58738-49-1Relevant academic research and scientific papers
A comparative investigation of 1,4-pentamethylene and 1,4-hexamethylene Dewar benzene. Evidence for the intermediate formation of paracyclophane
Straten, J. W. van,Turkenburg, L. A. M.,Wolf, W. H. de,Bickelhaupt, F.
, p. 89 - 97 (2007/10/02)
The synthesis of the title compounds 1a and 1b is described.Starting from the corresponding 1,2-dimethylenecycloalkanes 6, the compounds 1 were obtained in four steps, viz. addition of dichlorocarbene, reduction with triphenyltin hydride, treatemnt with potassium tert-butoxide and silver-ion-catalyzed rearrangement.In the last step, the 1,2-isomers 11 of 1 were also formed, and their thermal rearrangement to the benzocycloalkenes 4 is briefly described.Compound 1b rearranged to its aromatic isomer (6)paracyclophane (2b) both thermally (60 deg C in solution, 100-460 deg C flow pyrolysis) and under silver-ion catalysis at room temperature; in this latter reaction the initially formed 2b was gradually further isomerized to 4b.At higher temperatures, 2b rearranged to the spirotrienes 3b and finally fragmented to give p-ethylstyrene (17).From 1a, the spirotriene 3a and benzocycloheptene (4a) were obtained by thermolysis and by silver-ion catalysis, respectively.The mechanism of these reactions is discussed and it is concluded that (5)paracyclophane (2a) is a transient intermediate in th reaction of 1a.
Electronic and Molecular Structure of Simple 3,3'-Bicyclopropenyls. Photoelectron Spectroscopy and Model Calculations
Spanget-Larsen, Jens,Korswagen, Carla de,Eckert-Maksic, Mirjana,Gleiter, Rolf
, p. 968 - 982 (2007/10/02)
The electronic and molecular structure of 3,3'-bicyclopropenyl (1) and its alkyl derivatives 3,3'-dimethyl-3,3'-bicyclopropenyl (2), dispironona-1,5-diene (3), dispirodeca-1,5-diene (4), dispiroundeca-1,5-diene (5), and dispirododeca-1,5-diene (6) are studied by means of photoelectron spectroscopy and model calculations. 'Through-bond' effects in model compound 1 are analyzed in detail, illustrating a general difficulty with NDO models.Low-energy photoelectron bands of 2-6 can be assigned to ejection of electrons from cyclopropenyl ?- and Walsh-orbitals.Strong 'through-bond' coupling leads to splitting of the ?-bands in the range 1.0-1.5 eV, while the strongly conformation-dependent splitting of the Walsh-bands allows conclusions concerning the preferred torsional angles.The preference of gauche-conformation is predicted for 2 in the gas phase.
