Mechanistic Insights into Enantioselective CH Photooxygenation of Aldehydes<i>via</i>Enamine Catalysis
作者:Dominika J. Walaszek、Katarzyna Rybicka-Jasińska、Sabina Smoleń、Maksymilian Karczewski、Dorota Gryko
DOI:10.1002/adsc.201500056
日期:2015.6.15
aldehydes at the α‐position proceeds via enamine catalysis, though enamines should be easily oxidized by singlet oxygen respectively to amides and carbonyl compounds. Moreover, the formation of a zwitterionic enamine peroxide intermediate was postulated based on experimental and theoretical data. The reaction affords desired diols (after in situ reduction) in a decent yield and (S)‐ or (R)‐enantioselectivity
醛在α位的有机催化光氧合反应通过烯胺催化进行,尽管烯胺应容易被单线态氧分别氧化为酰胺和羰基化合物。此外,基于实验和理论数据推测两性离子烯胺过氧化物中间体的形成。根据所用催化剂的不同,该反应可提供合适的收率(原位还原后)和(S)-或(R)-对映选择性的所需二醇。(S)-对映异构体在咪唑烷酮催化的反应中占主导地位,而脯氨酸酰胺确保了(R)立体异构体。DFT计算表明烯胺-氧复合物具有最低能量具有E, š -顺式构象的脯氨酰胺衍生物和E, š -反式的咪唑啉酮的催化剂,说明在光氧化反应的相反立体选择性。