A [2+2+2]-Cyclotrimerization Approach to Selectively Substituted Fluorenes and Fluorenols, and Their Conversion to 9,9-Spirobifluorenes
2015
Abstract
Synthesis of selectively substituted fluorenes and fluorenols was achieved by using catalytic [2+2+2]cyclotrimerization. Various starting diynes were reacted with different alkynes in the presence of a catalytic amount of Wilkinson's catalyst (RhCl(PPh3)(3)) providing the compounds possessing the fluorene scaffold in good isolated yields.
A set of four regioselectively substituted fluorenols was converted to the corresponding 9,9-spirobifluorenes and their spectral characteristics were measured.