Yoshida Yasushi, Mino Takashi, Sakamoto Masami
Molecular Chirality Research Center, Graduate School of Engineering, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba-shi, Chiba, 263-8522, Japan.
Chemistry. 2017 Sep 18;23(52):12749-12753. doi: 10.1002/chem.201703479. Epub 2017 Aug 29.
The catalytic asymmetric umpolung reaction of ketimines is of great importance, because it can easily provide chiral amines bearing a tetrasubstituted carbon atom on its asymmetric center. Because amino acids with a tetrasubstituted carbon center are useful due to their wide applicability as pharmaceuticals and chiral building blocks, their enantioselective synthesis has great significance in organic synthesis. Herein, we demonstrate a metal-free novel phase-transfer-catalyzed highly regio- and enantioselective umpolung Michael reaction of α-imino esters, which provides amino acid derivatives in high yields with up to 98 % ee. The products are successfully converted into chiral amino acid derivative and δ-lactone with high enantiopurity.
酮亚胺的催化不对称极性反转反应非常重要，因为它能够轻松地提供在不对称中心带有四取代碳原子的手性胺。由于具有四取代碳中心的氨基酸作为药物和手性砌块具有广泛的适用性，因此它们的对映选择性合成在有机合成中具有重要意义。在此，我们展示了一种无金属的新型相转移催化的α-亚氨基酯的高度区域和对映选择性极性反转迈克尔反应，该反应能够以高达98%的对映体过量（ee）高产率提供氨基酸衍生物。产物成功地转化为具有高对映纯度的手性氨基酸衍生物和δ-内酯。
