross-coupling reaction that enables the formation of Csp?Csp3 and Csp2?Csp3 bonds. In a telescoped flow process, the reaction can be combined with the Grignard reagent synthesis. Moreover, flow allows the use of a supporting ligand to be avoided without eroding the reaction selectivity.
- Deng, Yuchao,Wei, Xiao-Jing,Wang, Xiao,Sun, Yuhan,No?l, Timothy
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p. 14532 - 14535
(2019/11/21)
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- Reactivity of [TismPriBenz]MgMe towards secondary amines and terminal alkynes: Catalytic dehydrocoupling with hydrosilanes to afford Si–N and Si–C bonds
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The magnesium hydride and methyl compounds, [TismPriBenz]MgX (X = H, Me), react with diphenylamine (Ph2NH)and pyrrolidine (C4H8NH)to afford the amide derivatives, [TismPriBenz]MgNPh2 and [TismPriBenz]MgNC4H8, while reactions with the terminal alkynes, PhC[tbnd]CH and BunC[tbnd]CH, afford the corresponding acetylide derivatives, [TismPriBenz]MgC[tbnd]CPh and [TismPriBenz]MgC[tbnd]CBun. The Mg[sbnd]N bond of [TismPriBenz]MgNR2 may be cleaved by hydrosilanes, such that [TismPriBenz]MgMe is an effective precatalyst for the dehydrocoupling of hydrosilanes and amines. For example, [TismPriBenz]MgMe enables the conversion of a 1:1 mixture of Ph2SiH2 and C4H8NH at room temperature to the silazane, Ph2SiH(NC4H8). [TismPriBenz]MgH and [TismPriBenz]MgMe are also capable of dehydrocoupling PhC[tbnd]CH and PhSiH3 to form PhSiH2C[tbnd]CPh. In addition to dehydrocoupling of terminal alkynes, [TismPriBenz]MgMe is also capable of achieving the isomerization 3-phenyl-1-propyne to phenylallene.
- Rauch, Michael,Roberts, Renee C.,Parkin, Gerard
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p. 271 - 279
(2019/07/02)
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- Unusual Formation of Cyclopenta[ b]indoles from 3-Indolylmethanols and Alkynes
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Acid-promoted synthesis of cyclopenta[b]indole frameworks from 3-indolylmethanols and alkynes has been reported. The overall transformation represents a formal [3 + 2] annulation via rearrangement. This protocol showed good generality for the carbinol substrates as well as alkynes and allowed the generation of structurally diverse cyclopenta[b]indoles. Terminal alkynes, dialkyl-substituted internal alkynes, and alkynes with electron-deficient substituents were found to be not suitable for this transformation. Similarly, N-Ts and N-Boc groups were compatible with reaction conditions, whereas N-Ac and N-Tf failed to undergo this reaction. Isolation of vinyl chloride intermediate suggested the involvement of a vinylic carbocation intermediate. A mechanism has been proposed involving a ring-opening-ring-closing cascade followed by a 1,3-indole migration process via a spirocyclobutene intermediate.
- Gandhi, Soniya,Baire, Beeraiah
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p. 3904 - 3918
(2019/04/25)
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- Facile Access to Diverse Libraries of Internal Alkynes via Sequential Iododediazoniation/Decarboxylative Sonogashira Reaction in Imidazolium ILs without Ligand or Additive
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Convenient access to diverse libraries of internal alkynes via decarboxylative Sonogashira reaction of alkynyl-carboxylic acids with iodoarenes, employing imidazolium-ILs as solvent, along with piperidine-appended imidazolium [PAIM][NTf2] as task-specific basic IL is demonstrated, without the need for any ligand or additive. The feasibility to perform these reactions by sequential one-pot iododediazoniation/decarboxylative Sonogashira reaction is also shown, and the scope of the methods is underscored by providing 29 examples. The potential for recycling and reuse of the IL solvent is also examined.
- Prabhala, Pavankumar,Savanur, Hemantkumar M.,Kalkhambkar, Rajesh G.,Laali, Kenneth K.
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p. 2061 - 2064
(2019/03/07)
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- Rhodium(iii)-catalyzed unreactive C(sp3)-H alkenylation of N-alkyl-1H-pyrazoles with alkynes
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The first example of pyrazole-directed rhodium(iii)-catalyzed unreactive C(sp3)-H alkenylation with alkynes has been described, which showed a relatively broad substrate scope with good functional group compatibility. Moreover, we demonstrated that the transitive coordinating center pyrazole could be easily removed under mild conditions.
- Li, Tongyu,Liu, Chang,Wu, Shaonan,Chen, Chen C.,Zhu, Bolin
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supporting information
p. 7679 - 7683
(2019/08/30)
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- Gold-Catalyzed Hydrohydrazidation of Terminal Alkynes
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Facile gold-catalyzed hydrohydrazidation of alkynes with various hydrazides R2CONHNH2 (R = Alk or Ar; including those with an additional nucleophilic moiety) in the presence of Ph3PAuNTf2 (6 mol %) leading to a wide range of substituted keto-N-acylhydrazones (18 examples) in excellent to good yields (99-66%) is reported. This novel metal-catalyzed coupling proceeds under mild conditions (chlorobenzene, 60 °C), exhibits high functional group tolerance, and is insensitive to the electronic and steric effects of the substituents in the reactants.
- Zimin, Dmitry P.,Dar'In, Dmitry V.,Rassadin, Valentin A.,Kukushkin, Vadim Yu.
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supporting information
p. 4880 - 4884
(2018/08/24)
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- Direct Enantioselective α-Allylation of Unfunctionalized Cyclic Ketones with Alkynes through Pd-Amine Cooperative Catalysis
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The first direct enantioselective α-allylation of unfunctionalized cyclic ketones using alkynes as an economical choice of reagent is reported. This transformation uses a simple procedure with commercially available palladium, chiral bisphosphine ligand and chiral amine catalysts, and affords valuable ketones with a α-tertiary stereocenter in good to high enantiopurity. In this transformation, a chiral palladium complex containing the (S)-DIFLUORPHOS ligand catalyzes the isomerization of alkynes into an electrophilic allylpalladium species, which is attacked by the enamine generated in situ from the condensation of (R)-prolinol with the ketone substrate.
- Lee, Jin Tu Danence,Zhao, Yu
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supporting information
p. 9520 - 9524
(2018/06/04)
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- Copper-NHC-Mediated Semihydrogenation and Hydroboration of Alkynes: Enhanced Catalytic Activity Using Ring-Expanded Carbenes
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A series of two-coordinate copper tert-butoxide complexes bearing five-, six-, and seven-membered ring N-heterocyclic carbenes, prepared by protonolysis of (NHC)CuMes with tBuOH, have been used as catalytic precursors in the semihydrogenation of alkynes with silanes/tBuOH and the hydroboration of alkynes with HBPin. Both processes proceed with high regioselectivity and show enhancements with six- and seven-membered ring carbenes.
- Hall, Jonathan W.,Unson, Darcy M. L.,Brunel, Paul,Collins, Lee R.,Cybulski, Mateusz K.,Mahon, Mary F.,Whittlesey, Michael K.
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supporting information
p. 3102 - 3110
(2018/09/12)
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- Propargylic C(sp3)-H Bond Activation for Preparing η3-Propargyl/Allenyl Complexes of Yttrium
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Propargylic C(sp3) - H bond activation of 1-substituted-1-propynes, such as 1-trimethylsilyl-1-propyne, 2-hexyne, and 1-phenyl-1-propyne, was achieved by treatment with an alkylyttrium complex 8 bearing an ene-diamido ligand to give the corresponding (η3-propargyl/allenyl)yttrium complexes 7a-c. A unique delocalized η3-propargyl/allenyl structure of these three complexes was revealed by NMR spectroscopy and X-ray single crystal analyses. To elucidate the reactivity of the η3-propargyl/allenyl unit of complexes 7a-c, we conducted two reactions with N-methylaniline and N,N′-dicyclohexylcarbodiimine. For protonation by N-methylaniline, we found that the product distribution of monosubstituted internal alkynes and allenes depended on the substituent on the η3-propargyl/allenyl moiety: 7a and 7b afforded the corresponding internal alkynes as the major products, whereas the major protonation product of 7c was phenylallene. For the insertion of N,N′-dicyclohexylcarbodiimine, complex 7a selectively yielded η3-{N,N′-dicyclohexyl-2-(3-trimethylsilylpropargyl)amidinate}yttrium 12a, while complex 7c produced η3-{N,N′-dicyclohexyl-2-(1-phenylallenyl)amidinate}yttrium complex 13c, though complex 7b gave a mixture of η3-{N,N′-dicyclohexyl-2-(3-normalpropylpropargyl)amidinate}yttrium complex 12b and η3-{N,N′-dicyclohexyl-2-(1-normalpropylallenyl)amidinate}yttrium 13b in an 83:17 ratio. On the basis of the product distributions in these two-types of reactions, (η3-propargyl/allenyl)yttrium complexes were shifted into preferentially favorable η1-allenyl species or η1-propargyl species depending on the substituents prior to the reaction with electrophiles via a four-membered cyclic mechanism.
- Nagae, Haruki,Kundu, Abhinanda,Tsurugi, Hayato,Mashima, Kazushi
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p. 3061 - 3067
(2017/09/05)
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- Catalytic carbonylative rearrangement of norbornadiene via dinuclear carbon-carbon oxidative addition
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Single bonds between carbon atoms are inherently challenging to activate using transition metals; however, ring-strain release can provide the necessary thermodynamic driving force to make such processes favorable. In this report, we describe a strain-induced C-C oxidative addition of norbornadiene. The reaction is mediated by a dinuclear Ni complex, which also serves as a catalyst for the carbonylative rearrangement of norbornadiene to form a bicyclo[3.3.0] product.
- Hartline, Douglas R.,Zeller, Matthias,Uyeda, Christopher
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supporting information
p. 13672 - 13675
(2017/11/07)
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- Palladium-catalyzed allylation of tautomerizable heterocycles with alkynes
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A method for the allylic amidation of tautomerizable heterocycles was developed by a palladium catalyzed allylation reaction with 100% atom economy. A series of structurally diverse N-allylic substituted heterocycles can be synthesized in good yields with high chemo-, regio-, and stereoselectivities under mild conditions.
- Lu, Chuan-Jun,Chen, Dong-Kai,Chen, Hong,Wang, Hong,Jin, Hongwei,Huang, Xifu,Gao, Jianrong
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p. 5756 - 5763
(2017/07/22)
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- Palladium-Catalyzed Synthesis of Alkynes via a Tandem Decarboxylation/Elimination of (E)-Enol Triflates
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A mild catalytic synthesis of alkynes via a tandem Pd-catalyzed decarboxylation/elimination of enol triflates is described. Key attributes of the method include readily available starting materials, broad functional group tolerance, and the ability to access terminal, internal, and halogenated alkynes. The preliminary scope of the reaction is demonstrated on 25 different examples with yields ranging from 63% to 96%.
- Munteanu, Charissa,Frantz, Doug E.
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supporting information
p. 3937 - 3939
(2016/08/30)
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- Palladium-Catalyzed Dearomative Allylic Alkylation of Indoles with Alkynes to Synthesize Indolenines with C3-Quarternary Centers
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A palladium-catalyzed dearomative allylic alkylation of indoles with alkynes to construct indolenines with C3-quarternary centers was reported. The in situ formed arylallene intermediate omitted the need to install leaving groups on the allylic compounds and employ extra oxidants to oxidize the allylic C-H bonds. The reaction exhibited good functional group tolerance and high atom economy. Moreover, the reaction was further expanded to synthesize pyrroloindolines and furanoindolines.
- Gao, Shang,Wu, Zijun,Fang, Xinxin,Lin, Aijun,Yao, Hequan
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supporting information
p. 3906 - 3909
(2016/08/16)
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- Copper(II)-catalyzed highly regio- and stereoselective hydrosilylation of unactivated internal alkynes with silylborate in water
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The highly regio- and stereoselective hydrosilylation of internal alkynes with silylborate catalyzed by Cu(OTf)2 with 1,10-phenanthroline as the ligand in the presence of Cs2CO3 in water is developed. This protocol was applied efficiently in the aqueous synthesis of multi-substituted vinylsilanes.
- Xuan, Qing-Qing,Ren, Chuan-Li,Liu, Li,Wang, Dong,Li, Chao-Jun
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supporting information
p. 5871 - 5874
(2015/06/08)
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- Copper-catalyzed radical reaction of N -tosylhydrazones: Stereoselective synthesis of (E)-vinyl sulfones
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A new chemistry of hydrazines that is a copper-catalyzed radical reaction to synthesize vinyl sulfones from readily available N-tosylhydrazones has been described. The protocol provides a novel strategy for the synthesis of various vinyl sulfones including α, β-disubstituted ones and terminal ones. The advantages of the transformation include excellent E stereoselectivity, broad substrate scope, low cost of reagents, and convenient operation. A novel and efficient one-pot synthesis of alkynes from N-tosylhydrazones has been achieved. The studies provide important complementary approaches for the syntheses of vinyl sulfones and alkynes.
- Mao, Shuai,Gao, Ya-Ru,Zhu, Xue-Qing,Guo, Dong-Dong,Wang, Yong-Qiang
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p. 1692 - 1695
(2015/04/14)
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- Organomagnesium-catalyzed isomerization of terminal alkynes to allenes and internal alkynes
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Organomagnesium complexes 2 were synthesized from N,N-dialkylamineimine ligands 1 and dibenzylmagnesium by benzylation of the imine moiety. 3-Aryl-1-propynes reacted with 2 to form the corresponding tetraalkynyl complexes, which acted as catalysts for the transformation of these terminal alkynes into allenes and further to internal alkynes under mild conditions. To the best of our knowledge, this example is the first of an organomagnesium-catalyzed isomerization of alkynes. Notably, the reactions proceeded through temporally separated autotandem catalysis, thus allowing the isolation of the allene or internal alkyne species in good yields. Mechanistic experiments suggested that the catalytically active tetraalkynyl complexes consist of a tautomeric mixture of alkynyl-, allenyl-, and propargylmagnesium species.
- Rochat, Rapha?l,Yamamoto, Koji,Lopez, Michael J.,Nagae, Haruki,Tsurugi, Hayato,Mashima, Kazushi
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supporting information
p. 8112 - 8120
(2015/05/27)
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- Catalysts for the alkyne metathesis
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Organometallic compounds of the general formula (I), in which M=Mo, W, are claimed.
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Page/Page column 27; 28; 50
(2015/04/15)
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- Copper-catalyzed aerobic oxidative transformation of ketone- Derived N-tosyl hydrazones: An entry to alkynes
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A novel strategy involving Cu-catalyzed oxidative transformation of ketone-derived hydrazone moiety to various synthetic valuable internal alkynes and diynes has been developed. This method features inexpensive metal catalyst, green oxidant, good functional group tolerance, high regioselectivity and readily available starting materials. Oxidative deprotonation reactions were carried out to form internal alkynes and symmetrical diynes. Cross-coupling reactions of hydrazones with halides and terminal alkynes were performed to afford functionalized alkynes and unsymmetrical conjugated diynes. A mechanism proceeding through a Cu-carbene intermediate is proposed for the CC triple bond formation.
- Li, Xianwei,Liu, Xiaohang,Chen, Huoji,Wu, Wanqing,Qi, Chaorong,Jiang, Huanfeng
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p. 14485 - 14489
(2015/02/05)
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- Synthesis of internal alkynes by Pd(PPh3)4/TMEDA-catalyzed Kumada cross-coupling of alkynyl halides with grignard reagents
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Alkynes serve as prevalent intermediates in the synthesis of natural products and pharmaceuticals. We here described a new and efficient route to internal alkynes by Pd-catalyzed Kumada cross-coupling reactions of alkynyl halides with Grignard reagents. In the presence of Pd(PPh3)4 and N 1,N 1,N 2,N 2-tetramethylethane-1,2-diamine (TMEDA), a variety of alkynyl halides underwent Kumada coupling with Grignard reagents, giving the corresponding internal alkynes in moderate to good yields. A new Pd-catalyzed Kumada cross-coupling reaction of alkynyl halides with Grignard reagents has been developed. This transformation provides a new, experimentally simple access to internal alkynes in good yields, and it can accommodate a broad range of substrates with excellent functional group tolerance and good levels of selectivity control.
- Zhang, Mao-Mei,Gong, Jun,Song, Ren-Jie,Li, Jin-Heng
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p. 6769 - 6773
(2016/02/18)
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- Reactions of phenylethynyl cuprates of lanthanides with organyl halides and synthesis of the related polyfunctional compounds
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Phenylethynyl cuprate complexes of lanthanides react with organyl halides RX, Ph3CX, R3SiX, and RC(O)X (X = Cl, I; R = alkyl) in tetrahydrofuran to give polyfunctional organic and hetero-organic compounds with high yield. The reactio
- Zhil'tsov,Druzhkova,Dydykina,Makarov
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p. 2167 - 2173
(2015/02/05)
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- Conjugated BODIPY DYEmers by metathesis reactions
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Boron dipyrrin (BODIPY) DYEmers bridged by conjugating ethynylene and ethenylene moieties can be prepared through metal-promoted metathesis reactions. Alkyne metathesis was advantageous over alkene metathesis and Stille coupling for BODIPY substrates, but also showed specific restrictions with respect to steric encumbrance and regioselectivity. All derivatives with unhindered rotations along the bridges reside in a coplanar minimum conformation. For a hindered β-ethenylene-bridged DYEmer, the shifts in the 1HNMR spectrum indicate a significant loss of coplanarity and conjugation. The electronic interactions of the BODIPY subchromophores, visualized by optical spectra and cyclic voltammograms, deviate significantly from those found for nonconjugated and excitonically coupled DYEmers. The observed properties can be rationalized in each case by the respective strength of conjugation through the α or β position, the degree of coplanarity, and conformational dynamics. Metal-promoted metathesis is a valuable tool for the efficient syntheses of conjugated di- and oligochromophoric boron dipyrrin (BODIPY) systems (see figure). The BODIPY DYEmers prepared display interesting photophysical properties and show promise in current optoelectronic research.
- Ahrens, Johannes,Haberlag, Birte,Scheja, Anne,Tamm, Matthias,Broering, Martin
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p. 2901 - 2912
(2014/03/21)
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- Palladium-catalyzed methylation of alkynyl C(sp)-H bonds with dimethyl sulfonium ylides
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A novel palladium-catalyzed methylation protocol for the synthesis of methyl-functionalized internal alkynes has been established. This methylation method is achieved through a C(sp)-C(sp3) bond formation process and represents a new synthetic application of sulfonium ylides.
- Liu, Yan-Yun,Yang, Xu-Heng,Huang, Xiao-Cheng,Wei, Wen-Ting,Song, Ren-Jie,Li, Jin-Heng
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p. 10421 - 10426
(2013/11/06)
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- Theoretical support for the involvement of a radical pathway in the formation of allenylzincs from propargyl iodides and dialkylzincs: Influence of zinc coordination
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Propargyl iodides are good precursors for allenylzincs via reaction with diethylzinc, even in nondegassed medium. These reactions proceed via zinc/iodine exchange. Owing to the previously reported detection of propargyl radical by ESR experiments, in this process a radical mechanism was suspected. Calculations of the C-Zn BDEs in allenyl- and propargylzinc species were performed with the CBS-QB3 method to demonstrate that propargyl radicals could undergo homolytic substitution at zinc. The stabilization of allenylzinc derivatives by chelation, made possible by the selection of appropriate ortho-substituted 3-phenylalkynyl iodides as precursors, was shown to influence the regioselectivity of their addition to aldehydes and ketones. The more stabilized the chelated allenylzinc intermediate, the higher the ratio of homopropargylic alcohols.
- Jammi, Suribabu,Mouysset, Dominique,Siri, Didier,Bertrand, Michèle P.,Feray, Laurence
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p. 1589 - 1603
(2013/04/10)
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- Arylsulfonylacetylenes as alkynylating reagents
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The unexpected anti-Michael addition of RLi to β-substituted sulfonylacetylenes, followed by in situ elimination of the ion sulfinate, allows the alkynylation of C(sp2) and C(sp3). Aryl and heteroaryl acetylenes, enynes, and mono and dialkyl alkynes can be obtained in very high yields under very mild conditions, avoiding the use of transition metals as catalysts and, in many cases, haloderivatives as starting materials. Furthermore, the use of lithium 2-p-tolylsulfinyl benzylcarbanions as nucleophiles of these reactions allows their stereocontrolled alkynylation, affording enantiomerically pure alkynes or enantioenriched allenes depending on the protonating agent (NH4Cl or H2O).
- Marzo, Leyre,Aleman, Jose,Garcia Ruano, Jose Luis
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p. 403 - 407
(2013/07/26)
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- Expanding the scope of arylsulfonylacetylenes as alkynylating reagents and mechanistic insights in the formation of Csp2-Csp and Csp 3-Csp bonds from organolithiums
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We describe the unexpected behavior of the arylsulfonylacetylenes, which suffer an "anti-Michael" addition of organolithiums producing their alkynylation under very mild conditions. The broad scope, excellent yields, and simplicity of the experimental procedure are the main features of this methodology. A rational explanation of all these results can be achieved by theoretical calculations, which suggest that the association of the organolithiums to the electrophile is a previous step of their intramolecular attack and is responsible for the unexpected "anti-Michael" reactions observed for substituted sulfonylacetylenes. A calculated conclusion: A new transition-metal-free strategy for the synthesis of any kind of alkynyl derivatives in high yields in the reaction of organolithium species with arylsulfonylacetylenes is presented (see scheme). Theoretical calculations provide a rational explanation and suggest that association of the organolithium to the electrophile is a previous step of their intramolecular attack and is responsible for the "anti-Michael" reaction. Copyright
- Garcia Ruano, Jose Luis,Aleman, Jose,Marzo, Leyre,Alvarado, Cuauhtemoc,Tortosa, Mariola,Diaz-Tendero, Sergio,Fraile, Alberto
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supporting information; experimental part
p. 8414 - 8422
(2012/07/27)
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- Silver triflate-catalyzed cyclopropenation of internal alkynes with donor-/acceptor-substituted diazo compounds
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Silver triflate was found to be an efficient catalyst for the cyclopropenation of internal alkynes using donor-/acceptor-substituted diazo compounds as carbenoid precursors. Highly substituted cyclopropenes, which cannot be synthesized directly via rhodium(II)-catalyzed carbenoid chemistry, can now be readily accessed.
- Briones, John F.,Davies, Huw M. L.
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supporting information; experimental part
p. 3984 - 3987
(2011/09/16)
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- Enantioselective synthesis of β-substituted cyclic ketones via cobalt-catalyzed asymmetric reductive coupling of alkynes with alkenes
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A CoI2/(R)-BINAP, Zn, ZnI2, H2O system efficiently catalyzes the intermolecular asymmetric reductive coupling of alkynes with cyclic enones to afford highly regioand enantioselective β-alkenyl cyclic ketones. A possible mechanism that involves the formation of a cobaltacyclopentene intermediate from the alkyne and cyclic enone is proposed.
- Wei, Chu-Hung,Mannathan, Subramaniyan,Cheng, Chien-Hong
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supporting information; body text
p. 6942 - 6944
(2011/06/19)
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- Fritsch-Buttenberg-Wiechell rearrangement to alkynes from gem-dihaloalkenes with lanthanum metal
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The first example of the FBW rearrangement using of lanthanum metal and a catalytic amount of iodine was disclosed. When gem-diiodo- and gem-dibromoalkenes were treated with lanthanum metal in the presence of a catalytic amount of iodine, the reductive dehalogenation of these compounds smoothly proceeded to produce the corresponding alkynes in moderate to good yields.
- Umeda, Rui,Yuasa, Takumi,Anahara, Namika,Nishiyama, Yutaka
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supporting information; experimental part
p. 1916 - 1919
(2011/05/14)
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- Thermal rearrangement of thiocarbonyl-stabilised triphenylphosphonium ylides leading to (Z)-1-diphenylphosphino-2-phenylsulfenylalkenes
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While thermolysis of thiocarbonyl-stabilised phosphonium ylides generally results in extrusion of Ph3PS to give alkynes, those with a PCH function instead undergo a novel P to S transfer of a phenyl group to give (Z)-configured 1-phosphino-2-su
- Alan Aitken,Dawson, Graham,Keddie, Neil S.,Kraus, Helmut,Slawin, Alexandra M. Z.,Wheatley, Joanne,Woollins, J. Derek
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body text
p. 7381 - 7383
(2010/06/13)
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- Indole synthesis via rhodium catalyzed oxidative coupling of acetanilides and internal alkynes
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The oxidative synthesis of highly functionalized indoles from simple anilines and internal alkynes mediated by a rhodium(III) catalyst is described. Good yields are obtained for a variety of aniline substrates, and good regioselectivity is obtained for the more sterically accessible position when meta-substituted anilines are used. Symmetrical and unsymmetrical alkynes react efficiently with high (>40:1) C2/C3 regioselectivity when aryl/alkyl substituted alkynes are used. Copyright
- Stuart, David R.,Bertrand-Laperle, Megan,Burgess, Kevin M. N.,Fagnou, Keith
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supporting information; experimental part
p. 16474 - 16475
(2009/04/13)
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- METHOD FOR MAKING BIARYL COMPOUNDS, COMPOUNDS MADE BY THE METHOD, AND METHOD FOR THEIR USE
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Certain disclosed embodiments of the present invention concern a method for making biaryl compounds by combining a diene with a dienophile under reaction conditions that facilitate a Diels-Alder reaction. Certain embodiments are particularly directed to making a tetra-ortho-substituted biaryl compounds. The disclosed method may involve using novel dienes, dienophiles, or both. Similarly, certain of the biaryl compounds are novel compounds too. Additional disclosed embodiments concern a method for making useful compounds by first making a Diels-Alder adduct. The Diels-Alder adduct is then further modified or coupled to other compounds. The method can be used to make carbazoles, such as Siamenol. Disclosed biaryl compounds are useful for a number of applications, such as pharmacophores and organocatalysts.
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Page/Page column 45-46
(2009/01/23)
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- A versatile one-pot synthesis of 4-aryl-1,5-disubstituted 1,2,3-triazoles via 1,3-dipolar cycloaddition followed by Negishi reaction under new conditions
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Several derivatives of 4-aryl-1,5-disubstituted 1,2,3-triazole were synthesized in good yields via 1,3-dipolar cycloaddition followed by Negishi reaction under new conditions. Georg Thieme Verlag Stuttgart.
- Akao, Atsushi,Tsuritani, Takayuki,Kii, Satoshi,Sato, Kimihiko,Nonoyama, Nobuaki,Mase, Toshiaki,Yasuda, Nobuyoshi
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- Convenient synthesis of (1-propynyl)arenes through a one-pot double elimination reaction, and their conversion to enynes
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A series of (1-propynyl)arenes were prepared by one-pot double elimination reaction of ethyl sulfone, aromatic aldehyde and chloro diethylphosphate in THF with a base such as BuLi and t-BuOK. A propargyllithium which was prepared by treatment of (1-propynyl)arene with BuLi in the presence of 1,3-dimethyl-3,4,5, 6-tetrahydro-2(1H)-pyrimidinone (DMPU) reacted with aromatic aldehyde, chloro diethylphosphate and t-BuOK to afford (4-arylbut-3-en-1-ynyl)arene. Photoluminescence of the enynes thus prepared was recorded both in solution and in the solid state. Georg Thieme Verlag Stuttgart.
- An, De-Lie,Zhang, Zhiyang,Orita, Akihiro,Mineyama, Hidetaka,Otera, Junzo
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p. 1909 - 1912
(2008/03/13)
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