Stereoselective synthesis of 3,3′-pyrrolidinyl-spirooxindoles via the Zn(OAc)2-mediated asymmetric Mannich-type reaction
作者:Guanping Tang、Samuel K. Akompong、Lianxun Gao、Chen Zeng、Hengjiang Cong、Mian Yang、Long Ye、Yi Liu
DOI:10.1016/j.tetlet.2020.152819
日期:2021.3
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
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。