1055-26-1Relevant academic research and scientific papers
Palladium-Catalyzed [3 + 2] Annulation of Alkynes with Concomitant Aromatic Ring Expansion: A Concise Approach to (Pseudo)azulenes
Zhou, Fulin,Shi, Weiming,Liao, Xingrong,Yang, Yudong,Yu, Zhi-Xiang,You, Jingsong
, p. 676 - 686 (2022/01/15)
The construction of (pseudo)azulenes represents an appealing yet challenging task in organic synthetic chemistry. Herein, we disclose a palladium-catalyzed [3 + 2] annulation technique of alkynes with concomitant aromatic ring expansion driven by a diboron reagent and iodide, affording a concise approach to azulenes (7-fused-5 bicycle) and pseudoazulenes (6-fused-5 bicycle). Compared with the documented synthetic strategies, the route to (pseudo)azulenes developed herein is applicable for both homo- and cross-annulation processes and exhibits a broad substrate scope. It is worth noting that this transformation is not only suitable for the ring expansion of the phenyl moiety to afford azulenes but also applicable to the ring expansion of the electron-rich five-membered heterocycles to deliver pseudoazulenes. Experimental and computational investigations on the mechanism support the formal trans-palladium-boration across the alkyne, cis-addition of the alkyne, dearomative spiroannulation, and aromatic ring expansion process.
ACYLATION OF ACETYLENES BY ACETYL FLUOROSULFONATE. AN UNUSUAL REACTON OF DIPHENYLACETYLENE WITH ACETYL FLUOROSULFONATE
Gavrishova, T. N.,Shastin, A. V.,Balenkova, E. S.
, p. 1064 - 1067 (2007/10/02)
The reaction of cyclopropylacetylene, phenylacetylene, and 1-hexyne with acetyl fluorosulfonate, generated in situ from acetyl fluoride and sulfur trioxide, with methanol and acetonitrille as external nucleophiles takes place regio- and stereospecificaly
The reaction of (η5-cyclopentadienyl)dicarbonyliron(2-thienoyl) with acetylenes; a mechanistic study using proton nuclear magnetic resonance, and application in synthesis
Butler, Ian R.
, p. 1979 - 1987 (2007/10/02)
The thermal reaction of dicarbonyl-η5-cyclopentadienyl(2-thienoyl)iron with a series of substituted acetylenes to give indenones and cyclopentathiophenones have been reinvestigated.The results obtained support a reaction mechanism involving initial acetylene insertion followed by that of carbon monoxide, in contradiction to the previously reported results.The reaction products were identified and characterized primarily using 2D 1H nmr spectroscopy.
Reactivity of Titanium(II) Arene Derivatives with Substituted Alkynes. Cyclooligomerization Reactions and Crystal and Molecular Structure of 4-C4(C6H5)4>Ti2
Calderazzo, Fausto,Marchetti, Fabio,Pampaloni, Guido,Hiller, Wolfgang,Antropiusova, Helena,Mach, Karel
, p. 2229 - 2238 (2007/10/02)
By treating Ti(η6-toluene)2 (X = Cl: 1a, X = Br: 1b) with C2R2 (R = Me, Ph) tetraorganylcyclobutadiene complexes of formula Ti(η4-C4R4)2 (R = Ph, X = Cl: 2a, X = Br: 2b; R = Me, X = Br: 3b) have been obtained in good yields.Compound 2b has been studied by X-ray diffraction methods.The titanium atom possesses an approximate square pyramidal coordination, the apical position being occupied by the symmetrically bonded tetraphenylcyclobutadiene ring, the four bridging bromides to the two AlBr2 groups forming the base of the pyramid, 0.99 Angstroem away from the titanium atom.The tetrabromoaluminato moiety of 2b can be substituted by carbocyclic anionic ligands, such as Cp and COT, and the corresponding complexes 4 and Ti(4h4-C4Ph4)(COT) were obtained.The spectroscopic study of the Ti(η6-benzene)2/diphenylacetylene (DPA) system (X = Cl: 5a, X = Br: 5b) has revealed the existence of three products, corresponding to the 1:1, 1:2, and 1:3 molar ratios.The possible role of the known AlX3 * C4R4 complexes in this reaction is discussed.The cyclotrimerization reactions of substituted acetylenes in the presence of η6-arene titanium(II) complexes as precursors have been studied.In toluene or methylcyclohexane Ti(η6-toluene)2 was found to catalyze the formation of alkyl-substituted aromatic hydrocarbons from 2-butyne, phenylacetylene, and 1-hexyne at about 80 deg C over 15 h with turnovers (moles of converted alkyne per mole titanium) of about 520, 900, and 990, respectively.The cyclooligomerization of DPA in the presence of Ti(η6-benzene)>(μ-X)2(AlX2)>2 (X = Cl, Br) was studied in detail.The activity of the chloro derivative 5a is higher than that of the bromide catalytic precursor 5b.In addition to hexaphenylbenzene and octaphenylcyclooctatetraene, other oligomerization by-products (triphenylethylene, 1,1,2,2-tetraphenylethane, 1,2,3-triphenylnaphthalene, and 1,2,3-triphenylazulene) were observed, whose formation was drastically reduced in the presence of alkyl aluminium halides. - Key Words: Titanium / Cyclooligomerization / Acetylenes, substituted / Tetraphenylcyclobutadiene, ligand
GENERATION OF AZULENE RADICAL CATION FROM ARYLALKYNES
Cooksey, Christopher J.,Courtneidge, John L.,Davies, Alwyn G.,Gregory, Peter S.,Evans, Jeffrey C.,Rowlands, Christopher C.
, p. 807 - 814 (2007/10/02)
If a diarylalkyne 4-XC6H4CCR (R=Ph, 4-MeC6H4, or 4-ButC6H4) or 1-phenylpropyne in trifluoroacatic acid containing mercury(II) trifluoroacetate is irradiated with u.v. light filtered through Pyrex glass, the e.s.r. spectrum of the corresponding azulene can be obsreved.The azulenes have been isolated and converted back into their radical cations by irradiation in trifluoroacetic acid, or in dichloromethane containing (4-BrC6H4)3N+. or (2,4-Br2C6H3)3N+..Possible mechanisms by which the azulenes are formed the alkynes are discussed.
The Generation of Azulene Radical Cations from Arylalkynes
Cooksey, Christopher J.,Courtneidge, John L.,Davies, Alwyn G.,Evans, Jeffrey C.,Gregory, Peter S.,Rowlands, Christopher C.
, p. 549 - 550 (2007/10/02)
Arylalkynes ArCCR (R = alkyl or aryl) undergo one-electron oxidation with dimerization and rearrangement to show the e.s.r. spectra of the corresponding azulene radical cations.
Benzothiophene S-Oxides and Related Compounds from the Reactions of Arylalkynes and Antimony Pentafluoride in Sulfur Dioxide
Fan, Ru-Lin,Dickstein, Jerome I.,Miller, Sidney I.
, p. 2466 - 2469 (2007/10/02)
When treated with antimony pentafluoride and benzene in liquid sulfur dioxide, certain alkynes yield 2-X-3-phenylbenzothiophene S-oxides (X = Ph, Cl, Br) or 1,1-diphenyl-2-X-vinylsulfinic acids (X = H, Br).Though limited, this is a facile route to both types of compounds.
