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.