手性硫脲-酰胺催化1,3-二酮对硝基烯烃的不对称Michael加成反应

Asymmetric Conjugate Addition of 1,3-Diketone to Nitroalkenes Catalyzed by Bifunctional Thiourea-Amide Organocatalysts

合成了一系列新型硫脲-酰胺有机小分子催化剂,将该类催化剂应用于2,4-戊二酮对各种取代硝基烯烃的不对称Michael加成反应中,在1mol%催化剂用量情况下,以较高的产率和优异的对映选择性(最高94%ee)得到了加成产物.该催化体系具有广泛的适应性,能够适合含有吸电子和供电子基团的各种硝基烯烃的不对称加成.初步的构效关系研究表明,吡咯烷N-酰基结构单元在催化反应中起到重要作用.

New bifunctional chiral thiourea-amide organocatalysts were developed.Their applications in asymmetric conjugate addition of 2,4-pentandione to various nitroalkenes were investigated.The corresponding adducts were obtained in excellent yields with high enantioselectivities up to 94%ee in present of 1 mol%catalyst.The catalytic system could also suit for various nitroalkenes bearing electron-donating or electron-withdrawing groups.The preliminary structure-activity relationship study reveals that the acyl group in pyrrolidine N position plays an important role in catalyzing the reaction.