The application of asymmetric phase‐transfer catalysis to the Strecker reaction of ketimines was realized utilizing bifunctional thiourea‐phosphonium salts. The asymmetric Strecker reaction of aldimines was also realized utilizing quaternaryammoniumsaltsderivedfrom amino acids.
New chiral bifunctional thiourea-phosphonium salts have been developed based on natural amino acids as highly efficient phase-transfer catalysts in the enantioselectiveaza-Henryreaction.
A highly enantioselective1,3-dipolarcycloaddition of imino esters with methyleneindolinones has been realized by using readily available thiourea–quaternary ammonium salts as phase-transfer catalysts, enabling efficient construction of a range of chiral spiro[pyrrolidin-3,3′-oxindoles] in good yields with excellent enantioselectivities under mild conditions.