239-40-7Relevant academic research and scientific papers
A combined experimental and computational study on the cycloisomerization of 2-ethynylbiaryls catalyzed by dicationic arene ruthenium complexes
Yamamoto, Yoshihiko,Matsui, Kazuma,Shibuya, Masatoshi
supporting information, p. 7245 - 7255 (2015/05/05)
Ruthenium-catalyzed cycloisomerization of 2-ethynylbiaryls was investigated to identify an optimal ruthenium catalyst system. A combination of [η6-(p-cymene)RuCl2(PR3)] and two equivalents of AgPF6 effectively converted 2-ethynylbiphenyls into phenanthrenes in chlorobenzene at 120 °C over 20 h. Moreover, 2-ethynylheterobiaryls were found to be favorable substrates for this ruthenium catalysis, thus achieving the cycloisomerization of previously unused heterocyclic substrates. Moreover, several control experiments and DFT calculations of model complexes were performed to propose a plausible reaction mechanism.
Synthesis of phenanthrenes and polycyclic heteroarenes by transition-metal catalyzed cycloisomerization reactions
Mamane, Victor,Hannen, Peter,Fuerstner, Alois
, p. 4556 - 4575 (2007/10/03)
Readily available biphenyl derivatives containing an alkyne unit at one of their ortho-positions are converted into substituted phenanthrenes on exposure to catalytic amounts of either PtCl2, AuCl, AuCl3, GaCl3 or InCl3 in toluene. This 6-endo-dig cyclization likely proceeds through initial π-complexation of the alkyne unit followed by interception of the resulting η2-metal species by the adjacent arene ring. The reaction is inherently modular, allowing for substantial structural variations and for the incorporation of substituents at any site of the phenanthrene product. Moreover, it is readily extended to the heterocyclic series as exemplified by the preparation of benzoindoles, benzocarbazoles, naphthothiophenes, as well as bridgehead nitrogen heterocycles such as pyrrolo[1,2-a]quinolines. Depending on the chosen catalyst, biaryls bearing halo-alkyne units can either be converted into the corresponding 10-halo-phenanthrenes or into the isomeric 9-halo-phenanthrenes; in the latter case, the concomitant 1,2-halide shift is best explained by assuming a metal vinylidene species as the reactive intermediate. The scope of this novel method for the preparation of polycyclic arenes is illustrated by the total synthesis of a series of polyoxygenated phenanthrenes that are close relatives of the anticancer agent combretastatin A-4, as well as by the total synthesis of the aporphine alkaloid O-methyl-dehydroisopiline and its naturally occurring symmetrical dimer.
Indolopyridines containing a bridgehead heteroatom 12. Synthesis and reduction of 12-arylidene-5,6-dihydroindolo[2,1-a]isoquinolinium trifluoroacetates
Soldatenkov,Soldatova,Ryashentseva,Ntaganda,Zvolinskii,Smirnova,Kharlamova
, p. 2116 - 2120 (2007/10/03)
Condensation of 5,6-dihydroindolo[2,1-a]isoquinoline with aromatic aldehydes in trifluoroacetic acid afforded 12-arylidene-5,6-dihydroindolo[2,1-a]isoquinolinium trifluoroacetates. Hydrogenolysis of these salts on rhenium heptasulfide at elevated temperature and hydrogen pressure yielded indolo [2,1-a]isoquinolines, while reduction with sodium borohydride gave 12-arylmethylindoloisoquinolines. Photoluminescence was found for some indolo[2,1-a]isoquinolines.
INDOLOPYRIDINES WITH A HETERO ATOM AT A POSITION OF FUSION. 5. CATALYTIC SYNTHESIS OF INDOLOISOQUINOLINE BY PYROLYSIS OF BENZYLISOQUINOLINES
Soldatova, S.A.,Alarcon, J. A. Rodriguez,Soldatenkov, A. T.
, p. 69 - 72 (2007/10/02)
High-temperature heterocyclization of α-benzylisoquinolines on oxide-type catalysts gave angular indoloisoquinoline.
