ISSN:
0009-2940
Keywords:
Bicyclo[1.1.0]butanes, rearrangement
;
Tricyclo[4.1.0.02,7]heptanes, kinetics of thermolysis
;
1,2,3-Methenonaphthalenes, 1,2,3,4-tetrahydro-, kinetics of thermolysis
;
Bicyclo[3.2.0]hept-6-ene derivatives
;
Benzocycloheptene derivatives
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
On the Thermal Rearrangement of the Bicyclo[1.1.0]butane System. A Kinetic Investigation of the Conversion of Tricyclo[4.1.0.02,7]heptanes into Bicyclo[3.2.0]hept-6-enesTricyclo[4.1.0.02,7]heptane (7), its 1- (20) and 2-phenyl derivatives (22), tetracyclo[5.1.0.02,4.03,5]octane (17), 1,2,3,4-tetrahydro-1,2,3-methenonaphthalene (25) as well as its 1- (35), 2- (32), and 3-phenyl derivatives (27) have been thermolyzed in solution in the temperature range between 110 and 230° C. The activation parameters of these reactions have been determined. The parent hydrocarbon 7 is converted into bicyclo[3.2.0]hept-6-ene (11) in high yield, and the other substrates behave analogously, i.e. the cyclobutene derivatives 18, 21, 23, 26, 28, 33, 34, and 36 are formed. Arising from 27, the cyclobutene 28 is observed as intermediate, which is transformed rapidly to a mixture of the benzocycloheptenes 29 and 31. To undergo this ring enlargement, the other cyclobutenes require more severe conditions. The thermal rearrangements of 20, 22, and 27 are accompanied by parallel reactions, which have been identified as acid-catalized processes in the case of 22 and 27 giving rise to the norcarene derivatives 24 and 30, respectively. In 2-phenylmethenonanpthalene 32 two pathways to a cyclobutene derivative exist; they are found to be followed in a 82:18 ratio. The relative reaction rates of all substrates investigated can be interpreted in terms of a consistent mechanistic model. Accordingly, the tricyclo[4.1.0.02,7]heptane system is transformed in a concerted but highly asynchronous process to an (E,Z)-1,3-cycloheptadiene, which then undergoes a rapid conrotatory ring closure to yield the corresponding bicyclo[3.2.0]hept-6-ene.
Additional Material:
4 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19921250229
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