Phase transfer catalyzed tert-alkylations of cyclopentadiene and indene: indications for set processes

Abstract

Scope and mechanism of the PTC tert-alkylation of cyclopentadienide anion have been investigated. On the side of the anion, the reaction is limited to cyclopentadiene and indene, whereas many tertiary as well as secondary and primary alkylating agents can be employed. Hexamethylcyclopentadiene 8, for instance, is available easily. Tert-alkylations of this type are more effective if 4,4′-bipyridinium salts are present in addition to a phase transfer catalyst. The reactions involve probably an initial single electron transfer (SET) step.