Kondoh Azusa, Oishi Masafumi, Tezuka Hikaru, Terada Masahiro
Research and Analytical Center for Giant Molecules, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai, 980-8578, Japan.
Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai, 980-8578, Japan.
Angew Chem Int Ed Engl. 2020 May 4;59(19):7472-7477. doi: 10.1002/anie.202001419. Epub 2020 Mar 6.
In the field of chiral Brønsted base catalysis, a new generation of chiral catalysts has been highly anticipated to overcome the intrinsic limitation of pronucleophiles that are applicable to the enantioselective reactions. Herein, we reveal conceptually new chiral Brønsted base catalysts consisting of two different organobase functionalities, one of which functions as an organosuperbase and the other as the substrate recognition site. Their prominent activity, which stems from the distinctive cooperative function by the two organobases in a single catalyst molecule, was demonstrated in the unprecedented enantioselective direct Mannich-type reaction of α-phenylthioacetate as a less acidic pronucleophile. The present achievement would provide a new guiding principle for the design and development of chiral Brønsted base catalysts and significantly broaden the utility of Brønsted base catalysis in asymmetric organic synthesis.
在手性布朗斯特碱催化领域，人们一直高度期待新一代手性催化剂，以克服适用于对映选择性反应的亲核前体的内在局限性。在此，我们揭示了一种概念上全新的手性布朗斯特碱催化剂，它由两种不同的有机碱官能团组成，其中一个起有机超强碱的作用，另一个作为底物识别位点。在α-苯硫基乙酸酯作为酸性较弱的亲核前体的前所未有的对映选择性直接曼尼希型反应中，证明了它们突出的活性，这源于单个催化剂分子中两种有机碱独特的协同作用。本研究成果将为手性布朗斯特碱催化剂的设计和开发提供新的指导原则，并显著拓宽布朗斯特碱催化在不对称有机合成中的应用范围。
