Probing α‐Amino Aldehydes as Weakly Acidic Pronucleophiles: Direct Access to Quaternary α‐Amino Aldehydes by an Enantioselective Michael Addition Catalyzed by Brønsted Bases
作者:Ane García‐Urricelqui、Abel Cózar、Antonia Mielgo、Claudio Palomo
DOI:10.1002/chem.202004468
日期:2021.2
The high tendency of α‐amino aldehydes to undergo 1,2‐additions and their relatively low stability under basic conditions have largely prevented their use as pronucleophiles in the realm of asymmetric catalysis, particularly for the production of quaternary α‐amino aldehydes. Herein, it is demonstrated that the chemistry of α‐amino aldehydes may be expanded beyond these limits by documenting the first
α-氨基醛很容易发生1,2-加成反应,并且在碱性条件下具有相对较低的稳定性,这在很大程度上阻止了它们在不对称催化领域用作亲核试剂,特别是在生产季α-氨基醛方面。本文证明了α-氨基醛的化学性质可能超出了这些限制,方法是记录α-支链α-氨基醛与硝基烯烃的首次直接α-烷基化反应。该反应产生具有多达非对映和对映选择性的稠密的官能化产物,该产物带有多达两个的四级和三级邻位立体中心。DFT建模提出了这样的建议,即在NH基团与起始α-氨基醛中的羰基氧原子之间的分子内氢键是反应立体控制的关键。