A phase-transfer catalyst (PTC) helps in shifting one reactant from one phase to another phase where the reaction takes place. Starks et al introduced PTC in 1971 for the reaction of an alkyl halide with an inorganic salt in a mixture of water and an organic solvent, without PTC the reaction didn’t take place since the alkyl halide and inorganic salt were separated in different phases. However, a catalytic amount of PTC forms a key intermediate(Q+Nu-) in the interface that can dissolve the alkyl halide and inorganic salt, permitting the interaction to take place and the reaction to proceed. PTC has made significant advances in catalysis and is identified as a versatile methodology in academia and industry bestowed to the use of environment-friendly reagents and water as a solvent, ease of handling the catalysts, mild reaction conditions, and applicability in large-scale processes.2 Besides, asymmetric PTC with chiral structural units has enabled chiral induction possible in reactions and has been of great interest for the past three decades. However, very few effective chiral PTC catalysts have only been reported and used in practical asymmetric transformations. Hence, the design and development of new chiral phase-transfer catalysts remains a fascinating area of investigation in organic synthesis.
The scope of chiral PTC is wide and large including asymmetric alkylation, alkynylation, aromatic nucleophilic substitution, hydroxylation, mannich-type reaction, Michael addition, spirocyclization, desymmetrization, epoxidation, and kinetic resolution. Likewise helpful for sulfenylation, asymmetric biometric transamination, and base-free asymmetric conjugate addition.3,4,5 Our initial aim is to prepare chiral BINOL, bisisoquinoline, based novel chiral PTC for various asymmetric organic transformations.

References:1) Starks, C. M.; Phase-transfer catalysis. I. Heterogeneous reactions involving anion transfer by quaternary ammonium and phosphonium salts J. Am. Chem. Soc. 1971, 93, 195–199. 2) Freedman, H. Industrial Applications of Phase Transfer Catalysis (PTC): Past, Present and Future. Pure Appl. Chem. 1986, 58, 857−868. 3) Hashimoto, T. and Maruoka, K. Recent Development and Application of Chiral Phase-Transfer Catalysts. Chem. Rev. 2007, 107, 5656−5682. 4) Maruoka, K.; Lee, H.J. Recent Asymmetric Phase-Transfer Catalysis with Chiral Binaphthyl-Modified and Related Phase-Transfer Catalysts over the Last 10 Years. The chemical record 2023, e202200286. 5) Penso, M., Albanase, D. New Trends in Asymmetric Phase Transfer Catalysis. Eur. J. Org. Chem. 2023, 26, e202300224.