120346-38-5Relevant articles and documents
Mechanistic Insights into Enantioselective C-H Photooxygenation of Aldehydes via Enamine Catalysis
Walaszek, Dominika J.,Rybicka-Jasińska, Katarzyna,Smoleń, Sabina,Karczewski, Maksymilian,Gryko, Dorota
, p. 2061 - 2070 (2015)
Organocatalytic photooxygenation of 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 depending on a catalyst used. The (S)-enantiomer predominated in imidazolidinone-catalyzed reactions, while prolineamides assured the formation of the (R)-stereoisomer. DFT calculation suggests that the enamine-oxygen complex with the lowest energy has the E,s-cis conformation for the prolineamide derivative and E,s-trans for the imidazolidinone catalyst, explaining the opposite stereoselectivity in the photooxygenation reaction.
