Thermochemistry of Phenyl-Substituted Benzobicyclohex-2-enes

Article abstract of DOI:10.1021/jo00175a020

The thermal rearrangements of benzobicyclo<3.1.0>hex-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-phenylbenzobicyclo<3.1.0>hex-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.

Full text of DOI:10.1021/jo00175a020

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Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.

Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.