Advanced Pd–NAPA Precatalysts for Broad‐Scope Kumada–Tamao–Corriu Couplings of Challenging Aryl Chlorides

Abstract A series of NHC and phosphinous acid‐based palladium precatalysts (NAPA), (i.e., 1b – 1d : SIPr‐PdCl 2 ‐PAr 2 (OH)), and their efficiency in catalyzing Kumada–Tamao−Corriu (KTC) couplings are reported. The 1 ‐catalyzed KTC couplings could reach high yields at 50 °C in 3 h. Good results were obtained for strained tetra‐ortho‐substituted biaryl products by raising the temperature to 80 °C and reacting for 3 h. Functional‐group tolerance was achieved using dropwise addition of Grignard reagent during the reaction time course. Upon deprotonation of the ligated PAr 2 (OH), density functional theory (DFT) calculations and negative‐ion mode electrospray mass spectrometer (ESI‐MS) revealed that SIPr tended to dissociate from the Pd(II), implying the succeeding generation of Pd(0)‐P(O − )Ar 2 active species. Compared to Pd(0)‐SPhos and Pd(0)‐NHC, the oxidative addition of 4‐chlorobenzonitrile to Pd(0) was computed, showing the Pd(0)–P(O − )Ar 2 has the lowest activation free energy.