Catalytic Conjugate Additions of Carbonyl Anions under Neutral Aqueous Conditions
作者:Michael C. Myers、Ashwin R. Bharadwaj、Benjamin C. Milgram、Karl A. Scheidt
DOI:10.1021/ja0520161
日期:2005.10.1
The conjugate addition of carbonyl anions catalyzed by thiazolium salts that is fully operative under neutral aqueous conditions has been accomplished. The combination of alpha-keto carboxylates and thiazolium-derived zwitterions produces reactive carbonyl anions in a buffered protic environment that readily undergo conjugate additions to substituted alpha,beta-unsaturated 2-acyl imidazoles. The scope
由噻唑鎓盐催化的羰基阴离子的共轭加成在中性水性条件下完全有效。α-酮羧酸盐和噻唑鎓衍生的两性离子的组合在缓冲质子环境中产生反应性羰基阴离子,这些阴离子很容易与取代的 α,β-不饱和 2-酰基咪唑发生共轭加成。已经检查了反应的范围,发现可以适应各种 α-酮羧酸盐和 β-芳基取代的不饱和 2-酰基咪唑。该过程的最佳预催化剂是市售的噻唑鎓盐 5,一种硫胺二磷酸的简单类似物。在这个过程中,没有观察到来自羰基阴离子二聚反应的安息香产物。对应的 1,