Bis(enamino-Cp) Group 4 metal complex chemistry: developing a Mannich-type carbon-carbon coupling reaction at the bent metallocene famework

Deprotonation of 6-methyl-6-dialkylaminofulvenes (2) yield the enamino-substituted cyclopentadienide reagents (3). Their treatment with, e.g., zirconium tetrachloride generates the bis(dialkylaminoethenyl)zirconocene dichloride complexes that subsequently undergo a facile acid-catalyzed intramolecular Mannich-type carbon-carbon coupling reaction to yield the unsaturated aminobutadien-1,3-diyl-bridged ansa-metallocenes.