L-脯氨酸/K_2CO_3催化的Claisen-Schmidt反应研究

A Research on L-proline Catalyzed Claisen-Schmidt Reaction

Claisen-Schmidt反应是制备α,β-不饱和酮的重要方法,温和而高选择性的反应是一个有机化学中的难点问题.本文以L-脯氨酸为催化剂,以环己酮和苯甲醛的Claisen-Schmidt缩合反应为模型,对反应条件进行了考察,通过氨基酸、碱及反应溶剂进行了反应筛选和优化.结果表明,L-脯氨酸/K2CO3能高选择性地催化合成α,β-不饱和酮,避免了双缩合产物.在20 mol%的脯氨酸和K2CO3参与下,以DMSO为反应溶剂,反应效果最佳,产率74%.同时,该催化体系下,环己酮与其他芳香醛也高效高选择性地实现缩合反应,产率74~93%.

Claisen-Sehmidt reaction is an important method for the preparation of α,β-unsaturated ketones, in which mild and regioselective synthesis of the mono-condensation product is a difficult problem. This paper, chooses Claisen-Schmidt condensationof cyclohexanone with benzaldehyde as the model reaction, L-proline as catalyst, and investigates a variety of reaction conditions. To optimize reaction results, several amino acids, bases, and solvents are screened, and the results show that L-proline/K2CO3 can successfully catalyze Claisen-Schmidt condensation reaction without bis-condesation. Under 20 tool% of L-proline and with K2CO3 as catalyst in DMSO, the reaction gives corresponding α,β-unsaturated ketone in the best yield of 74%. Under the optimum reaction conditions, the reaction of cyclohexanone with other aromatic aldehydes can be achieved in the yields of 74 - 93%.