Thermal transformations of cis-1,2-dibenzoylalkenes

Journal Article · Fri Aug 01 04:00:00 EDT 1980 · J. Org. Chem.; (United States)

DOI:https://doi.org/10.1021/jo01304a009· OSTI ID:5030410

Chipman, D M ^[1]; Chauhan, S M.S.; George, M V

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1. Univ. of Notre Dame, IN

Thermal transformations of a few cis-1,2-dibenzoylalkenes such as 2,3-dibenzoylbicyclo(2.2.2)oct-2-ene (12), 2,3-dibenzoyl-7-oxabicyclo(2.2.1)hept-2-ene (16), and 2,3-dibenzoylbicyclo(2.2.1)hept-2-ene (19) have been examined. Thermolysis of 12 gave 2-benzoyl-3-phenylbicyclo(2.2.2)oct-2-ene (14) through the loss of CO from the lactone precursor 13. The thermolysis of 16, on the other hand, gave 3,4-dibenzoylfuran (17), through a fragmentation reaction. In contrast, the thermolysis of 19 gave 2-endo-3-exo-dibenzoylbicyclo(2.2.1)heptane (20), probably through a disproportionation reaction. Ab initio molecular orbital calculations were made on model compounds representing the conversion of cis-1,2-dibenzoylalkenes to the corresponding lactones to determine whether mechanisms involving intermediates such as the bicyclic structure 23, the dipolar structure 25, and the diradical structure 28 (Scheme IV) are feasible under thermal conditions. The bicyclic structure 23 is found to be easily accessible, lying between the starting material and final product in energy. Any mechanism involving the dipolar intermediate 25 seems to be less likely. The intermediate 28, which is geometrically similar to 25 but is of diradical rather than dipolar nature, is found to be comparable in energy to the starting material. It is concluded that the actual mechanism may then involve 23, 28, or perhaps even both of these.

• OSTI ID: 5030410
• Journal Information: J. Org. Chem.; (United States), Journal Name: J. Org. Chem.; (United States) Vol. 45:16; ISSN JOCEA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ALKENES
AROMATICS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DECOMPOSITION
ESTERS
HETEROCYCLIC COMPOUNDS
HIGH TEMPERATURE
HYDROCARBONS
KINETICS
LACTONES
MOLECULAR ORBITAL METHOD
MOLECULAR STRUCTURE
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PYROLYSIS
REACTION KINETICS
THERMOCHEMICAL PROCESSES