- Cycloisomerization – a straightforward way to benzo[h]quinolines and benzo[c]acridines
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[Figure not available: see fulltext.] Cycloisomerization of 3-alkynyl-2-arylpyridines and quinolines offers a straightforward approach to benzo[h]quinolines and benzo[c]-acridines. Substituent at the triple bond governs a choice between transition metal or Br?nsted acid catalysis. A direct electrophilic activation by trifluoromethanesulfonic acid induces an almost quantitative cyclization of the o-aryl(phenylethynyl) fragment. PtCl2 efficiently catalyzes cyclization of 2-aryl-3-ethynylhetarenes.
- Shestakov, Aleksandr N.,Pankova, Alena S.,Kuznetsov, Mikhail A.
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p. 1103 - 1113
(2017/12/08)
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- Model reactions for the synthesis of azacorannulenes and related heteroaromatic compounds
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4-(2-Ethynylphenyl)pyridine (10), 3-(2-ethynylphenyl)pyridine (11), 2-(2-trimethylsilylethynylphenyl)pyridine (26), and 3-ethynyl-2-phenylpyridine (13) were prepared from readily available pyridine precursors by standard coupling reactions. Pyrolysis of 10 at 810 °C/0.5 Torr provided benzo[f]isoquinoline (45) and the benzopentalene dimer 47. Pyrolysis of 11 (820 °C/0.5 Torr) afforded benzo[f]quinoline (50), benzo[h]i-soquinoline (52), and a mixture of isomers of 47. Pyrolysis of 13 (820 °C/0.3 Torr) provided benzo[h]quinoline (56) and the novel azulene derivative azuleno[1,2-b]pyridine (58). When 26 was desilylated by treatment with TBAF in THF/water, the unusual "dimerization" product 37 was produced; its structure was confirmed by X-ray structural analysis. The mechanisms of these transformations are discussed. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
- Dix, Ina,Doll, Christian,Hopf, Henning,Jones, Peter G.
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p. 2547 - 2556
(2007/10/03)
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