Zn(OAc)₂-mediated Mannich-type reaction was studied for the synthesis of 3,3′-pyrrolidinyl-spirooxindole from l-2,3-dihydro-2-oxotryptophan methyl ester and aldehydes. The study indicates that the Mannich-type spirocyclization is significantly influenced by both the cation and anion of the metal salt, base, stoichiometry, stereoelectronics of aldehyde and temperature. With the enhancement by Zn(OAc)₂, the substrate induced asymmetric reaction works on both aromatic and aliphatic aldehydes but at different temperatures. It could deliver the (2′S,3R,5‘S)-pyrrodinyl-spirooxindole with up to 96% of diastereomeric ratio in good yield under optimized conditions.

研究了Zn（OAc）₂介导的曼尼希型反应，用于由l -2,3-二氢-2-氧色氨酸甲酯和醛类合成3,3'-吡咯烷基-螺氧杂吲哚。研究表明，曼尼希型螺环化反应受金属盐的阳离子和阴离子，碱，化学计量，醛的立体电子学和温度的影响。随着Zn（OAc）₂的增强，底物诱导的不对称反应同时作用于芳族和脂族醛上，但温度不同。在优化的条件下，它可以以良好的产率提供高达96％的非对映异构体比例的（2'S，3R，5'S）-吡咯烷基-螺氧并恶唑。