29539-10-4Relevant academic research and scientific papers
Gold-catalyzed benzylic C-H activation at room temperature
Hashmi, A. Stephen K.,Schaefer, Sascha,Woelfle, Michael,Gil, Cesar Diez,Fischer, Peter,Laguna, Antonio,Blanco, M. Carmen,Gimeno, M. Concepcion
, p. 6184 - 6187 (2007)
(Chemical Equation Presented) A tale of the unexpected: Coordinating and potentially chelating groups allow gold-catalyzed benzylic C-H activation at room temperature. Substrates with additional nucleophilic substituents undergo unexpected dimerizations,
Selective Approaches to α- and β-Arylated Vinyl Ethers
Bolm, Carsten,Domzalska-Pieczykolan, Anna,Funes-Ardoiz, Ignacio,Furman, Bart?omiej
supporting information, (2021/11/30)
We developed simple and efficient protocols for palladium-catalyzed regioselective α- and β-arylations of structurally diverse vinyl ethers. Both catalytic methods proceed under relatively mild reactions conditions applying to a broad substrate range including more complex compounds providing arylated glucal or isochromene. Lacking the common requirement of a large reagent excess, the transformations are highly economic and limiting the waste production. Results from computational studies (DFT) provided insight into the key factors determining the pronounced regioselectivities of the investigated reactions.
Synthesis of 2-Aryl Acetophenones via Hydrobromination and Oxy-isomerization of (o-Arylethynyl)benzyl Alcohols
Kuan, Tzu-Hsuan,Hou, Duen-Ren
, p. 6907 - 6917 (2021/05/06)
Hydrobromination and oxy-isomerization of (o-arylethynyl)benzyl alcohols to yield brominated aryl ketones were achieved with bromotrimethylsilane. The substrate scope suggested that vinyl carbocations, stabilized by the conjugated aryl groups, are the rea
Gold-Catalyzed Carbocyclization/C=N Bond Formation Cascade of Alkyne-Tethered Diazo Compounds with Benzo[c]isoxazoles for the Assembly of 4-Iminonaphthalenones and Indenes
Bao, Ming,Xie, Xiongda,Hu, Wenhao,Xu, Xinfang
supporting information, p. 4018 - 4023 (2021/07/10)
A gold-catalyzed carbocyclization/C=N bond formation cascade reaction has been developed for the synthesis of polyfunctionalized 4-iminonaphthalenones and indenes in good to high yields under mild reaction conditions. The reaction goes through 5/6-endo-di
Addition of benzyl ethers to alkynes: A metal-free synthesis of 1: H -isochromenes
Chen, Cheng-Chun,Hou, Duen-Ren,Kotipalli, Trimurtulu,Kuan, Tzu-Hsuan
, p. 10390 - 10402 (2021/12/17)
Bromotrimethylsilane (TMSBr)-promoted intramolecular cyclization of (o-arylethynyl)benzyl ethers to form 1H-isochromenes at room temperature is reported. Further studies indicated that vinyl carbocations are the reaction intermediates which are stabilized by the conjugated aryl groups. Thus, O-addition of benzyl ethers/tetrahydropyrans to alkynes was achieved under metal-free, acidic conditions. These reaction conditions were compatible with an alkynyl Prins reaction; therefore, 1H-isochromenes were produced directly from alkynyl benzaldehydes and alkynyl alcohols using a one-pot procedure. This journal is
FeCl3·6H2O-catalyzed facile and efficient synthesis of pyrano[4,3-b]quinolines and isochromenes
Asthana, Mrityunjaya,Singh, Jay Bahadur,Singh, Radhey M.
supporting information, p. 615 - 618 (2016/01/20)
An inexpensive 1 mol % FeCl3·6H2O reagent has been developed for the synthesis of 1,3-disubstituted 1H-pyrano[4,3-b]quinolines from o-arylethnylquinonylmethanol via 6-endo-dig cyclization of alcoholic -OH onto alkynes in good to excellent yields. The reaction conditions were successfully exploited on primary and tertiary alcohol analogs. The reagent was further generalized with the aromatic alcohol analogs providing the synthesis of isochromenes in good yields. The enhancement in the reaction rates and yields from primary to secondary to tertiary alcohols could be attributed to inductive effect of alkyl groups which enhanced the nucleophilicity of hydroxyl group and accelerated the cyclization mode.
Triaryl-Like MONO-, BIS-, and TRISKITPHOS Phosphines: Synthesis, Solution NMR Studies, and a Comparison in Gold-Catalyzed Carbon-Heteroatom Bond Forming 5-exo-dig and 6-endo-dig Cyclizations
Doherty, Simon,Knight, Julian G.,Perry, Daniel O.,Ward, Nicholas A. B.,Bittner, Dror M.,McFarlane, William,Wills, Corinne,Probert, Michael R.
supporting information, p. 1265 - 1278 (2016/06/01)
A homologous series of triaryl-like KITPHOS-type monophosphines containing one, two, or three bulky 12-phenyl-9,10-dihydro-9,10-ethenoanthracene (KITPHOS) units have been developed, and the influence of increasing steric bulk on their efficacy as ligands in gold(I)-catalyzed carbon-heteroatom bond-forming cyclizations has been investigated. Detailed solution NMR studies on Ph-TRISKITPHOS, its oxide, and the corresponding gold(I) chloride adduct identified a conformational exchange process involving a concerted librational motion of the individual anthracene-derived organic substituents about their P-C bonds. The cessation of this motion at reduced temperatures lowers the molecular symmetry such that the two C6H4 rings in each of the KITPHOS units become inequivalent; a lower energy process involving restricted rotation of the biaryl-like phenyl ring has also been identified. Electrophilic gold(I) complexes of these triaryl-like KITPHOS monophosphines catalyze the 5-exo-dig cycloisomerization of propargyl amides to afford the corresponding methylene oxazolines, which were used in a subsequent tandem carbonyl-ene reaction to afford functionalized 2-substituted oxazolines. A comparative survey revealed that catalyst efficiency for cycloisomerization decreases in the order MONOKITPHOS = BISKITPHOS > PPh3 > TRISKITPHOS. The optimum system also catalyzes the selective 6-endo-dig cyclization of 2-alkynylbenzyl alcohols, 2-alkynylbenzoic acid, and 2-phenylethynyl benzamides; gratifyingly, in several cases the yields obtained are markedly higher and/or reaction times significantly shorter than those previously reported for related gold catalysts. Moreover, these are the first examples of gold(I)-catalyzed 6-endo-dig cycloisomerizations involving 2-phenylethynyl benzamides and, reassuringly, the optimum gold(I)/MONOKITPHOS systems either rivaled or outperformed existing silver or palladium-based catalysts. The steric parameters of this homologous series of phosphines have been quantified and compared with selected triarylphosphines using a combination of Solid-G calculations, to determine the percentage of the metal coordination sphere shielded by the phosphine (the G parameter), and Salerno molecular buried volume calculations (SambVca) to determine the percent buried volume (%Vbur); the corresponding Tolman cone angles have also been determined from correlations.
Synthesis of Functionalized 1H-Isochromene Derivatives via a Au-Catalyzed Domino Cycloisomerization/Reduction Approach
Tomás-Mendivil, Eder,Starck, Jéro?me,Ortuno, Jean-Claude,Michelet, Véronique
, p. 6126 - 6129 (2016/01/09)
A Au-catalyzed versatile and efficient access to 1H-isochromenes is reported. The efficiency of the [AuCl2(Pic)] complex (1-5 mol %) was demonstrated and allowed a domino cycloisomerization/reduction reaction process starting from a wide range of functionalized ortho-alkynylbenzaldehydes and one example of ortho-alkynylpyridinylaldehyde. The smooth reaction conditions were amenable to aryl- and alkyl-substituted alkynyl derivatives, as well as functionalized halogen and ether moieties, leading to a chemo- and regioselective 6-endo-cyclization with good to excellent yields.
Regioselective synthesis of phthalans via Cu(OTf)2-catalyzed 5-exo-dig intramolecular hydroalkoxylation of 2-(ethynyl)benzyl alcohols
Praveen, Chandrasekaran,Iyyappan, Chandran,Perumal, Paramasivan Thirumalai
scheme or table, p. 4767 - 4771 (2010/09/20)
An efficient, regioselective Cu(OTf)2-catalyzed 5-exo-dig intramolecular hydroalkoxylation of 2-(ethynyl)benzyl alcohol, which provides a concise access to functionalized phthalan in high yields has been developed. A wide range of substrates po
Intramolecular alkyne hydroalkoxylation and hydroamination catalyzed by iridium hydrides
Li, Xingwei,Chianese, Anthony R.,Vogel, Tiffany,Crabtree, Robert H.
, p. 5437 - 5440 (2007/10/03)
(Chemical Equation Presented) Iridium(III) hydrides prove to be air-stable active catalysts for intramolecular hydroalkoxylation and hydroamination of internal alkynes with proximate nucleophiles. The cyclization follows highly selective 6-endo-dig regiochemistry when regioselectivity is an issue.
