- Thermolysis of Phenyl-substituted 1,2-Dihydronaphthalenes. Evidence for Diphenylbutadienes as Intermediates
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The thermal rearrangement of the four phenyl-substituted 1,2-dihydronaphthalenes (15), (16), (19), and (20) have been studied by flash vacuum pyrolysis (FVP).By using the deuteriated starting compounds -(15) and -(16), it has been established that 1- and 4-phenyl-1,2-dihydronaphthalene (15) and (19) and 2- and 3-phenyl-1,2-dihydronaphthalene (16) and (20) are interconverted via the intermediates 1- and 2-phenyl-2,3-dihydronaphthalene (17) and (18), respectively, through two consecutive, sigmatropic 1,5-hydrogen shifts.In both processes partial oxidation to the corresponding phenylnaphthalenes (21) and (22) takes place.The deuterium distribution in the pyrolysis products suggests that in the hot zone diphenylbutadienes are formed, which are reconverted into phenyldihydronaphthalenes upon reaching the cold receiving flask.By FVP of 4-(p-tolyl)-1,2-dihydronaphthalene (34), 1-phenyl-1-(p-tolyl)butadiene (39), and 1-phenyl-4-(p-tolyl)butadiene (45) the latter type of interconversion could be confirmed.
- Lamberts, Joseph J. M.,Cuppen, Theo J. H. M.,Laarhoven, Wim H.
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p. 1819 - 1828
(2007/10/02)
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- Thermochemistry of Phenyl-Substituted Benzobicyclohex-2-enes
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The thermal rearrangements of benzobicyclohex-2-ene (21) and its phenyl-substituted analogues 22-25 (Scheme V) as models of sterically constrained phenylcyclopropanes have been studied by means of flash vacuum pyrolysis.In most cases the major pathway was cleavage of the "internal" C(1)-C(5) cyclopropane bond followed by a 1,2-hydrogen or a 1,2-phenylshift in the resulting biradical.For 6-phenylbenzobicyclohex-2-ene (25), substantial cleavage of the "external" C(1)-C(6) cyclopropane bond was observed, the phenyl substitution pattern being favorable for stabilization of the resulting biradical 62.Phenyl-substituted 1,2-dihydronaphthalenes 44, 47, 51, and 55 are among the major products.Comparison of the plots of the pyrolysis product composition of the 1,2-dihydronaphthalenes vs. pyrolysis temperature with similar plots of the title compounds (22-25) suggested that some of the minor products, viz., the 1,2-divinylbenzenes 31, 42, and 49, are formed via carbenes 30, 41, 50, 57, and 61 rather than via biradicals.Especially at higher pyrolysis temperatures, a large amount of an oxidation product, viz., 1- or 2-phenylnaphthalene (48 or 54), is formed.
- Lamberts, Joseph J.,Laarhoven, Wim H.
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p. 100 - 106
(2007/10/02)
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- SYNTHESE DU METHOXYCARBONYL-3 INDENE ET DE METHOXYCARBONYL-4 DIHYDRO-1,2 NAPHTALENES. OBTENTION DES β-TETRALONES A PARTIR DES α-TETRALONES CORRESPONDANTES
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The synthesis of variously substituted 3-methoxycarbonylindene and 4-methoxycarbonyl-1,2-dihydronaphthalenes is described.A simple and efficient method for the transformation of 1-tetralone into 2-tetralone is reported.
- Vebrel, Joel,Carrie, Robert
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p. 161 - 166
(2007/10/02)
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