A dual catalytic system has been developed following the screening of a series of chiral primary amine catalysts and chiral phosphoric acid catalysts for the Michael addition of cyclic ketones to nitroolefins bearing only one a-substituent. The resulting g-nitro ketones, which contain a substituent on the carbon connected to the nitro group, were formed in excellent yields (> 80%) with high levels of stereoselectivity (up to 94:6 dr and 98% ee) when the reaction was performed in benzene at 0 8C with 10 mol% of the optimal amine/phosphoric acid combination (1:1) as a catalyst. Subsequent reduction of the nitro group followed by intramolecular reductive amination could afford optically active cis-octahydroindole analogues bearing a non-functional substituent at their 2-position.
A series of α-substituted nitroolefins were employed in organocatalytic asymmetric Michael reactions with aldehydes. γ-Nitro carbonyl products were achieved in good yields (up to 86%) with good stereoselectivities (up to 96% ee and 24 : 1 dr). Reduction of the nitro group followed by intramolecular reductive amination successfully afforded various novel optically active 2,4-disubstituted pyrrolidine compounds.
Novel fulgides, 5-selenazolyl fulgides, were synthesized and E and Z isomers were directly separated by column chromatography. E ↔ Z photo-isomerization was only observed during conventional UV light irradiation. Using the pulse laser-photolysis method, photochromic processes were studied. Both the excited singlet state and excited triplet state contribute to photo-cyclization reaction to form the colored form (closed form). The closed form is unstable and quickly goes back to the open form. Solvent has remarkable effect on absorption spectra of the closed form.
A dual catalytic system is developed following the screening of a series of chiral primary amine catalysts and chiral phosphoric acid catalysts for the Michael addition of cyclic ketones to nitro olefins bearing only one α‐substituent.
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