Organocatalyzed Aldol Reaction between Pyridine-2-carbaldehydes and α-Ketoacids: A Straightforward Route towards Indolizidines and Isotetronic Acids
作者:Virginie Liautard、Damien Jardel、Clotilde Davies、Muriel Berlande、Thierry Buffeteau、Dominique Cavagnat、Frédéric Robert、Jean-Marc Vincent、Yannick Landais
DOI:10.1002/chem.201302264
日期:2013.10.18
Enantioselective aldol reactions between substituted pyridine carbaldehydes and α‐ketoacids were shown to provide isotetronic acids or their corresponding pyridinium salts, depending on the nature of the substituents on the pyridine ring. The pyridinium salts were generated through nucleophilic attack of the pyridine nitrogen atom onto the reactive keto functional group. Moderate‐to‐good yields of
根据吡啶环上取代基的性质,取代吡啶甲醛与α-酮酸之间的对映选择性醛醇缩合反应可提供等渗酸或相应的吡啶鎓盐。吡啶鎓盐是通过吡啶氮原子对反应性酮官能团的亲核攻击而生成的。通常使用苯并咪唑吡咯烷I作为催化剂,两种化合物的收率均达到中等至良好水平,并观察到高对映选择性。生成的吡啶鎓盐的氢化导致产生具有高ee的新吲哚并咪唑值和非对映控制。X射线衍射研究可以确定产品的相对构型。最后,进行DFT计算以合理化发散途径与吡啶取代基的关系。