Electron transfer on cis- and trans-1,2-diphenylcyclopropane: stereoisomerization and formation of 1,3-diphenylpropene and 1,3-diphenylpropane

✍ Scribed by Gernot Boche; Dieter R. Schneider; Klaus Wernicke

• Publisher: Elsevier Science
• Year: 1984
• Tongue: French
• Weight: 259 KB
• Volume: 25
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)81337-x

✦ Synopsis

Reaction of cis-or trans-1,2-diphenylcyclopropane with Na/K leads to stereoisomerization and (after protonation) to 1,3_diphenylpropane and 1,3_diphenylpropene, the latter not being formed by H-migration. Geometrical and structural isomerization of cis-and trans-1,2-diphenylcyclopropane (cis-and trans-5) has been induced by a variety of methods. The thermal reaction between 161 and 220°C ---results in stereoisomerization and no formation of 1,3_diphenylpropene (N'. This reaction provides one of the many examples of thermal stereomutations of cyclopropanes via trimethyle-2 -1

nes . The activation energy of the cis -t tram isomerization amounts to EA = 140.2 kJ mol , la and at equilibrium at 193°C a trans:cis ratio of IO:1 pertains 2C --is a stable 1,3-di-"anion" thus possibly allowing to verify experimentally the prediction of the double lithium bridged structure of the corresponding 1,3_dilithiopropane.

Acknowledgement:

We are grateful to the Fonds der Chemischen Industrie for financial support.

Literature and References