Many thanks to Dr. Peter G. M. Wuts, the world-renowned author and expert in organic synthesis (click here for Wuts Chemical Consulting) for suggesting that we share with the PTC community the excellent review article “Advances in Combined Asymmetric Catalysis of Transition Metal/Phase-Transfer Catalysts” by Yi-Fan Dong, Si-Ru Wang, Zhi-Yong Han, Xiang Wu, Eur. J. Org. Chem. 2025, 28, e202401088.
This review highlights recent advances in the cooperative use of chiral phase-transfer catalysts (PTCs) with transition metal catalysis, an area that has matured significantly over the past two decades. The authors outline how this dual catalytic strategy enables reactivity and stereoselectivity that are often unachievable with either catalyst class alone. Central to this approach is the ability of chiral PTCs, particularly quaternary ammonium and phosphonium salts, to control ion-pairing environments and mediate phase transfer, while transition metals catalyze bond-forming steps. This synergy has proven particularly effective in asymmetric allylic alkylations and related transformations.
The article organizes its discussion around catalyst pairings, with detailed examples involving Pd, Ir, and Ag complexes combined with both cationic and anionic PTCs. Early breakthroughs using cinchona-derived ammonium salts with Pd catalysis established a precedent for enantioselective ion-pair-driven allylations. Further innovations included chiral phosphate-based anionic PTC’s that enabled stereocontrolled arylations and Heck-type reactions, as well as hybrid systems where ion-pairing is integrated directly into ligand design. These diverse systems demonstrate the growing sophistication and versatility of metal/PTC catalysis in complex asymmetric synthesis.
While the majority of current systems rely on precious metals, the authors note the potential for future development using more earth-abundant metals such as nickel and cobalt. Overall, this review serves as a comprehensive resource for understanding the mechanistic logic, structural design, and synthetic potential of combined PTC/transition metal catalysis and underscores the broad utility of this approach in pushing the boundaries of asymmetric methodology.
We highly recommend reading this excellent review article!
