Asymmetric Morita-Baylis-Hillman Reaction of Conjugated Nitroalkene with Activated Aldehyde Catalyzed by Cinchona Alkaloids / 中国药师

ABSTRACT

Objective:To develop a catalytic system for the asymmetric Morita-Baylis-Hillman ( MBH) reaction of conjugated ni-troalkene with activated aldehyde, and screen out the chiral catalysts with high activity and enantioselectivity. Methods: Totally 21 chiral organocatalysts were applied in the asymmetric MBH reaction ofβ-nitrostyrene with ethyl glyoxylate, and the ee value was deter-mined by chiral HPLC. The effects of temperature, solvent and substrate ratio on the catalytic reaction were investigated. Results: In the presence of cinchona alkaloid catalyst (DHQ)2AQN, β-nitrostyrene reacted with ethyl glyoxylate in toluene at 0℃ affording the MBH adduct in 60% yield with good enantioselectivity (up to 56.9% ee). Conclusion: The bis-cinchona alkaloids with aromatic bridging group are the efficient catalysts for the asymmetric MBH reaction ofβ-nitrostyrene with ethyl glyoxylate, and moderate isolated yield and enantioselectivity are obtained.