- Visible-light-induced oxidation/[3 + 2] cycloaddition/oxidative aromatization to construct benzo[ a]carbazoles from 1,2,3,4-tetrahydronaphthalene and arylhydrazine hydrochlorides
-
An efficient synthesis of benzo[a]carbazoles via visible-light-induced tandem oxidation/[3 + 2] cycloaddition/oxidative aromatization reactions was reported. The benzylic C(sp3)-H of tetrahydronaphthalene was activated through visible-light photoredox catalyst with oxygen as the clean oxidant under mild reaction conditions. This protocol proceeds efficiently with broad substrate scope, and the mechanism study was performed.
- Shen, Jiaxuan,Li, Nannan,Yu, Yanjiang,Ma, Chunhua
-
supporting information
p. 7179 - 7183
(2019/09/30)
-
- Pd-Ni BMNPs Encapsulated in UiO-66 as an Efficient Catalyst for the Activation of “Inert” C?O Bonds
-
A catalytic system based on Pd?Ni bimetallic nanoparticles (BMNPs) encapsulated in the nanocavities of UiO-66 was established for the activation of C?O bonds in ethers. Pd0.25Ni4@UiO-66 catalyst show excellent catalytic performance in the directly methylation and arylation of ethers under a mild reaction condition. High catalytic activity of the catalyst could be ascribed to the “synergistic effect” between the two metal components and strong interaction between BMNPs and the carrier (UiO-66). BMNPs encapsulated in UiO-66 also guarantee a good reusability of the catalyst, the catalyst delivered high catalytic activity for at least four cycles. Our work highlights the great potential value of ethers as powerful alternatives for aryl halides as well as the bright future of BMNPs and MOFs in the catalysis field.
- Zhang, Jia-Wei,Li, Dan-Dan,Lu, Guo-Ping,Deng, Tao,Cai, Chun
-
p. 4258 - 4263
(2018/09/14)
-
- Concerted Catalysis by Adjacent Palladium and Gold in Alloy Nanoparticles for the Versatile and Practical [2+2+2] Cycloaddition of Alkynes
-
A Pd-Au alloy efficiently catalyzed the [2+2+2] cycloaddition of substituted alkynes. Whereas monometallic Pd and Au catalysts were totally ineffective, Pd-Au alloy nanoparticle catalysts with a low Pd/Au molar ratio showed high activity to give the corresponding polysubstituted arenes in high yields. A variety of substituted alkynes participated in various modes of cycloaddition under Pd-Au alloy catalysis. The Pd-Au alloy catalysts exhibited high air tolerance and reusability.
- Miura, Hiroki,Tanaka, Yumi,Nakahara, Karin,Hachiya, Yuka,Endo, Keisuke,Shishido, Tetsuya
-
supporting information
p. 6136 - 6140
(2018/05/03)
-
- Hybrid Catalysis Enabling Room-Temperature Hydrogen Gas Release from N-Heterocycles and Tetrahydronaphthalenes
-
Hybrid catalyst systems to achieve acceptorless dehydrogenation of N-heterocycles and tetrahydronaphthalenes-model substrates for liquid organic hydrogen carriers-were developed. A binary hybrid catalysis comprising an acridinium photoredox catalyst and a Pd metal catalyst was effective for the dehydrogenation of N-heterocycles, whereas a ternary hybrid catalysis comprising an acridinium photoredox catalyst, a Pd metal catalyst, and a thiophosphoric imide organocatalyst achieved dehydrogenation of tetrahydronaphthalenes. These hybrid catalyst systems allowed for 2 molar equiv of H2 gas release from six-membered N-heterocycles and tetrahydronaphthalenes under mild conditions, i.e., visible light irradiation at rt. The combined use of two or three different catalyst types was essential for the catalytic activity.
- Kato, Shota,Saga, Yutaka,Kojima, Masahiro,Fuse, Hiromu,Matsunaga, Shigeki,Fukatsu, Arisa,Kondo, Mio,Masaoka, Shigeyuki,Kanai, Motomu
-
p. 2204 - 2207
(2017/02/23)
-
- Direct C-H bond arylation of arenes with aryltin reagents catalysed by palladium complexes
-
Direct C-H bond arylation of simple arenes with aryltin reagents has been successfully catalysed by PdCl2 in the presence of CuCl2. CuCl2 proved to be an activator for a palladium intermediate as well as an oxidant. The Royal Society of Chemistry.
- Kawai, Hiroshi,Kobayashi, Yasuhiro,Oi, Shuichi,Inoue, Yoshio
-
p. 1464 - 1466
(2008/12/21)
-
- Lewis acid-catalyzed benzannulation via unprecedented [4+2] cycloaddition of o-alkynyl(oxo)benzenes and enynals with alkynes
-
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.
- Asao, Naoki,Nogami, Tsutomu,Lee, Sunyoung,Yamamoto, Yoshinori
-
p. 10921 - 10925
(2007/10/03)
-
- The first cobalt catalyzed [2 + 2 + 2] alkyne cyclotrimerization in aqueous medium at room temperature
-
Chelate complex 1 (5 mol%) was found to catalyze the [2 + 2 + 2] cyclization of terminal alkynes in good yields in a 80/20 mixture of water and ethanol at room temperature without further activation.
- Yong, Li,Butenschoen, Holger
-
p. 2852 - 2853
(2007/10/03)
-
- Reduction of Polycyclic Arenes by BH-Boranes, II Borane Catalyzed Hydrogenation of Naphthalenes to Tetralins
-
Tetrapropyldiborane(6) (TPDB) and triethylborane (TEB) catalyze the regioselective and partial hydrogenation of naphthalene (N) and a number of substituted naphthalenes at 170 deg C to 200 deg C and hydrogen pressures of 25-100 bar.Tetralin (T) is formed quantitatively.Naphthalene derivatives are mainly hydrogenated in the least substituted ring.In the case of alkyl substituents, Lewis acid catalyzed migration and, to a lesser extent C-C bond rupture, lower the yield of the main tetralin derivative.Chlorinated naphthalenes and at the O-atom derivatized naphthols undergo also partial loss of the chloro or oxygen functional groups.The i nitially added borane acts only as a precatalyst and its slowly converted to catalytically active polyboranes of as yet unknown structures.Keywords: Hydroboranes/ Hydrogenation/ Naphthalenes/ Tetralins
- Yalpani, Mohamed,Lunow, Thomas,Koester, Roland
-
p. 687 - 694
(2007/10/02)
-