金鸡纳生物碱催化的共轭硝基烯与活性醛的不对称Morita-Baylis-Hillman反应

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

目的:创建共轭硝基烯与活性醛的不对称Morita-Baylis-Hillman(MBH)反应催化体系,筛选具有高催化活性及对映选择性的手性催化剂。方法:将21种手性有机小分子催化剂应用于β-硝基苯乙烯与乙醛酸乙酯的不对称MBH反应中,用手性高效液相色谱分析测定产物ee值,并考察温度、溶剂、底物比例等因素对催化反应的影响。结果:在金鸡纳生物碱类催化剂(DHQ)2AQN作用下,β-硝基苯乙烯与乙醛酸乙酯在甲苯中0℃下反应,获得光学纯度为56.9%ee的MBH加成产物,化学产率为60%。结论:以芳香基团作为桥联基的双金鸡纳生物碱类催化剂能够有效地催化β-硝基苯乙烯与乙醛酸乙酯的不对称MBH反应顺利进行,并获得中等程度的化学分离产率及对映选择性。

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 of β-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） 2 AQN, 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 of β-nitrostyrene with ethyl glyoxylate, and moderate isolated yield and enantioselectivity are obtained.