70489-30-4Relevant articles and documents
Sequence-defined oligo(: Ortho -arylene) foldamers derived from the benzannulation of ortho (arylene ethynylene)s
Lehnherr, Dan,Chen, Chen,Pedramrazi, Zahra,Deblase, Catherine R.,Alzola, Joaquin M.,Keresztes, Ivan,Lobkovsky, Emil B.,Crommie, Michael F.,Dichtel, William R.
, p. 6357 - 6364 (2016)
A Cu-catalyzed benzannulation reaction transforms ortho(arylene ethynylene) oligomers into ortho-arylenes. This approach circumvents iterative Suzuki cross-coupling reactions previously used to assemble hindered ortho-arylene backbones. These derivatives form helical folded structures in the solid-state and in solution, as demonstrated by X-ray crystallography and solution-state NMR analysis. DFT calculations of misfolded conformations are correlated with variable-temperature 1H and EXSY NMR to reveal that folding is cooperative and more favorable in halide-substituted naphthalenes. Helical ortho-arylene foldamers with specific aromatic sequences organize functional π-electron systems into arrangements ideal for ambipolar charge transport and show preliminary promise for the surface-mediated synthesis of structurally defined graphene nanoribbons.
Group 4 Diarylmetallocenes as Bespoke Aryne Precursors for Titanium-Catalyzed [2 + 2 + 2] Cycloaddition of Arynes and Alkynes
Reiner, Benjamin R.,Tonks, Ian A.
supporting information, p. 10508 - 10515 (2019/09/13)
Despite the ubiquity of reports describing titanium (Ti)-catalyzed [2 + 2 + 2] cyclotrimerization of alkynes, the incorporation of arynes into this potent manifold has never been reported. The in situ generation of arynes often requires fluoride, which instead will react with the highly fluorophilic Ti center, suppressing productive catalysis. Herein, we describe the use of group 4 diarylmetallocenes, CpR2MAr2 (CpR = C5H5, C5Me5; M = Ti, Zr), as aryne precursors for the Ti-catalyzed synthesis of substituted naphthalenes via coupling with 2 equiv of an alkyne. Fair-to-good yields of the desired naphthalene products could be obtained with 1% catalyst loadings, which is roughly an order of magnitude lower than similar reactions catalyzed by palladium or nickel. Additionally, naphthalenes find broad applications in the electronics, photovoltaics, and pharmaceutical industries, urging the discovery of more economic syntheses. These results indicate that aryne transfer from a CpR2M(?2-aryne) complex to another metal is a viable route for the introduction of aryne fragments into organometallic catalytic processes.
Metal-free benzannulation to synthesis of 2,3-disubstituted naphthalenes: Reaction of 2-(Phenylethynyl)benzaldehyde and alkynes by Br?nsted acid
Umeda, Rui,Ikeda, Naoki,Ikeshita, Masahiro,Sumino, Keita,Nishimura, Sota,Nishiyama, Yutaka
, p. 213 - 215 (2017/08/09)
Metal-free benzannulation reaction of 2-(phenylethynyl)- benzaldehyde and alkynes proceeded in the presence of Br?nsted acid under microwave irradiation to give the 2,3- disubstituted naphthalenes.
Effect of Extended Benzannelation Orientation on Bergman and Related Cyclizations of Isomeric Quinoxalenediynes
Valenzuela, Stephanie A.,Cortés, Alondra J.,Tippins, Zakery J. E.,Daly, Morgan H.,Keel, Terell E.,Gherman, Benjamin F.,Spence, John D.
, p. 13297 - 13312 (2017/12/26)
A combined computational and experimental study was conducted to examine the effect of extended benzannelation orientation on C1-C5 and C1-C6 cyclization of acyclic quinoxalenediynes. Calculations (mPW1PW91/cc-p
A nickel precatalyst for efficient cross-coupling reactions of aryl tosylates with arylboronic acids: Vital role of dppf
Hu, Feng,Lei, Xiangyang
, p. 3854 - 3858 (2014/06/09)
An air-stable and easy-to-handle nickel precatalyst, (9-phenanthrenyl) Ni(II)(PPh3)2Cl, was examined for the cross-coupling reactions of aryl tosylates with arylboronic acids. Under the optimized reaction conditions, the catalytic system tolerates a wide range of activated, neutral and deactivated substrates. The selectivity of this cross-coupling reaction towards aryl tosylates and arylboronic acids has been investigated. It is proposed that ligand 1,1′-bis(diphenylphosphino)ferrocene (dppf) plays a key role in the coupling by enforcing a cis geometry in key intermediates and the active Ni(0) species.
Iron-catalyzed benzannulation reactions of 2-alkylbenzaldehydes and alkynes leading to naphthalene derivatives
Zhu, Shifa,Xiao, Yelin,Guo, Zhengjiang,Jiang, Huanfeng
, p. 898 - 901 (2013/03/28)
An efficient and practical method for the synthesis of naphthalene derivatives via Fe(III)-catalyzed benzannulation of 2-(2-oxoethyl)-benzaldehydes and alkynes has been developed. The system holds the advantages of cheap catalysts, wide substrate scope, and mild reaction conditions.
ZnCl2-catalyzed [4 + 2] benzannulation of 2-ethynylbenzaldehydes with alkynes: Selective synthesis of naphthalene derivatives
Fang, Xiao-Li,Tang, Ri-Yuan,Zhang, Xing-Guo,Zhong, Ping,Deng, Chen-Liang,Li, Jin-Heng
experimental part, p. 352 - 356 (2011/02/16)
Zn-catalyzed [4 + 2] benzannulation of 2-ethynylbenzaldehydes with alkynes is described for the selective synthesis of naphthalene derivatives. In the presence of ZnCl2, a variety of 2-ethynylbenzaldehydes underwent the [4 + 2] benzannulation reactions with alkynes to selectively afford the corresponding naphthalene derivatives in moderate to good yields.
Lewis acid-catalyzed benzannulation via unprecedented [4+2] cycloaddition of o-alkynyl(oxo)benzenes and enynals with alkynes
Asao, Naoki,Nogami, Tsutomu,Lee, Sunyoung,Yamamoto, Yoshinori
, p. 10921 - 10925 (2007/10/03)
The reaction of o-alkynyl(oxo)benzenes 1 with alkynes 2 in the presence of a catalytic amount of AuCl3 in (CH2Cl)2 at 80 °C gave the [4+2] benzannulation products, naphthyl ketone derivatives 3 and 4, in high yields. When the reaction was carried out using AuBr3 instead of AuCl3, the reaction speed was enhanced and the chemical yield was increased. On the other hand, when the reaction was carried out in the presence of a catalytic amount of Cu(OTf)2 and 1 equiv of a Bronsted acid, such as CF2HCO2H, in (CH 2Cl)2 at 100 °C, the decarbonylated naphthalene products 5 were obtained in high yields. Similarly, the Cu(OTf) 2-H2O-promoted reaction of the enynals 7 with an alkyne 2 afforded the corresponding [4+2] benzannulation products, decarbonylated benzene derivatives 8, in good yields. Both AuX3- and Cu(OTf) 2-catalyzed benzannulations proceed most probably through the formation of the benzo[c]pyrylium ate complex 10, the Diels-Alder addition of alkynes 2 to the ate complex, and the resulting bicyclic pyrylium ion intermediate 12. The mechanistic difference between the AuX3 and Cu(OTf)2-HA system is discussed.
Naphthalenes, isoquinolines, and a benzazocine from zirconocene - Copper-mediated coupling of benzocyclobutadiene with nitriles and alkynes
Ramakrishna,Sharp, Paul R.
, p. 877 - 879 (2007/10/03)
(Matrix presented) Commercially available 1-bromobenzocyclobutene is a potentially useful synthon particularly with the application of organometallic methodology. Here we show that it is readily converted into Cp 2Zr(benzocyclobutadiene), which couples with alkynes or nitriles giving five-membered zirconacycles. Treatment of these alkyne- or nitrile-derived zirconacycles with CuCl yields substituted naphthalenes, isoquinolines, or in the presence of MeO2C-CC-CO2Me, a 2-benzazocine containing an eight-membered ring.
Photochemical rearrangement of enediynes: Is a 'photo-Bergman' cyclization a possibility?
Evenzahav, Ariella,Turro, Nicholas J.
, p. 1835 - 1841 (2007/10/03)
The enediynes 1 and 2 were photolyzed in 2-propanol to yield products akin to those analogous to a thermal Bergman cyclization mechanism. In addition, products resulting from photoreduction of one of the triple bonds of the enediyne functionality are also
