C-Selective and Diastereoselective Alkyl Addition to β,γ-Alkynyl-α-imino Esters with Zinc(II)ate Complexes
作者:Manabu Hatano、Kenji Yamashita、Mai Mizuno、Orie Ito、Kazuaki Ishihara
DOI:10.1002/anie.201408916
日期:2015.2.23
Since umpolung α‐imino esters contain three electrophilic centers, regioselective alkyl addition with traditional organometallic reagents has been a serious problem in the practical synthesis of versatile chiral α‐amino acid derivatives. An unusual C‐alkyl addition to α‐imino esters using a Grignard reagent (RMgX)‐derived zinc(II)ate was developed. Zinc(II)ate complexes consist of a Lewis acidic [MgX]+
由于蛋白酚α-亚氨基酯包含三个亲电中心,因此在传统合成通用手性α-氨基酸衍生物中,传统有机金属试剂的区域选择性烷基加成一直是一个严重的问题。开发了使用格利雅试剂(RMgX)衍生的锌(II)盐向α-亚氨基酯中添加不寻常的C烷基的方法。锌(II)酸盐配合物由路易斯酸性[MgX] +部分,亲核性[R 3 Zn] -部分和2 [MgX 2 ]组成。因此,离子分离的[R 3 Zn] -选择性地攻击亚氨基碳原子,该亚氨基碳原子最容易被[MgX] +的螯合活化。特别是,由于结构方面的考虑,手性β,γ-炔基-α-亚氨基酯可以强烈促进高度区域和非对映选择性的C-烷基化,并在5分钟内以高至产量。