Phase‐Transfer Catalytic Strategy: Rapid Synthesis of Spiro‐Fused Heterocycles, Integrated with Four Pharmacophores‐Succinimide, Pyrrolidine, Oxindole, and Trifluoromethyl Group
Zhengjun Chen, Liang Wei, Zhuo Chen, Lin Chen
Abstract
Abstract An efficient and practical 1,3‐dipolar [3+2] cycloaddition of N ‐2,2,2‐trifluoroethylisatin ketimines and maleimides has been achieved through phase‐transfer catalytic process by using the cheap quaternary ammonium salt as a catalyst. The strategy grants rapid generation of various complex trifluoromethyl spiro‐fused[succinimide‐pyrrolidine‐oxindole]s in good yields and with excellent diastereoselectivities. The preparative‐scale reaction in conjunction with the optimized Suzuki–Miyaura cross‐coupling derivatizations of the product give prominence to application prospect of this methodology. The investigation on the reaction mechanism implies that the real catalyst in the cycloaddition might be tetrahexylammonium carbonate.