Isomerization of dihydroazulenes to substituted azulenes - naked eye observation of a novel Cope-type rearrangement.
作者:Klaus Hafner、Jens Hartung、Claudia Syren
DOI:10.1016/s0040-4020(01)81580-5
日期:1992.6
Readily accessible 3a-bridgehead allylic or propargylic substituted dihydroazulenes 9 rearrange at roomtemperature to thermodynamic more stable substituted azulenes. This process is parallel by a gradual change in color: the yellow solution of the starting pentaenes e.g. 9a smoothly turns to green and finally to the brilliant blue of 10a at the end of the reaction. Activation parameters for one example