NNN-Pd(II) Pincer Complex Catalyzed Acceptorless Dehydrogenative Coupling and Borrowing Hydrogen Transformations via Metal–Ligand Cooperativity (Nitrene–Imide) in Fluorene Functionalization

Pincer complexes efficiently catalyze reactions to generate
medicinally
important scaffolds using either acceptorless dehydrogenative coupling
(ADC) or borrowing hydrogen process (BHP)-based catalytic reactions.
A few pincer complexes have been reported to catalyze both pathways.
Recently, our group reported the generation of the NNN-Pd(II) pincer
complex and established its catalytic efficiency in ADC and BHP in
two different reactions. The current work discusses the application
of the NNN-Pd(II) catalyst for ADC and BHP on fluorene. Control experiments
and quantum chemical studies were conducted to examine the mechanistic
pathway of the reaction. Utilization of intermediate II-B toward H2 gas elimination or the reduction of alkenylated
fluorene determines the control of selectivity in the formation of
alkylated vs. alkenylated products, depending upon the amount of alcohol
and base.