... Therefore, the asymmetric synthesis of N,S-acetals is a challenging project for the addition of thiols to imines catalyzed by phase-transfer catalysts. ... entry, 1, R 1, 2, R 2, 3, ee (%) b. 1, 1a, Ph, 2a, p-ClC 6 H 4, 3a, 90. ... 10, 1e, p-NO 2 C 6 H 4, 2a, p-ClC 6 H 4, 3j, 47. ...