- Sodium Phenoxide Mediated Hydroxymethylation of Alkynylsilanes with N-[(Trimethylsiloxy)methyl]phthalimide
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The hydroxymethylation of alkynylsilanes with formaldehyde generated in situ from N-[(trimethylsiloxy)methyl]phthalimide proceeds in the presence of a stoichiometric amount of NaOPh. The reaction occurs at room temperature by using an operationally simple one-step procedure. A variety of alkynylsilanes possessing electron-donating, electron-withdrawing, and halogen groups (including heteroaryl-substituted alkynylsilanes) provide hydroxymethylated products.
- Asano, Narumi,Sasaki, Keita,Chataigner, Isabelle,Shigeno, Masanori,Kondo, Yoshinori
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- Synthesis of Substituted 1-Alkylidenephthalanes via Lithium-Promoted 5-exo-dig Cyclization
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A one-pot synthesis of 1-alkylidenephthalanes from 3-(2-bromophenyl)propyne derivatives has been developed. 3-(2-Bromophenyl)propynal acetals 9 and corresponding orthoester 19 were treated successively with n-butyllithium and various aldehydes and ketones at low temperature to obtain 1-alkylidenephthalanes 10 and 20 with various functional groups at the exocyclic methylene moiety. Halogen-metal exchange, nucleophilic addition to various carbonyl compounds, regioselective 5-exo-dig cyclization of the respective intermediate lithium alcoholate and hydrolysis represent the key steps in this Domino reaction. A two-step mechanism involving at first a synchronous cyclization to form a vinyllithium intermediate and then a methoxide elimination leading to the respective 1-methoxy allenes is suggested based on DFT-calculations.
- Bunse, Paul,Würthwein, Ernst-Ulrich,Wünsch, Bernhard
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- Oxidative cyclization of 2-allenyl-1,1′-biphenyls with α-carbonyl alkyl bromides: Facile access to functionalized phenanthrenes
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A new copper-facilitated oxidative cyclization of 2-allenyl-1,1′-biphenyls with α-carbonyl alkyl bromides for producing functionalized phenanthrenes is presented, which represents the first allene 2,3-dicarbofunctionalization triggered by oxidative radical-medicated C3-addition of the terminal allene moiety and C-Br/C-H functionalization.
- Wang, Cheng-Yong,Pan, Gao-Hui,Chen, Fan,Li, Jin-Heng
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- Synthesis and biological activity of new arenediyne-linked isoxazolidines
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Arenediyne-isoxazolidine conjugates have been synthesized as a new scaffold for the development of bioactive mimics. Some of the synthesized compounds are endowed with antiproliferative activity against three human cancer cell lines. Their thermal reactiv
- Romeo, Roberto,Navarra, Michele,Giofre, Salvatore V.,Carnovale, Caterina,Cirmi, Santa,Lanza, Giuseppe,Chiacchio, Maria A.
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- Synthesis of Azepino[1,2-a]indole-10-amines via [6+1] Annulation of Ynenitriles with Reformatsky Reagent
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Lewis acid-catalyzed [6+1] annulation reactions of 2-cyano-1-propargyl- and 2-alkynyl-1-cyanomethyl-indoles with Reformatsky reagent are described. 8-Aryl, 8-alkyl-, 8-hetaryl-, 9-aryl, and 9-alkyl-azepino[1,2-a]indole amines were obtained through a 7-endo-mode cyclization of the β-aminoacrylate intermediates. The antiproliferative activity of the azepino[1,2-a]indoles analogs against the HCT-116 cells were also examined.
- Iioka, Ryoya,Yorozu, Kohei,Sakai, Yoko,Kawai, Rika,Hatae, Noriyuki,Takashima, Katsuki,Tanabe, Genzoh,Wasada, Hiroaki,Yoshimatsu, Mitsuhiro
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supporting information
p. 1553 - 1558
(2021/02/26)
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- One-pot synthesis of 3-substituted-4H-[1,2,3] triazolo[5,1-c][1,4]oxazin-6(7H)-ones from propargyl alcohols, chloroacetyl chloride, and sodium azide
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An efficient, one-pot synthesis of 3-substituted-4H-[1,2,3]triazolo[5,1-c][1,4]oxazin-6(7H)-ones is developed via sequential esterification, substitution, and 1,3-dipolar cycloaddition processes of various propargyl alcohols, chloroacetyl chloride, and so
- Chen, Jun-Min,Liu, Xiao-Ling,Sheng, Shou-Ri,Wei, Mei-Hong,Zhang, Xiao-Lan
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p. 482 - 485
(2020/11/30)
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- Gold(I)-Catalyzed Cascade Cyclization Reactions of Allenynes for the Synthesis of Fused Cyclopropanes and Acenaphthenes
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A gold-catalyzed reaction of phenylene-tethered allenynes with benzofurans gave 1-(naphth-1-yl)cyclopropa[b]benzofuran derivatives, whereas the reaction of 1-allenyl-2-ethynyl-3-methylbenzene derivatives in the absence of benzofurans gave acenaphthenes in good yields. These results can be rationalized by nucleophilic attack of the alkyne moiety on an activated allene to form a vinyl cation intermediate.
- Ikeuchi, Takaya,Inuki, Shinsuke,Oishi, Shinya,Ohno, Hiroaki
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supporting information
p. 7792 - 7796
(2019/05/15)
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- Development of a telescoped flow process for the safe and effective generation of propargylic amines
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Propargylic amines are important multifunctional building blocks that are frequently exploited in the synthesis of privileged heterocyclic entities. Herein we report on a novel flow process that achieves the safe and effective on-demand synthesis of propargylic amines in a telescoped manner. This process minimizes exposure to hazardous azide intermediates and renders a streamlined route into these building blocks. The value of this approach is demonstrated by the rapid generation of a small selection of drug-like thiazolines that result from a high-yielding reaction cascade between propargylic amines with different aryl isothiocyanates.
- Donnelly, Kian,Zhang, Huan,Baumann, Marcus
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- Benzo[b]tellurophenes as a potential histone H3 lysine 9 demethylase (KDM4) inhibitor
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Gene expression and tumor growth can be regulated by methylation levels of lysine residues on histones, which are controlled by histone lysine demethylases (KDMs). Series of benzo[b]tellurophene and benzo[b]selenophene compounds were designed and synthesi
- Choi, Yong-Sung,Jeong, Jin-Hyun,Kim, Yoon-Jung,Kwon, So Hee,Lee, Dong Hoon
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- Metal-Free Regioselective Chloroazidation of Internal Alkynes
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A metal-free, room temperature protocol for the regioselective chloroazidation of internal alkynes is disclosed. The reactions of internal alkynes with trimethylsilyl azide (TMSN3) in the presence of 1,3-dichloro-5,5-dimethylhydantoin (DCDMH) afforded the corresponding chloroazidoalkenes in good yields. This reaction has good functional group tolerance and is operationally simple.
- Huang, Bin,Liffert, Raphael,Linden, Anthony,Gademann, Karl
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supporting information
p. 981 - 984
(2019/01/04)
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- Copper-catalyzed [1,2]-rearrangements of allylic iodides and aryl α-diazoacetates
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The [1,2]- and [2,3]-rearrangements of iodonium ylides are synthetically useful reactions for the generation of functionalized α-iodoesters. Allylic iodides are coupled with α-diazoesters in the presence of a copper catalyst and a ligand to generate iodonium ylides, which undergo metal-mediated rearrangements. By fine-tuning the structure of the ligand, we have reversed the regioselectivity of copper-catalyzed reactions of iodonium ylides from [2,3]- to [1,2]-rearrangements with the use of alternate bipyridine ligands. The preference for [1,2]-rearrangements was further improved by using bulky aryl α-diazoester substrates. Several α-iodoesters with a diverse range of functional groups were generated in good yields (up to 88% yield) and high regioselectivities (up to >95:5 regioisomeric ratio). A deuterium-labeled substrate was utilized to gain insight into the mechanism of the reaction.
- Xu, Bin,Gartman, Jackson A.,Tambar, Uttam K.
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p. 4150 - 4159
(2017/06/29)
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- Copper-Catalyzed Enantio-, Diastereo-, and Regioselective [2,3]-Rearrangements of Iodonium Ylides
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The first highly enantioselective, diastereoselective, and regioselective [2,3]-rearrangement of iodonium ylides has been developed as a general solution to catalytic onium ylide rearrangements. In the presence of a chiral copper catalyst, substituted allylic iodides couple with α-diazoesters to generate metal-coordinated iodonium ylides, which undergo [2,3]-rearrangements with high selectivities (up to >95:5 r.r., up to >95:5 d.r., and up to 97 % ee). The enantioenriched iodoester products can be converted stereospecifically into a variety of onium ylide rearrangement products, as well as compounds that are not accessible by classical onium ylide rearrangements.
- Xu, Bin,Tambar, Uttam K.
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supporting information
p. 9868 - 9871
(2017/08/08)
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- Palladium-catalyzed multicomponent reaction (MCR) of propargylic carbonates with isocyanides
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A palladium-catalyzed multicomponent reaction (MCR) of propargylic carbonates with isocyanides is reported. Remarkably, the orderly insertion of isocyanides affords two types of valuable N-heterocyclic products (Z)-6-imino-4,6-dihydro-1H-furo[3,4-b]pyrrol-2-amines and (E)-5-iminopyrrolones in high yields. Systematic analysis of the reaction conditions indicates that the selectivity of these N-heterocyclic products can be controlled by ligands and temperature.
- Peng, Jianwen,Gao, Yang,Hu, Weigao,Gao, Yinglan,Hu, Miao,Wu, Wanqing,Ren, Yanwei,Jiang, Huanfeng
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supporting information
p. 5924 - 5927
(2016/11/29)
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- Co2(CO)8-mediated Selective Reductions of Propargyl Alcohol Derivatives to Alkenes
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In the presence of Co2(CO)8 and additives, propargyl alcohol derivatives could be reduced to alkenes in moderate to good yield. The selectivity of this reaction could be controlled by adding different additives: with H2O as the additive, the major configuration of product is Z-alkene; with CF3COOH as the additive, the major configuration of product is E-alkene.
- Dou, Ying,Xing, Ping,Huang, Zuogang,Jiang, Biao
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supporting information
p. 999 - 1002
(2016/02/18)
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- Gold and palladium combined for the Sonogashira coupling of aryl and heteroaryl halides
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A highly efficient gold and palladium combined methodology for the Sonogashira coupling of a wide array of electronically and structurally diverse aryl and heteroaryl halides is described. The orthogonal reactivity of the two metals shows high selectivity and extreme functional group tolerance in Sonogashira coupling. A brief mechanistic study reveals that the gold acetylide intermediate enters into the palladium catalytic cycle at the transmetalation step. Georg Thieme Verlag Stuttgart.New York.
- Panda, Biswajit,Sarkar, Tarunk.
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p. 817 - 829
(2013/04/10)
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- Experimental and computational evidence for gold vinylidenes: Generation from terminal alkynes via a bifurcation pathway and facile C-H insertions
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Facile cycloisomerization of (2-ethynylphenyl)alkynes is proposed to be promoted synergistically by two molecules of BrettPhosAuNTf2, affording tricyclic indenes in mostly good yields. A gold vinylidene is most likely generated as one of the reaction intermediates on the basis of both mechanistic studies and theoretical calculations. Different from the well-known Rh, Ru, and W counterparts, this novel gold species is highly reactive and undergoes facile intramolecular C(sp3)-H insertions as well as O-H and N-H insertions. The formation step for the gold vinylidene is predicted theoretically to be complex with a bifurcated reaction pathway. A pyridine N-oxide acts as a weak base to facilitate the formation of an alkynylgold intermediate, and the bulky BrettPhos ligand in the gold catalyst likely plays a role in sterically steering the reaction toward formation of the gold vinylidene.
- Ye, Longwu,Wang, Yanzhao,Aue, Donald H.,Zhang, Liming
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supporting information; experimental part
p. 31 - 34
(2012/02/15)
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- Lactone radical cyclizations and cyclization cascades mediated by SmI 2-H2O
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Unsaturated lactones undergo reductive radical cyclizations upon treatment with SmI2-H2O to give decorated cycloheptanes in a single highly selective operation during which up to three contiguous stereocenters are generated. Furthermore, cascade processes involving lactones bearing two alkenes, an alkene and an alkyne, or an allene and an alkene allow "one-pot" access to biologically significant molecular scaffolds with the construction of up to four contiguous stereocenters. The cyclizations proceed by the trapping of radical anions formed by electron transfer reduction of the lactone carbonyl.
- Parmar, Dixit,Matsubara, Hiroshi,Price, Kieran,Spain, Malcolm,Procter, David J.
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supporting information; experimental part
p. 12751 - 12757
(2012/09/05)
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- Iron(II) chloride catalyzed alkylation of propargyl ethers: Direct functionalization of an sp3 C-H bond adjacent to oxygen
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Iron(II) chloride catalyzed direct alkylation of sp3 C-H bond adjacent to oxygen in propargyl ethers has been accomplished by the use of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as oxidant under mild reaction conditions. The reaction proceeded smoothly with a variety of 1,3-diketones leading to -dicarbonyl ether in moderate yields. In the absence of 1,3-diketones, ynenones were produced by the use of iron(III) chloride and DDQ. Georg Thieme Verlag Stuttgart - New York.
- Xie, Yongju,Yu, Ming,Zhang, Yuhong
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supporting information; experimental part
p. 2803 - 2809
(2011/10/09)
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- Gold-catalyzed annulation/fragmentation: Formation of free gold carbenes by retro-cyclopropanation
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The gold(I)-catalyzed cyclization of 1-(prop-2-yn-1-yl)-2-alkenylbenzenes substituted at the benzylic position with OR groups gives 1,3-disubstituted naphthalenes with concomitant fragmentation of the alkene. One of these annulations proceeds by a retro-cyclopropanation that leads to free gold(I) carbenes.
- Solorio-Alvarado, Cesar R.,Echavarren, Antonio M.
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supporting information; experimental part
p. 11881 - 11883
(2010/10/19)
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- On the catalytic duo PdCl2(PPh3)2/AuCl(PPh3) that cannot effect a Sonogashira-type reaction: a correction
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In contrast to the observation made by the Laguna group, we report that the combination of PdCl2(PPh3)2 and AuCl(PPh3) makes a unique catalytic system that allows Sonogashira-type cross-coupling of both aryl and alkyl alkynes with aryl halides in excellent yields.
- Panda, Biswajit,Sarkar, Tarun K.
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experimental part
p. 301 - 305
(2010/03/26)
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- The effect of charge-transfer complexation/π-stacking interactions in lowering the activation barrier of the Bergman cyclization
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To elaborate the concept of weak interactions and their effect on Bergman Cyclization (BC), several 1,2-dikynyl benzenes incorporating various combinations of donor and acceptor units in the two arms of the enediynes were designed and synthesized, and the
- Basak, Amit,Bag, Subhendu Sekhar,Das, Amit K.
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p. 1239 - 1245
(2007/10/03)
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- Nitrogen substituted cyclic enediynes: Synthesis, thermal reactivity and coniplexation with metal ions
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A number of N-substituted cyclic enediynes (azaenediynes) have been synthesized via Pd(0)-catalysed ene-yne coupling followed by N-alkylation. The simplest of them, a 10-membered monocyclic enediyrie 1, underwent Bergman cyclization (BC) at 23°C with a half-life of 72 h. The kinetics of BC slowed down considerably by fusing a benzene ring onto the enediyne. Several novel bis(azaenediyne)s and bis(diazaenediyne)s 3-6 have been synthesized. Their onset temperatures for BC were lowered under metal ion complexation conditions. The Royal Society of Chemistry 2000.
- Basak, Amit,Shain, Jagadish Chandra,Khamrai, Uttam Kumar,Rudra, Kakali Rani,Basak, Ajoy
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p. 1955 - 1964
(2007/10/03)
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- Synthesis and thermal reactivity of a novel macrocyclic enediyne and its copper(II) complex
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A novel 24-membered tetraazaenediyne and its copper(II) complex have been synthesized via a Pd(0)-catalysed macrocyclization route. DSC measurements revealed a lowering of onset temperature for Bergman Cyclization upon complexation.
- Basak, Amit,Shain, Jagadish Chandra
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p. 3029 - 3030
(2007/10/03)
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- THE SYNTHESIS OF 11-13 MEMBERED DIACETYLENIC AND 18-MEMBERED TETRAACETYLENIC RING SYSTEMS
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The sysnthesis of title compounds is described, starting from o-dibromobenzene.The palladium catalysed coupling of the latter with acetylenes occurred in a step-wise fashion, when no cocatalyst (CuI) was used.
- Just, George,Singh, Rina
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p. 5981 - 5984
(2007/10/02)
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