Global Diastereoconvergence in the Ireland–Claisen Rearrangement of Isomeric Enolates: Synthesis of Tetrasubstituted α-Amino Acids
作者:Tyler J. Fulton、Alexander Q. Cusumano、Eric J. Alexy、Yun E. Du、Haiming Zhang、K. N. Houk、Brian M. Stoltz
DOI:10.1021/jacs.0c11480
日期:2020.12.30
A dual experimental/theoretical investigation of the Ireland-Claisen rearrangement of tetrasubstituted α-phthalimido ester enolates to afford α-tetrasubstituted, β-trisubstituted α-amino acids (generally >20:1 dr) is described. For trans allylic olefins, the Z- and E-enol ethers proceed through chair and boat transition states, respectively. For cis allylic olefins, the trend is reversed. As a result
描述了四取代 α-邻苯二甲酰亚胺酯烯醇化物的爱尔兰-克莱森重排以提供 α-四取代、β-三取代 α-氨基酸(通常 >20:1 dr)的双重实验/理论研究。对于反式烯丙基烯烃,Z-和E-烯醇醚分别通过椅子和船过渡态。对于顺式烯丙基烯烃,趋势相反。因此,无论烯醇化物或伴随的烯丙基烯烃的几何形状如何,反应的非对映化学结果都得以保留。我们将所有可能的烯烃异构体的这种独特收敛称为全局非对映收敛。该反应歧管规避了当今α,α-二取代烯丙基酯立体选择性烯醇化技术的局限性。