- Preparation process of L-methyldopa methyl ester
-
The invention relates to a preparation process of L-methyldopa methyl ester and belongs to the field of organic chemical synthesis. The preparation process of the L-methyldopa methyl ester comprises the following steps of 1, sequentially adding L-methyldo
- -
-
Paragraph 0032; 0034; 0035; 0036
(2018/07/15)
-
- Mechanistic Insights into Enantioselective C-H Photooxygenation of Aldehydes via Enamine Catalysis
-
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.
- Walaszek, Dominika J.,Rybicka-Jasińska, Katarzyna,Smoleń, Sabina,Karczewski, Maksymilian,Gryko, Dorota
-
p. 2061 - 2070
(2015/06/23)
-